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-rw-r--r--tools/depotfmt.nix3
-rw-r--r--tvix/eval/.skip-subtree2
-rw-r--r--tvix/eval/src/eval.rs9
-rw-r--r--tvix/eval/src/main.rs7
-rw-r--r--tvix/eval/src/tests/mod.rs28
-rw-r--r--tvix/eval/src/tests/nix_tests/README.md8
-rw-r--r--tvix/eval/src/tests/nix_tests/binary-databin0 -> 1024 bytes
-rw-r--r--tvix/eval/src/tests/nix_tests/data1
-rw-r--r--tvix/eval/src/tests/nix_tests/dir1/a.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/dir2/a.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/dir2/b.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/dir3/a.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/dir3/b.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/dir3/c.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/dir4/a.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/dir4/c.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-fail-abort.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-fail-antiquoted-path.nix4
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-fail-assert.nix5
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-fail-bad-antiquote-1.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-fail-bad-antiquote-2.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-fail-bad-antiquote-3.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-fail-blackhole.nix5
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-fail-deepseq.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-fail-hashfile-missing.nix5
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-fail-missing-arg.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-fail-path-slash.nix6
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-fail-remove.nix5
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-fail-scope-5.nix10
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-fail-seq.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-fail-substring.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-fail-to-path.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-fail-undeclared-arg.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-any-all.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-any-all.nix11
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-arithmetic.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-arithmetic.nix59
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-attrnames.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-attrnames.nix11
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-attrs.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-attrs.nix5
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-attrs2.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-attrs2.nix10
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-attrs3.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-attrs3.nix22
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-attrs4.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-attrs4.nix7
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-attrs5.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-attrs5.nix21
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-attrs6.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-attrs6.nix4
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-autoargs.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-autoargs.flags1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-autoargs.nix15
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-backslash-newline-1.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-backslash-newline-1.nix2
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-backslash-newline-2.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-backslash-newline-2.nix2
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-builtins-add.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-builtins-add.nix8
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-builtins.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-builtins.nix12
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-callable-attrs.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-callable-attrs.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-catattrs.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-catattrs.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-closure.exp.xml343
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-closure.nix13
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-comments.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-comments.nix59
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-concat.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-concat.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-concatmap.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-concatmap.nix5
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-concatstringssep.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-concatstringssep.nix8
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-context-introspection.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-context-introspection.nix24
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-context.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-context.nix6
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-curpos.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-curpos.nix5
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-deepseq.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-deepseq.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-delayed-with-inherit.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-delayed-with-inherit.nix24
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-delayed-with.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-delayed-with.nix29
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs-2.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs-2.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs-bare.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs-bare.nix17
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs.nix17
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-elem.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-elem.nix6
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-empty-args.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-empty-args.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-eq-derivations.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-eq-derivations.nix10
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-eq.exp.disabled1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-eq.nix3
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-filter.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-filter.nix5
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-flatten.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-flatten.nix8
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-float.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-float.nix6
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-fromTOML.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-fromTOML.nix208
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-fromjson-escapes.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-fromjson-escapes.nix3
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-fromjson.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-fromjson.nix36
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-functionargs.exp.xml15
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-functionargs.nix80
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-getattrpos-undefined.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-getattrpos-undefined.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-getattrpos.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-getattrpos.nix6
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-getenv.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-getenv.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-hash.exp0
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-hashfile.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-hashfile.nix4
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-hashstring.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-hashstring.nix4
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-if.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-if.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-import.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-import.nix11
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-ind-string.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-ind-string.nix128
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-let.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-let.nix5
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-list.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-list.nix7
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-listtoattrs.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-listtoattrs.nix11
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-logic.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-logic.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-map.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-map.nix3
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-mapattrs.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-mapattrs.nix3
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-nested-with.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-nested-with.nix3
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-new-let.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-new-let.nix14
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-null-dynamic-attrs.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-null-dynamic-attrs.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-overrides.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-overrides.nix9
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-partition.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-partition.nix5
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-path.nix7
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-pathexists.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-pathexists.nix5
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-patterns.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-patterns.nix16
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-readDir.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-readDir.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-readfile.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-readfile.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-redefine-builtin.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-redefine-builtin.nix3
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-regex-match.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-regex-match.nix29
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-regex-split.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-regex-split.nix48
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-remove.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-remove.nix5
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-replacestrings.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-replacestrings.nix11
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-scope-1.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-scope-1.nix6
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-scope-2.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-scope-2.nix6
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-scope-3.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-scope-3.nix6
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-scope-4.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-scope-4.nix10
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-scope-6.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-scope-6.nix7
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-scope-7.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-scope-7.nix6
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-search-path.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-search-path.flags1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-search-path.nix11
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-seq.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-seq.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-sort.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-sort.nix8
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-splitversion.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-splitversion.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-string.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-string.nix12
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-strings-as-attrs-names.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-strings-as-attrs-names.nix20
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-substring.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-substring.nix21
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-tail-call-1.exp-disabled1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-tail-call-1.nix3
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-tojson.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-tojson.nix13
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-toxml.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-toxml.nix3
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-toxml2.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-toxml2.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-tryeval.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-tryeval.nix5
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-types.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-types.nix37
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-versions.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-versions.nix40
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-with.exp1
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-with.nix19
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-xml.exp.xml52
-rw-r--r--tvix/eval/src/tests/nix_tests/eval-okay-xml.nix21
-rw-r--r--tvix/eval/src/tests/nix_tests/imported.nix3
-rw-r--r--tvix/eval/src/tests/nix_tests/imported2.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/lib.nix61
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-fail-dup-attrs-1.nix4
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-fail-dup-attrs-2.nix13
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-fail-dup-attrs-3.nix13
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-fail-dup-attrs-4.nix4
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-fail-dup-attrs-7.nix9
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-fail-dup-formals.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-fail-mixed-nested-attrs1.nix4
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-fail-mixed-nested-attrs2.nix4
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-fail-patterns-1.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-fail-regression-20060610.nix11
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-fail-uft8.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-fail-undef-var-2.nix7
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-fail-undef-var.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-okay-1.nix1
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-okay-crlf.nix17
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-okay-dup-attrs-5.nix4
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-okay-dup-attrs-6.nix4
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-okay-mixed-nested-attrs-1.nix4
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-okay-mixed-nested-attrs-2.nix4
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-okay-mixed-nested-attrs-3.nix7
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-okay-regression-20041027.nix11
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-okay-regression-751.nix2
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-okay-subversion.nix43
-rw-r--r--tvix/eval/src/tests/nix_tests/parse-okay-url.nix7
-rw-r--r--tvix/eval/src/tests/nix_tests/readDir/bar0
-rw-r--r--tvix/eval/src/tests/nix_tests/readDir/foo/git-hates-directories0
248 files changed, 2217 insertions, 9 deletions
diff --git a/tools/depotfmt.nix b/tools/depotfmt.nix
index dbd3a31a0d..400f4ed5fd 100644
--- a/tools/depotfmt.nix
+++ b/tools/depotfmt.nix
@@ -23,8 +23,7 @@ let
     command = "${pkgs.nixpkgs-fmt}/bin/nixpkgs-fmt"
     includes = [ "*.nix" ]
     excludes = [
-      "third_party/nix/tests/*",
-      "third_party/nix/src/tests/*"
+      "tvix/eval/src/tests/*",
     ]
 
     [formatter.rust]
diff --git a/tvix/eval/.skip-subtree b/tvix/eval/.skip-subtree
new file mode 100644
index 0000000000..05f9fc116f
--- /dev/null
+++ b/tvix/eval/.skip-subtree
@@ -0,0 +1,2 @@
+Do not traverse further, readTree will encounter Nix language tests
+and such and fail.
diff --git a/tvix/eval/src/eval.rs b/tvix/eval/src/eval.rs
index 370aad494d..5e6c53cd8b 100644
--- a/tvix/eval/src/eval.rs
+++ b/tvix/eval/src/eval.rs
@@ -1,9 +1,9 @@
 use rnix::{self, types::TypedNode};
 
-use crate::errors::EvalResult;
+use crate::{errors::EvalResult, value::Value};
 
-pub fn interpret(code: String) -> EvalResult<String> {
-    let ast = rnix::parse(&code);
+pub fn interpret(code: &str) -> EvalResult<Value> {
+    let ast = rnix::parse(code);
 
     let errors = ast.errors();
     if !errors.is_empty() {
@@ -15,6 +15,5 @@ pub fn interpret(code: String) -> EvalResult<String> {
     let code = crate::compiler::compile(ast)?;
     println!("code: {:?}", code);
 
-    let value = crate::vm::run_chunk(code)?;
-    Ok(format!("value: {} :: {}", value, value.type_of()))
+    crate::vm::run_chunk(code)
 }
diff --git a/tvix/eval/src/main.rs b/tvix/eval/src/main.rs
index 4cfa0a137a..a8e2bea647 100644
--- a/tvix/eval/src/main.rs
+++ b/tvix/eval/src/main.rs
@@ -12,6 +12,9 @@ mod opcode;
 mod value;
 mod vm;
 
+#[cfg(test)]
+mod tests;
+
 fn main() {
     let mut args = env::args();
     if args.len() > 2 {
@@ -47,8 +50,8 @@ fn run_prompt() {
 }
 
 fn run(code: String) {
-    match eval::interpret(code) {
-        Ok(result) => println!("=> {}", result),
+    match eval::interpret(&code) {
+        Ok(result) => println!("=> {} :: {}", result, result.type_of()),
         Err(err) => eprintln!("{}", err),
     }
 }
diff --git a/tvix/eval/src/tests/mod.rs b/tvix/eval/src/tests/mod.rs
new file mode 100644
index 0000000000..fa56573395
--- /dev/null
+++ b/tvix/eval/src/tests/mod.rs
@@ -0,0 +1,28 @@
+use crate::eval::interpret;
+
+use test_generator::test_resources;
+
+// eval-okay-* tests contain a snippet of Nix code, and an expectation
+// of the produced string output of the evaluator.
+//
+// These evaluations are always supposed to succeed, i.e. all snippets
+// are guaranteed to be valid Nix code.
+#[test_resources("src/tests/nix_tests/eval-okay-*.nix")]
+fn eval_okay(code_path: &str) {
+    let base = code_path
+        .strip_suffix("nix")
+        .expect("test files always end in .nix");
+    let exp_path = format!("{}exp", base);
+
+    let code = std::fs::read_to_string(code_path).expect("should be able to read test code");
+    let exp = std::fs::read_to_string(exp_path).expect("should be able to read test expectation");
+
+    let result = interpret(&code).expect("evaluation of eval-okay test should succeed");
+    let result_str = format!("{}", result);
+
+    assert_eq!(
+        exp.trim(),
+        result_str,
+        "result value (and its representation) must match expectation"
+    );
+}
diff --git a/tvix/eval/src/tests/nix_tests/README.md b/tvix/eval/src/tests/nix_tests/README.md
new file mode 100644
index 0000000000..357f3547da
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/README.md
@@ -0,0 +1,8 @@
+These test definitions are taken from the Nix 2.3 code base, they can
+be found upstream at:
+
+  https://github.com/NixOS/nix/tree/2.3.16/tests/lang
+
+These tests follow the licensing directions of Nix 2.3 itself:
+
+  https://github.com/NixOS/nix/blob/2.3.16/COPYING
diff --git a/tvix/eval/src/tests/nix_tests/binary-data b/tvix/eval/src/tests/nix_tests/binary-data
new file mode 100644
index 0000000000..06d7405020
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/binary-data
Binary files differdiff --git a/tvix/eval/src/tests/nix_tests/data b/tvix/eval/src/tests/nix_tests/data
new file mode 100644
index 0000000000..257cc5642c
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/data
@@ -0,0 +1 @@
+foo
diff --git a/tvix/eval/src/tests/nix_tests/dir1/a.nix b/tvix/eval/src/tests/nix_tests/dir1/a.nix
new file mode 100644
index 0000000000..231f150c57
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/dir1/a.nix
@@ -0,0 +1 @@
+"a"
diff --git a/tvix/eval/src/tests/nix_tests/dir2/a.nix b/tvix/eval/src/tests/nix_tests/dir2/a.nix
new file mode 100644
index 0000000000..170df520ab
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/dir2/a.nix
@@ -0,0 +1 @@
+"X"
diff --git a/tvix/eval/src/tests/nix_tests/dir2/b.nix b/tvix/eval/src/tests/nix_tests/dir2/b.nix
new file mode 100644
index 0000000000..19010cc35c
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/dir2/b.nix
@@ -0,0 +1 @@
+"b"
diff --git a/tvix/eval/src/tests/nix_tests/dir3/a.nix b/tvix/eval/src/tests/nix_tests/dir3/a.nix
new file mode 100644
index 0000000000..170df520ab
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/dir3/a.nix
@@ -0,0 +1 @@
+"X"
diff --git a/tvix/eval/src/tests/nix_tests/dir3/b.nix b/tvix/eval/src/tests/nix_tests/dir3/b.nix
new file mode 100644
index 0000000000..170df520ab
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/dir3/b.nix
@@ -0,0 +1 @@
+"X"
diff --git a/tvix/eval/src/tests/nix_tests/dir3/c.nix b/tvix/eval/src/tests/nix_tests/dir3/c.nix
new file mode 100644
index 0000000000..cdf158597e
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/dir3/c.nix
@@ -0,0 +1 @@
+"c"
diff --git a/tvix/eval/src/tests/nix_tests/dir4/a.nix b/tvix/eval/src/tests/nix_tests/dir4/a.nix
new file mode 100644
index 0000000000..170df520ab
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/dir4/a.nix
@@ -0,0 +1 @@
+"X"
diff --git a/tvix/eval/src/tests/nix_tests/dir4/c.nix b/tvix/eval/src/tests/nix_tests/dir4/c.nix
new file mode 100644
index 0000000000..170df520ab
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/dir4/c.nix
@@ -0,0 +1 @@
+"X"
diff --git a/tvix/eval/src/tests/nix_tests/eval-fail-abort.nix b/tvix/eval/src/tests/nix_tests/eval-fail-abort.nix
new file mode 100644
index 0000000000..75c51bceb5
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-fail-abort.nix
@@ -0,0 +1 @@
+if true then abort "this should fail" else 1
diff --git a/tvix/eval/src/tests/nix_tests/eval-fail-antiquoted-path.nix b/tvix/eval/src/tests/nix_tests/eval-fail-antiquoted-path.nix
new file mode 100644
index 0000000000..f2f08107b5
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-fail-antiquoted-path.nix
@@ -0,0 +1,4 @@
+# This must fail to evaluate, since ./fnord doesn't exist.  If it did
+# exist, it would produce "/nix/store/<hash>-fnord/xyzzy" (with an
+# appropriate context).
+"${./fnord}/xyzzy"
diff --git a/tvix/eval/src/tests/nix_tests/eval-fail-assert.nix b/tvix/eval/src/tests/nix_tests/eval-fail-assert.nix
new file mode 100644
index 0000000000..3b7a1e8bf0
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-fail-assert.nix
@@ -0,0 +1,5 @@
+let {
+  x = arg: assert arg == "y"; 123;
+
+  body = x "x";
+}
\ No newline at end of file
diff --git a/tvix/eval/src/tests/nix_tests/eval-fail-bad-antiquote-1.nix b/tvix/eval/src/tests/nix_tests/eval-fail-bad-antiquote-1.nix
new file mode 100644
index 0000000000..ffe9c983c2
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-fail-bad-antiquote-1.nix
@@ -0,0 +1 @@
+"${x: x}"
diff --git a/tvix/eval/src/tests/nix_tests/eval-fail-bad-antiquote-2.nix b/tvix/eval/src/tests/nix_tests/eval-fail-bad-antiquote-2.nix
new file mode 100644
index 0000000000..3745235ce9
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-fail-bad-antiquote-2.nix
@@ -0,0 +1 @@
+"${./fnord}"
diff --git a/tvix/eval/src/tests/nix_tests/eval-fail-bad-antiquote-3.nix b/tvix/eval/src/tests/nix_tests/eval-fail-bad-antiquote-3.nix
new file mode 100644
index 0000000000..65b9d4f505
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-fail-bad-antiquote-3.nix
@@ -0,0 +1 @@
+''${x: x}''
diff --git a/tvix/eval/src/tests/nix_tests/eval-fail-blackhole.nix b/tvix/eval/src/tests/nix_tests/eval-fail-blackhole.nix
new file mode 100644
index 0000000000..81133b511c
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-fail-blackhole.nix
@@ -0,0 +1,5 @@
+let {
+  body = x;
+  x = y;
+  y = x;
+}
diff --git a/tvix/eval/src/tests/nix_tests/eval-fail-deepseq.nix b/tvix/eval/src/tests/nix_tests/eval-fail-deepseq.nix
new file mode 100644
index 0000000000..9baa49b063
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-fail-deepseq.nix
@@ -0,0 +1 @@
+builtins.deepSeq { x = abort "foo"; } 456
diff --git a/tvix/eval/src/tests/nix_tests/eval-fail-hashfile-missing.nix b/tvix/eval/src/tests/nix_tests/eval-fail-hashfile-missing.nix
new file mode 100644
index 0000000000..ce098b8238
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-fail-hashfile-missing.nix
@@ -0,0 +1,5 @@
+let
+  paths = [ ./this-file-is-definitely-not-there-7392097 "/and/neither/is/this/37293620" ];
+in
+  toString (builtins.concatLists (map (hash: map (builtins.hashFile hash) paths) ["md5" "sha1" "sha256" "sha512"]))
+
diff --git a/tvix/eval/src/tests/nix_tests/eval-fail-missing-arg.nix b/tvix/eval/src/tests/nix_tests/eval-fail-missing-arg.nix
new file mode 100644
index 0000000000..c4be9797c5
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-fail-missing-arg.nix
@@ -0,0 +1 @@
+({x, y, z}: x + y + z) {x = "foo"; z = "bar";}
diff --git a/tvix/eval/src/tests/nix_tests/eval-fail-path-slash.nix b/tvix/eval/src/tests/nix_tests/eval-fail-path-slash.nix
new file mode 100644
index 0000000000..8c2e104c78
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-fail-path-slash.nix
@@ -0,0 +1,6 @@
+# Trailing slashes in paths are not allowed.
+# This restriction could be lifted sometime,
+# for example if we make '/' a path concatenation operator.
+# See https://github.com/NixOS/nix/issues/1138
+# and https://nixos.org/nix-dev/2016-June/020829.html
+/nix/store/
diff --git a/tvix/eval/src/tests/nix_tests/eval-fail-remove.nix b/tvix/eval/src/tests/nix_tests/eval-fail-remove.nix
new file mode 100644
index 0000000000..539e0eb0a6
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-fail-remove.nix
@@ -0,0 +1,5 @@
+let {
+  attrs = {x = 123; y = 456;};
+
+  body = (removeAttrs attrs ["x"]).x;
+}
\ No newline at end of file
diff --git a/tvix/eval/src/tests/nix_tests/eval-fail-scope-5.nix b/tvix/eval/src/tests/nix_tests/eval-fail-scope-5.nix
new file mode 100644
index 0000000000..f89a65a99b
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-fail-scope-5.nix
@@ -0,0 +1,10 @@
+let {
+
+  x = "a";
+  y = "b";
+
+  f = {x ? y, y ? x}: x + y;
+
+  body = f {};
+
+}
diff --git a/tvix/eval/src/tests/nix_tests/eval-fail-seq.nix b/tvix/eval/src/tests/nix_tests/eval-fail-seq.nix
new file mode 100644
index 0000000000..cddbbfd326
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-fail-seq.nix
@@ -0,0 +1 @@
+builtins.seq (abort "foo") 2
diff --git a/tvix/eval/src/tests/nix_tests/eval-fail-substring.nix b/tvix/eval/src/tests/nix_tests/eval-fail-substring.nix
new file mode 100644
index 0000000000..f37c2bc0a1
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-fail-substring.nix
@@ -0,0 +1 @@
+builtins.substring (builtins.sub 0 1) 1 "x"
diff --git a/tvix/eval/src/tests/nix_tests/eval-fail-to-path.nix b/tvix/eval/src/tests/nix_tests/eval-fail-to-path.nix
new file mode 100644
index 0000000000..5e322bc313
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-fail-to-path.nix
@@ -0,0 +1 @@
+builtins.toPath "foo/bar"
diff --git a/tvix/eval/src/tests/nix_tests/eval-fail-undeclared-arg.nix b/tvix/eval/src/tests/nix_tests/eval-fail-undeclared-arg.nix
new file mode 100644
index 0000000000..cafdf16362
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-fail-undeclared-arg.nix
@@ -0,0 +1 @@
+({x, z}: x + z) {x = "foo"; y = "bla"; z = "bar";}
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-any-all.exp b/tvix/eval/src/tests/nix_tests/eval-okay-any-all.exp
new file mode 100644
index 0000000000..eb273f45b2
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-any-all.exp
@@ -0,0 +1 @@
+[ false false true true true true false true ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-any-all.nix b/tvix/eval/src/tests/nix_tests/eval-okay-any-all.nix
new file mode 100644
index 0000000000..a3f26ea2aa
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-any-all.nix
@@ -0,0 +1,11 @@
+with builtins;
+
+[ (any (x: x == 1) [])
+  (any (x: x == 1) [2 3 4])
+  (any (x: x == 1) [1 2 3 4])
+  (any (x: x == 1) [4 3 2 1])
+  (all (x: x == 1) [])
+  (all (x: x == 1) [1])
+  (all (x: x == 1) [1 2 3])
+  (all (x: x == 1) [1 1 1])
+]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-arithmetic.exp b/tvix/eval/src/tests/nix_tests/eval-okay-arithmetic.exp
new file mode 100644
index 0000000000..5c54d10b7b
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-arithmetic.exp
@@ -0,0 +1 @@
+2216
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-arithmetic.nix b/tvix/eval/src/tests/nix_tests/eval-okay-arithmetic.nix
new file mode 100644
index 0000000000..7e9e6a0b66
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-arithmetic.nix
@@ -0,0 +1,59 @@
+with import ./lib.nix;
+
+let {
+
+  /* Supposedly tail recursive version:
+
+  range_ = accum: first: last:
+    if first == last then ([first] ++ accum)
+    else range_ ([first] ++ accum) (builtins.add first 1) last;
+
+  range = range_ [];
+  */
+
+  x = 12;
+
+  err = abort "urgh";
+
+  body = sum
+    [ (sum (range 1 50))
+      (123 + 456)
+      (0 + -10 + -(-11) + -x)
+      (10 - 7 - -2)
+      (10 - (6 - -1))
+      (10 - 1 + 2)
+      (3 * 4 * 5)
+      (56088 / 123 / 2)
+      (3 + 4 * const 5 0 - 6 / id 2)
+
+      (builtins.bitAnd 12 10) # 0b1100 & 0b1010 =  8
+      (builtins.bitOr  12 10) # 0b1100 | 0b1010 = 14
+      (builtins.bitXor 12 10) # 0b1100 ^ 0b1010 =  6
+
+      (if 3 < 7 then 1 else err)
+      (if 7 < 3 then err else 1)
+      (if 3 < 3 then err else 1)
+
+      (if 3 <= 7 then 1 else err)
+      (if 7 <= 3 then err else 1)
+      (if 3 <= 3 then 1 else err)
+
+      (if 3 > 7 then err else 1)
+      (if 7 > 3 then 1 else err)
+      (if 3 > 3 then err else 1)
+
+      (if 3 >= 7 then err else 1)
+      (if 7 >= 3 then 1 else err)
+      (if 3 >= 3 then 1 else err)
+
+      (if 2 > 1 == 1 < 2 then 1 else err)
+      (if 1 + 2 * 3 >= 7 then 1 else err)
+      (if 1 + 2 * 3 < 7 then err else 1)
+
+      # Not integer, but so what.
+      (if "aa" < "ab" then 1 else err)
+      (if "aa" < "aa" then err else 1)
+      (if "foo" < "foobar" then 1 else err)
+    ];
+
+}
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-attrnames.exp b/tvix/eval/src/tests/nix_tests/eval-okay-attrnames.exp
new file mode 100644
index 0000000000..b4aa387e07
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-attrnames.exp
@@ -0,0 +1 @@
+"newxfoonewxy"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-attrnames.nix b/tvix/eval/src/tests/nix_tests/eval-okay-attrnames.nix
new file mode 100644
index 0000000000..e5b26e9f2e
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-attrnames.nix
@@ -0,0 +1,11 @@
+with import ./lib.nix;
+
+let
+
+  attrs = {y = "y"; x = "x"; foo = "foo";} // rec {x = "newx"; bar = x;};
+
+  names = builtins.attrNames attrs;
+
+  values = map (name: builtins.getAttr name attrs) names;
+
+in assert values == builtins.attrValues attrs; concat values
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-attrs.exp b/tvix/eval/src/tests/nix_tests/eval-okay-attrs.exp
new file mode 100644
index 0000000000..45b0f829eb
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-attrs.exp
@@ -0,0 +1 @@
+987
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-attrs.nix b/tvix/eval/src/tests/nix_tests/eval-okay-attrs.nix
new file mode 100644
index 0000000000..810b31a5da
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-attrs.nix
@@ -0,0 +1,5 @@
+let {
+  as = { x = 123; y = 456; } // { z = 789; } // { z = 987; };
+
+  body = if as ? a then as.a else assert as ? z; as.z;
+}
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-attrs2.exp b/tvix/eval/src/tests/nix_tests/eval-okay-attrs2.exp
new file mode 100644
index 0000000000..45b0f829eb
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-attrs2.exp
@@ -0,0 +1 @@
+987
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-attrs2.nix b/tvix/eval/src/tests/nix_tests/eval-okay-attrs2.nix
new file mode 100644
index 0000000000..9e06b83ac1
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-attrs2.nix
@@ -0,0 +1,10 @@
+let {
+  as = { x = 123; y = 456; } // { z = 789; } // { z = 987; };
+
+  A = "a";
+  Z = "z";
+
+  body = if builtins.hasAttr A as
+         then builtins.getAttr A as
+         else assert builtins.hasAttr Z as; builtins.getAttr Z as;
+}
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-attrs3.exp b/tvix/eval/src/tests/nix_tests/eval-okay-attrs3.exp
new file mode 100644
index 0000000000..19de4fdf79
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-attrs3.exp
@@ -0,0 +1 @@
+"foo 22 80 itchyxac"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-attrs3.nix b/tvix/eval/src/tests/nix_tests/eval-okay-attrs3.nix
new file mode 100644
index 0000000000..f29de11fe6
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-attrs3.nix
@@ -0,0 +1,22 @@
+let
+
+  config = 
+    {
+      services.sshd.enable = true;
+      services.sshd.port = 22;
+      services.httpd.port = 80;
+      hostName = "itchy";
+      a.b.c.d.e.f.g.h.i.j.k.l.m.n.o.p.q.r.s.t.u.v.w.x.y.z = "x";
+      foo = {
+        a = "a";
+        b.c = "c";
+      };
+    };
+
+in
+  if config.services.sshd.enable
+  then "foo ${toString config.services.sshd.port} ${toString config.services.httpd.port} ${config.hostName}"
+       + "${config.a.b.c.d.e.f.g.h.i.j.k.l.m.n.o.p.q.r.s.t.u.v.w.x.y.z}"
+       + "${config.foo.a}"
+       + "${config.foo.b.c}"
+  else "bar"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-attrs4.exp b/tvix/eval/src/tests/nix_tests/eval-okay-attrs4.exp
new file mode 100644
index 0000000000..1851731442
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-attrs4.exp
@@ -0,0 +1 @@
+[ true false true false false true false false ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-attrs4.nix b/tvix/eval/src/tests/nix_tests/eval-okay-attrs4.nix
new file mode 100644
index 0000000000..43ec81210f
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-attrs4.nix
@@ -0,0 +1,7 @@
+let
+
+  as = { x.y.z = 123; a.b.c = 456; };
+
+  bs = null;
+
+in [ (as ? x) (as ? y) (as ? x.y.z) (as ? x.y.z.a) (as ? x.y.a) (as ? a.b.c) (bs ? x) (bs ? x.y.z) ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-attrs5.exp b/tvix/eval/src/tests/nix_tests/eval-okay-attrs5.exp
new file mode 100644
index 0000000000..ce0430d780
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-attrs5.exp
@@ -0,0 +1 @@
+[ 123 "foo" 456 456 "foo" "xyzzy" "xyzzy" true ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-attrs5.nix b/tvix/eval/src/tests/nix_tests/eval-okay-attrs5.nix
new file mode 100644
index 0000000000..a4584cd3b3
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-attrs5.nix
@@ -0,0 +1,21 @@
+with import ./lib.nix;
+
+let
+
+  as = { x.y.z = 123; a.b.c = 456; };
+
+  bs = { f-o-o.bar = "foo"; };
+
+  or = x: y: x || y;
+  
+in
+  [ as.x.y.z
+    as.foo or "foo"
+    as.x.y.bla or as.a.b.c
+    as.a.b.c or as.x.y.z
+    as.x.y.bla or bs.f-o-o.bar or "xyzzy"
+    as.x.y.bla or bs.bar.foo or "xyzzy"
+    (123).bla or null.foo or "xyzzy"
+    # Backwards compatibility test.
+    (fold or [] [true false false])
+  ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-attrs6.exp b/tvix/eval/src/tests/nix_tests/eval-okay-attrs6.exp
new file mode 100644
index 0000000000..b46938032e
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-attrs6.exp
@@ -0,0 +1 @@
+{ __overrides = { bar = "qux"; }; bar = "qux"; foo = "bar"; }
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-attrs6.nix b/tvix/eval/src/tests/nix_tests/eval-okay-attrs6.nix
new file mode 100644
index 0000000000..2e5c85483b
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-attrs6.nix
@@ -0,0 +1,4 @@
+rec {
+  "${"foo"}" = "bar";
+   __overrides = { bar = "qux"; };
+}
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-autoargs.exp b/tvix/eval/src/tests/nix_tests/eval-okay-autoargs.exp
new file mode 100644
index 0000000000..7a8391786a
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-autoargs.exp
@@ -0,0 +1 @@
+"xyzzy!xyzzy!foobar"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-autoargs.flags b/tvix/eval/src/tests/nix_tests/eval-okay-autoargs.flags
new file mode 100644
index 0000000000..ae37622544
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-autoargs.flags
@@ -0,0 +1 @@
+--arg lib import(lang/lib.nix) --argstr xyzzy xyzzy! -A result
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-autoargs.nix b/tvix/eval/src/tests/nix_tests/eval-okay-autoargs.nix
new file mode 100644
index 0000000000..815f51b1d6
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-autoargs.nix
@@ -0,0 +1,15 @@
+let
+
+  foobar = "foobar";
+
+in
+
+{ xyzzy2 ? xyzzy # mutually recursive args
+, xyzzy ? "blaat" # will be overridden by --argstr
+, fb ? foobar
+, lib # will be set by --arg
+}:
+
+{
+  result = lib.concat [xyzzy xyzzy2 fb];
+}
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-backslash-newline-1.exp b/tvix/eval/src/tests/nix_tests/eval-okay-backslash-newline-1.exp
new file mode 100644
index 0000000000..3e754364cc
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-backslash-newline-1.exp
@@ -0,0 +1 @@
+"a\nb"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-backslash-newline-1.nix b/tvix/eval/src/tests/nix_tests/eval-okay-backslash-newline-1.nix
new file mode 100644
index 0000000000..7fef3dddd4
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-backslash-newline-1.nix
@@ -0,0 +1,2 @@
+"a\
+b"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-backslash-newline-2.exp b/tvix/eval/src/tests/nix_tests/eval-okay-backslash-newline-2.exp
new file mode 100644
index 0000000000..3e754364cc
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-backslash-newline-2.exp
@@ -0,0 +1 @@
+"a\nb"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-backslash-newline-2.nix b/tvix/eval/src/tests/nix_tests/eval-okay-backslash-newline-2.nix
new file mode 100644
index 0000000000..35ddf495c6
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-backslash-newline-2.nix
@@ -0,0 +1,2 @@
+''a''\
+b''
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-builtins-add.exp b/tvix/eval/src/tests/nix_tests/eval-okay-builtins-add.exp
new file mode 100644
index 0000000000..0350b518a7
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-builtins-add.exp
@@ -0,0 +1 @@
+[ 5 4 "int" "tt" "float" 4 ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-builtins-add.nix b/tvix/eval/src/tests/nix_tests/eval-okay-builtins-add.nix
new file mode 100644
index 0000000000..c841816222
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-builtins-add.nix
@@ -0,0 +1,8 @@
+[
+(builtins.add 2 3)
+(builtins.add 2 2)
+(builtins.typeOf (builtins.add 2  2))
+("t" + "t")
+(builtins.typeOf (builtins.add 2.0 2))
+(builtins.add 2.0 2)
+]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-builtins.exp b/tvix/eval/src/tests/nix_tests/eval-okay-builtins.exp
new file mode 100644
index 0000000000..0661686d61
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-builtins.exp
@@ -0,0 +1 @@
+/foo
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-builtins.nix b/tvix/eval/src/tests/nix_tests/eval-okay-builtins.nix
new file mode 100644
index 0000000000..e9d65e88a8
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-builtins.nix
@@ -0,0 +1,12 @@
+assert builtins ? currentSystem;
+assert !builtins ? __currentSystem;
+
+let {
+
+  x = if builtins ? dirOf then builtins.dirOf /foo/bar else "";
+
+  y = if builtins ? fnord then builtins.fnord "foo" else "";
+
+  body = x + y;
+  
+}
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-callable-attrs.exp b/tvix/eval/src/tests/nix_tests/eval-okay-callable-attrs.exp
new file mode 100644
index 0000000000..27ba77ddaf
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-callable-attrs.exp
@@ -0,0 +1 @@
+true
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-callable-attrs.nix b/tvix/eval/src/tests/nix_tests/eval-okay-callable-attrs.nix
new file mode 100644
index 0000000000..310a030df0
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-callable-attrs.nix
@@ -0,0 +1 @@
+({ __functor = self: x: self.foo && x; foo = false; } // { foo = true; }) true
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-catattrs.exp b/tvix/eval/src/tests/nix_tests/eval-okay-catattrs.exp
new file mode 100644
index 0000000000..b4a1e66d6b
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-catattrs.exp
@@ -0,0 +1 @@
+[ 1 2 ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-catattrs.nix b/tvix/eval/src/tests/nix_tests/eval-okay-catattrs.nix
new file mode 100644
index 0000000000..2c3dc10da5
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-catattrs.nix
@@ -0,0 +1 @@
+builtins.catAttrs "a" [ { a = 1; } { b = 0; } { a = 2; } ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-closure.exp.xml b/tvix/eval/src/tests/nix_tests/eval-okay-closure.exp.xml
new file mode 100644
index 0000000000..dffc03a998
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-closure.exp.xml
@@ -0,0 +1,343 @@
+<?xml version='1.0' encoding='utf-8'?>
+<expr>
+  <list>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="-13" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="-12" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="-11" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="-9" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="-8" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="-7" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="-5" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="-4" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="-3" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="key">
+        <int value="-1" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="0" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="1" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="2" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="4" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="5" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="6" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="key">
+        <int value="8" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="9" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="10" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="13" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="14" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="15" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="key">
+        <int value="17" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="18" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="19" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="22" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="23" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="key">
+        <int value="26" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="27" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="28" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="31" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="32" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="key">
+        <int value="35" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="36" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="40" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="41" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="key">
+        <int value="44" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="45" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="49" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="key">
+        <int value="53" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="54" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="58" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="key">
+        <int value="62" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="foo">
+        <bool value="true" />
+      </attr>
+      <attr name="key">
+        <int value="67" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="key">
+        <int value="71" />
+      </attr>
+    </attrs>
+    <attrs>
+      <attr name="key">
+        <int value="80" />
+      </attr>
+    </attrs>
+  </list>
+</expr>
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-closure.nix b/tvix/eval/src/tests/nix_tests/eval-okay-closure.nix
new file mode 100644
index 0000000000..cccd4dc357
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-closure.nix
@@ -0,0 +1,13 @@
+let
+
+  closure = builtins.genericClosure {
+    startSet = [{key = 80;}];
+    operator = {key, foo ? false}:
+      if builtins.lessThan key 0
+      then []
+      else [{key = builtins.sub key 9;} {key = builtins.sub key 13; foo = true;}];
+  };
+
+  sort = (import ./lib.nix).sortBy (a: b: builtins.lessThan a.key b.key);
+
+in sort closure
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-comments.exp b/tvix/eval/src/tests/nix_tests/eval-okay-comments.exp
new file mode 100644
index 0000000000..7182dc2f9b
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-comments.exp
@@ -0,0 +1 @@
+"abcdefghijklmnopqrstuvwxyz"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-comments.nix b/tvix/eval/src/tests/nix_tests/eval-okay-comments.nix
new file mode 100644
index 0000000000..cb2cce2180
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-comments.nix
@@ -0,0 +1,59 @@
+# A simple comment
+"a"+ # And another
+## A double comment
+"b"+  ## And another
+# Nested # comments #
+"c"+   # and # some # other #
+# An empty line, following here:
+
+"d"+      # and a comment not starting the line !
+
+"e"+
+/* multiline comments */
+"f" +
+/* multiline
+   comments,
+   on
+   multiple
+   lines
+*/
+"g" +
+# Small, tricky comments
+/**/ "h"+ /*/*/ "i"+ /***/ "j"+ /* /*/ "k"+ /*/* /*/ "l"+
+# Comments with an even number of ending '*' used to fail:
+"m"+
+/* */ /* **/ /* ***/ /* ****/ "n"+
+/* */ /** */ /*** */ /**** */ "o"+
+/** **/ /*** ***/ /**** ****/ "p"+
+/* * ** *** **** ***** */     "q"+
+# Random comments
+/* ***** ////// * / * / /* */ "r"+
+# Mixed comments
+/* # */
+"s"+
+# /* #
+"t"+
+# /* # */
+"u"+
+# /*********/
+"v"+
+## */*
+"w"+
+/*
+ * Multiline, decorated comments
+ * # This ain't a nest'd comm'nt
+ */
+"x"+
+''${/** with **/"y"
+  # real
+  /* comments
+     inside ! # */
+
+  # (and empty lines)
+
+}''+          /* And a multiline comment,
+                 on the same line,
+                 after some spaces
+*/             # followed by a one-line comment
+"z"
+/* EOF */
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-concat.exp b/tvix/eval/src/tests/nix_tests/eval-okay-concat.exp
new file mode 100644
index 0000000000..bb4bbd5774
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-concat.exp
@@ -0,0 +1 @@
+[ 1 2 3 4 5 6 7 8 9 ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-concat.nix b/tvix/eval/src/tests/nix_tests/eval-okay-concat.nix
new file mode 100644
index 0000000000..d158a9bf05
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-concat.nix
@@ -0,0 +1 @@
+[1 2 3] ++ [4 5 6] ++ [7 8 9]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-concatmap.exp b/tvix/eval/src/tests/nix_tests/eval-okay-concatmap.exp
new file mode 100644
index 0000000000..3b8be7739d
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-concatmap.exp
@@ -0,0 +1 @@
+[ [ 1 3 5 7 9 ] [ "a" "z" "b" "z" ] ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-concatmap.nix b/tvix/eval/src/tests/nix_tests/eval-okay-concatmap.nix
new file mode 100644
index 0000000000..97da5d37a4
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-concatmap.nix
@@ -0,0 +1,5 @@
+with import ./lib.nix;
+
+[ (builtins.concatMap (x: if x / 2 * 2 == x then [] else [ x ]) (range 0 10))
+  (builtins.concatMap (x: [x] ++ ["z"]) ["a" "b"])
+]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-concatstringssep.exp b/tvix/eval/src/tests/nix_tests/eval-okay-concatstringssep.exp
new file mode 100644
index 0000000000..93987647ff
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-concatstringssep.exp
@@ -0,0 +1 @@
+[ "" "foobarxyzzy" "foo, bar, xyzzy" "foo" "" ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-concatstringssep.nix b/tvix/eval/src/tests/nix_tests/eval-okay-concatstringssep.nix
new file mode 100644
index 0000000000..adc4c41bd5
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-concatstringssep.nix
@@ -0,0 +1,8 @@
+with builtins;
+
+[ (concatStringsSep "" [])
+  (concatStringsSep "" ["foo" "bar" "xyzzy"])
+  (concatStringsSep ", " ["foo" "bar" "xyzzy"])
+  (concatStringsSep ", " ["foo"])
+  (concatStringsSep ", " [])
+]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-context-introspection.exp b/tvix/eval/src/tests/nix_tests/eval-okay-context-introspection.exp
new file mode 100644
index 0000000000..27ba77ddaf
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-context-introspection.exp
@@ -0,0 +1 @@
+true
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-context-introspection.nix b/tvix/eval/src/tests/nix_tests/eval-okay-context-introspection.nix
new file mode 100644
index 0000000000..43178bd2ee
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-context-introspection.nix
@@ -0,0 +1,24 @@
+let
+  drv = derivation {
+    name = "fail";
+    builder = "/bin/false";
+    system = "x86_64-linux";
+    outputs = [ "out" "foo" ];
+  };
+
+  path = "${./eval-okay-context-introspection.nix}";
+
+  desired-context = {
+    "${builtins.unsafeDiscardStringContext path}" = {
+      path = true;
+    };
+    "${builtins.unsafeDiscardStringContext drv.drvPath}" = {
+      outputs = [ "foo" "out" ];
+      allOutputs = true;
+    };
+  };
+
+  legit-context = builtins.getContext "${path}${drv.outPath}${drv.foo.outPath}${drv.drvPath}";
+
+  constructed-context = builtins.getContext (builtins.appendContext "" desired-context);
+in legit-context == constructed-context
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-context.exp b/tvix/eval/src/tests/nix_tests/eval-okay-context.exp
new file mode 100644
index 0000000000..2f535bdbc4
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-context.exp
@@ -0,0 +1 @@
+"foo eval-okay-context.nix bar"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-context.nix b/tvix/eval/src/tests/nix_tests/eval-okay-context.nix
new file mode 100644
index 0000000000..7b9531cfe9
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-context.nix
@@ -0,0 +1,6 @@
+let s = "foo ${builtins.substring 33 100 (baseNameOf "${./eval-okay-context.nix}")} bar";
+in
+  if s != "foo eval-okay-context.nix bar"
+  then abort "context not discarded"
+  else builtins.unsafeDiscardStringContext s
+
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-curpos.exp b/tvix/eval/src/tests/nix_tests/eval-okay-curpos.exp
new file mode 100644
index 0000000000..65fd65b4d0
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-curpos.exp
@@ -0,0 +1 @@
+[ 3 7 4 9 ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-curpos.nix b/tvix/eval/src/tests/nix_tests/eval-okay-curpos.nix
new file mode 100644
index 0000000000..b79553df0b
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-curpos.nix
@@ -0,0 +1,5 @@
+# Bla
+let
+  x = __curPos;
+    y = __curPos;
+in [ x.line x.column y.line y.column ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-deepseq.exp b/tvix/eval/src/tests/nix_tests/eval-okay-deepseq.exp
new file mode 100644
index 0000000000..8d38505c16
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-deepseq.exp
@@ -0,0 +1 @@
+456
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-deepseq.nix b/tvix/eval/src/tests/nix_tests/eval-okay-deepseq.nix
new file mode 100644
index 0000000000..53aa4b1dc2
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-deepseq.nix
@@ -0,0 +1 @@
+builtins.deepSeq (let as = { x = 123; y = as; }; in as) 456
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-delayed-with-inherit.exp b/tvix/eval/src/tests/nix_tests/eval-okay-delayed-with-inherit.exp
new file mode 100644
index 0000000000..eaacb55c1a
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-delayed-with-inherit.exp
@@ -0,0 +1 @@
+"b-overridden"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-delayed-with-inherit.nix b/tvix/eval/src/tests/nix_tests/eval-okay-delayed-with-inherit.nix
new file mode 100644
index 0000000000..84b388c271
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-delayed-with-inherit.nix
@@ -0,0 +1,24 @@
+let
+  pkgs_ = with pkgs; {
+    a = derivation {
+      name = "a";
+      system = builtins.currentSystem;
+      builder = "/bin/sh";
+      args = [ "-c" "touch $out" ];
+      inherit b;
+    };
+
+    inherit b;
+  };
+
+  packageOverrides = p: {
+    b = derivation {
+      name = "b-overridden";
+      system = builtins.currentSystem;
+      builder = "/bin/sh";
+      args = [ "-c" "touch $out" ];
+    };
+  };
+
+  pkgs = pkgs_ // (packageOverrides pkgs_);
+in pkgs.a.b.name
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-delayed-with.exp b/tvix/eval/src/tests/nix_tests/eval-okay-delayed-with.exp
new file mode 100644
index 0000000000..8e7c61ab8e
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-delayed-with.exp
@@ -0,0 +1 @@
+"b-overridden b-overridden a"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-delayed-with.nix b/tvix/eval/src/tests/nix_tests/eval-okay-delayed-with.nix
new file mode 100644
index 0000000000..3fb023e1cd
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-delayed-with.nix
@@ -0,0 +1,29 @@
+let
+
+  pkgs_ = with pkgs; {
+    a = derivation {
+      name = "a";
+      system = builtins.currentSystem;
+      builder = "/bin/sh";
+      args = [ "-c" "touch $out" ];
+      inherit b;
+    };
+
+    b = derivation {
+      name = "b";
+      system = builtins.currentSystem;
+      builder = "/bin/sh";
+      args = [ "-c" "touch $out" ];
+      inherit a;
+    };
+
+    c = b;
+  };
+
+  packageOverrides = pkgs: with pkgs; {
+    b = derivation (b.drvAttrs // { name = "${b.name}-overridden"; });
+  };
+
+  pkgs = pkgs_ // (packageOverrides pkgs_);
+
+in "${pkgs.a.b.name} ${pkgs.c.name} ${pkgs.b.a.name}"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs-2.exp b/tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs-2.exp
new file mode 100644
index 0000000000..27ba77ddaf
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs-2.exp
@@ -0,0 +1 @@
+true
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs-2.nix b/tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs-2.nix
new file mode 100644
index 0000000000..6d57bf8549
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs-2.nix
@@ -0,0 +1 @@
+{ a."${"b"}" = true; a."${"c"}" = false; }.a.b
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs-bare.exp b/tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs-bare.exp
new file mode 100644
index 0000000000..df8750afc0
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs-bare.exp
@@ -0,0 +1 @@
+{ binds = true; hasAttrs = true; multiAttrs = true; recBinds = true; selectAttrs = true; selectOrAttrs = true; }
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs-bare.nix b/tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs-bare.nix
new file mode 100644
index 0000000000..0dbe15e638
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs-bare.nix
@@ -0,0 +1,17 @@
+let
+  aString = "a";
+
+  bString = "b";
+in {
+  hasAttrs = { a.b = null; } ? ${aString}.b;
+
+  selectAttrs = { a.b = true; }.a.${bString};
+
+  selectOrAttrs = { }.${aString} or true;
+
+  binds = { ${aString}."${bString}c" = true; }.a.bc;
+
+  recBinds = rec { ${bString} = a; a = true; }.b;
+
+  multiAttrs = { ${aString} = true; ${bString} = false; }.a;
+}
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs.exp b/tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs.exp
new file mode 100644
index 0000000000..df8750afc0
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs.exp
@@ -0,0 +1 @@
+{ binds = true; hasAttrs = true; multiAttrs = true; recBinds = true; selectAttrs = true; selectOrAttrs = true; }
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs.nix b/tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs.nix
new file mode 100644
index 0000000000..ee02ac7e65
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-dynamic-attrs.nix
@@ -0,0 +1,17 @@
+let
+  aString = "a";
+
+  bString = "b";
+in {
+  hasAttrs = { a.b = null; } ? "${aString}".b;
+
+  selectAttrs = { a.b = true; }.a."${bString}";
+
+  selectOrAttrs = { }."${aString}" or true;
+
+  binds = { "${aString}"."${bString}c" = true; }.a.bc;
+
+  recBinds = rec { "${bString}" = a; a = true; }.b;
+
+  multiAttrs = { "${aString}" = true; "${bString}" = false; }.a;
+}
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-elem.exp b/tvix/eval/src/tests/nix_tests/eval-okay-elem.exp
new file mode 100644
index 0000000000..3cf6c0e962
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-elem.exp
@@ -0,0 +1 @@
+[ true false 30 ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-elem.nix b/tvix/eval/src/tests/nix_tests/eval-okay-elem.nix
new file mode 100644
index 0000000000..71ea7a4ed0
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-elem.nix
@@ -0,0 +1,6 @@
+with import ./lib.nix;
+
+let xs = range 10 40; in
+
+[ (builtins.elem 23 xs) (builtins.elem 42 xs) (builtins.elemAt xs 20) ]
+
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-empty-args.exp b/tvix/eval/src/tests/nix_tests/eval-okay-empty-args.exp
new file mode 100644
index 0000000000..cb5537d5d7
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-empty-args.exp
@@ -0,0 +1 @@
+"ab"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-empty-args.nix b/tvix/eval/src/tests/nix_tests/eval-okay-empty-args.nix
new file mode 100644
index 0000000000..78c133afdd
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-empty-args.nix
@@ -0,0 +1 @@
+({}: {x,y,}: "${x}${y}") {} {x = "a"; y = "b";}
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-eq-derivations.exp b/tvix/eval/src/tests/nix_tests/eval-okay-eq-derivations.exp
new file mode 100644
index 0000000000..ec04aab6ae
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-eq-derivations.exp
@@ -0,0 +1 @@
+[ true true true false ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-eq-derivations.nix b/tvix/eval/src/tests/nix_tests/eval-okay-eq-derivations.nix
new file mode 100644
index 0000000000..d526cb4a21
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-eq-derivations.nix
@@ -0,0 +1,10 @@
+let
+
+  drvA1 = derivation { name = "a"; builder = "/foo"; system = "i686-linux"; };
+  drvA2 = derivation { name = "a"; builder = "/foo"; system = "i686-linux"; };
+  drvA3 = derivation { name = "a"; builder = "/foo"; system = "i686-linux"; } // { dummy = 1; };
+  
+  drvC1 = derivation { name = "c"; builder = "/foo"; system = "i686-linux"; };
+  drvC2 = derivation { name = "c"; builder = "/bar"; system = "i686-linux"; };
+
+in [ (drvA1 == drvA1) (drvA1 == drvA2) (drvA1 == drvA3) (drvC1 == drvC2) ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-eq.exp.disabled b/tvix/eval/src/tests/nix_tests/eval-okay-eq.exp.disabled
new file mode 100644
index 0000000000..2015847b65
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-eq.exp.disabled
@@ -0,0 +1 @@
+Bool(True)
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-eq.nix b/tvix/eval/src/tests/nix_tests/eval-okay-eq.nix
new file mode 100644
index 0000000000..73d200b381
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-eq.nix
@@ -0,0 +1,3 @@
+["foobar" (rec {x = 1; y = x;})]
+==
+[("foo" + "bar") ({x = 1; y = 1;})]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-filter.exp b/tvix/eval/src/tests/nix_tests/eval-okay-filter.exp
new file mode 100644
index 0000000000..355d51c27d
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-filter.exp
@@ -0,0 +1 @@
+[ 0 2 4 6 8 10 100 102 104 106 108 110 ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-filter.nix b/tvix/eval/src/tests/nix_tests/eval-okay-filter.nix
new file mode 100644
index 0000000000..85109b0d0e
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-filter.nix
@@ -0,0 +1,5 @@
+with import ./lib.nix;
+
+builtins.filter
+  (x: x / 2 * 2 == x)
+  (builtins.concatLists [ (range 0 10) (range 100 110) ])
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-flatten.exp b/tvix/eval/src/tests/nix_tests/eval-okay-flatten.exp
new file mode 100644
index 0000000000..b979b2b8b9
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-flatten.exp
@@ -0,0 +1 @@
+"1234567"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-flatten.nix b/tvix/eval/src/tests/nix_tests/eval-okay-flatten.nix
new file mode 100644
index 0000000000..fe911e9683
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-flatten.nix
@@ -0,0 +1,8 @@
+with import ./lib.nix;
+
+let {
+
+  l = ["1" "2" ["3" ["4"] ["5" "6"]] "7"];
+
+  body = concat (flatten l);
+}
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-float.exp b/tvix/eval/src/tests/nix_tests/eval-okay-float.exp
new file mode 100644
index 0000000000..3c50a8adce
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-float.exp
@@ -0,0 +1 @@
+[ 3.4 3.5 2.5 1.5 ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-float.nix b/tvix/eval/src/tests/nix_tests/eval-okay-float.nix
new file mode 100644
index 0000000000..b2702c7b16
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-float.nix
@@ -0,0 +1,6 @@
+[
+  (1.1 + 2.3)
+  (builtins.add (0.5 + 0.5) (2.0 + 0.5))
+  ((0.5 + 0.5) * (2.0 + 0.5))
+  ((1.5 + 1.5) / (0.5 * 4.0))
+]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-fromTOML.exp b/tvix/eval/src/tests/nix_tests/eval-okay-fromTOML.exp
new file mode 100644
index 0000000000..d0dd3af2c8
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-fromTOML.exp
@@ -0,0 +1 @@
+[ { clients = { data = [ [ "gamma" "delta" ] [ 1 2 ] ]; hosts = [ "alpha" "omega" ]; }; database = { connection_max = 5000; enabled = true; ports = [ 8001 8001 8002 ]; server = "192.168.1.1"; }; owner = { name = "Tom Preston-Werner"; }; servers = { alpha = { dc = "eqdc10"; ip = "10.0.0.1"; }; beta = { dc = "eqdc10"; ip = "10.0.0.2"; }; }; title = "TOML Example"; } { "1234" = "value"; "127.0.0.1" = "value"; a = { b = { c = { }; }; }; arr1 = [ 1 2 3 ]; arr2 = [ "red" "yellow" "green" ]; arr3 = [ [ 1 2 ] [ 3 4 5 ] ]; arr4 = [ "all" "strings" "are the same" "type" ]; arr5 = [ [ 1 2 ] [ "a" "b" "c" ] ]; arr7 = [ 1 2 3 ]; arr8 = [ 1 2 ]; bare-key = "value"; bare_key = "value"; bin1 = 214; bool1 = true; bool2 = false; "character encoding" = "value"; d = { e = { f = { }; }; }; dog = { "tater.man" = { type = { name = "pug"; }; }; }; flt1 = 1; flt2 = 3.1415; flt3 = -0.01; flt4 = 5e+22; flt5 = 1e+06; flt6 = -0.02; flt7 = 6.626e-34; flt8 = 9.22462e+06; fruit = [ { name = "apple"; physical = { color = "red"; shape = "round"; }; variety = [ { name = "red delicious"; } { name = "granny smith"; } ]; } { name = "banana"; variety = [ { name = "plantain"; } ]; } ]; g = { h = { i = { }; }; }; hex1 = 3735928559; hex2 = 3735928559; hex3 = 3735928559; int1 = 99; int2 = 42; int3 = 0; int4 = -17; int5 = 1000; int6 = 5349221; int7 = 12345; j = { "ʞ" = { l = { }; }; }; key = "value"; key2 = "value"; name = "Orange"; oct1 = 342391; oct2 = 493; physical = { color = "orange"; shape = "round"; }; products = [ { name = "Hammer"; sku = 738594937; } { } { color = "gray"; name = "Nail"; sku = 284758393; } ]; "quoted \"value\"" = "value"; site = { "google.com" = true; }; str = "I'm a string. \"You can quote me\". Name\tJosé\nLocation\tSF."; table-1 = { key1 = "some string"; key2 = 123; }; table-2 = { key1 = "another string"; key2 = 456; }; x = { y = { z = { w = { animal = { type = { name = "pug"; }; }; name = { first = "Tom"; last = "Preston-Werner"; }; point = { x = 1; y = 2; }; }; }; }; }; "ʎǝʞ" = "value"; } { metadata = { "checksum aho-corasick 0.6.4 (registry+https://github.com/rust-lang/crates.io-index)" = "d6531d44de723825aa81398a6415283229725a00fa30713812ab9323faa82fc4"; "checksum ansi_term 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ee49baf6cb617b853aa8d93bf420db2383fab46d314482ca2803b40d5fde979b"; "checksum ansi_term 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "23ac7c30002a5accbf7e8987d0632fa6de155b7c3d39d0067317a391e00a2ef6"; "checksum arrayvec 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)" = "a1e964f9e24d588183fcb43503abda40d288c8657dfc27311516ce2f05675aef"; }; package = [ { dependencies = [ "memchr 2.0.1 (registry+https://github.com/rust-lang/crates.io-index)" ]; name = "aho-corasick"; source = "registry+https://github.com/rust-lang/crates.io-index"; version = "0.6.4"; } { name = "ansi_term"; source = "registry+https://github.com/rust-lang/crates.io-index"; version = "0.9.0"; } { dependencies = [ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)" "termion 1.5.1 (registry+https://github.com/rust-lang/crates.io-index)" "winapi 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)" ]; name = "atty"; source = "registry+https://github.com/rust-lang/crates.io-index"; version = "0.2.10"; } ]; } { a = [ [ { b = true; } ] ]; c = [ [ { d = true; } ] ]; e = [ [ 123 ] ]; } ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-fromTOML.nix b/tvix/eval/src/tests/nix_tests/eval-okay-fromTOML.nix
new file mode 100644
index 0000000000..9639326899
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-fromTOML.nix
@@ -0,0 +1,208 @@
+[
+
+  (builtins.fromTOML ''
+    # This is a TOML document.
+
+    title = "TOML Example"
+
+    [owner]
+    name = "Tom Preston-Werner"
+    #dob = 1979-05-27T07:32:00-08:00 # First class dates
+
+    [database]
+    server = "192.168.1.1"
+    ports = [ 8001, 8001, 8002 ]
+    connection_max = 5000
+    enabled = true
+
+    [servers]
+
+      # Indentation (tabs and/or spaces) is allowed but not required
+      [servers.alpha]
+      ip = "10.0.0.1"
+      dc = "eqdc10"
+
+      [servers.beta]
+      ip = "10.0.0.2"
+      dc = "eqdc10"
+
+    [clients]
+    data = [ ["gamma", "delta"], [1, 2] ]
+
+    # Line breaks are OK when inside arrays
+    hosts = [
+      "alpha",
+      "omega"
+    ]
+  '')
+
+  (builtins.fromTOML ''
+    key = "value"
+    bare_key = "value"
+    bare-key = "value"
+    1234 = "value"
+
+    "127.0.0.1" = "value"
+    "character encoding" = "value"
+    "ʎǝʞ" = "value"
+    'key2' = "value"
+    'quoted "value"' = "value"
+
+    name = "Orange"
+
+    physical.color = "orange"
+    physical.shape = "round"
+    site."google.com" = true
+
+    # This is legal according to the spec, but cpptoml doesn't handle it.
+    #a.b.c = 1
+    #a.d = 2
+
+    str = "I'm a string. \"You can quote me\". Name\tJos\u00E9\nLocation\tSF."
+
+    int1 = +99
+    int2 = 42
+    int3 = 0
+    int4 = -17
+    int5 = 1_000
+    int6 = 5_349_221
+    int7 = 1_2_3_4_5
+
+    hex1 = 0xDEADBEEF
+    hex2 = 0xdeadbeef
+    hex3 = 0xdead_beef
+
+    oct1 = 0o01234567
+    oct2 = 0o755
+
+    bin1 = 0b11010110
+
+    flt1 = +1.0
+    flt2 = 3.1415
+    flt3 = -0.01
+    flt4 = 5e+22
+    flt5 = 1e6
+    flt6 = -2E-2
+    flt7 = 6.626e-34
+    flt8 = 9_224_617.445_991_228_313
+
+    bool1 = true
+    bool2 = false
+
+    # FIXME: not supported because Nix doesn't have a date/time type.
+    #odt1 = 1979-05-27T07:32:00Z
+    #odt2 = 1979-05-27T00:32:00-07:00
+    #odt3 = 1979-05-27T00:32:00.999999-07:00
+    #odt4 = 1979-05-27 07:32:00Z
+    #ldt1 = 1979-05-27T07:32:00
+    #ldt2 = 1979-05-27T00:32:00.999999
+    #ld1 = 1979-05-27
+    #lt1 = 07:32:00
+    #lt2 = 00:32:00.999999
+
+    arr1 = [ 1, 2, 3 ]
+    arr2 = [ "red", "yellow", "green" ]
+    arr3 = [ [ 1, 2 ], [3, 4, 5] ]
+    arr4 = [ "all", 'strings', """are the same""", ''''type'''']
+    arr5 = [ [ 1, 2 ], ["a", "b", "c"] ]
+
+    arr7 = [
+      1, 2, 3
+    ]
+
+    arr8 = [
+      1,
+      2, # this is ok
+    ]
+
+    [table-1]
+    key1 = "some string"
+    key2 = 123
+
+
+    [table-2]
+    key1 = "another string"
+    key2 = 456
+
+    [dog."tater.man"]
+    type.name = "pug"
+
+    [a.b.c]
+    [ d.e.f ]
+    [ g .  h  . i ]
+    [ j . "ʞ" . 'l' ]
+    [x.y.z.w]
+
+    name = { first = "Tom", last = "Preston-Werner" }
+    point = { x = 1, y = 2 }
+    animal = { type.name = "pug" }
+
+    [[products]]
+    name = "Hammer"
+    sku = 738594937
+
+    [[products]]
+
+    [[products]]
+    name = "Nail"
+    sku = 284758393
+    color = "gray"
+
+    [[fruit]]
+      name = "apple"
+
+      [fruit.physical]
+        color = "red"
+        shape = "round"
+
+      [[fruit.variety]]
+        name = "red delicious"
+
+      [[fruit.variety]]
+        name = "granny smith"
+
+    [[fruit]]
+      name = "banana"
+
+      [[fruit.variety]]
+        name = "plantain"
+  '')
+
+  (builtins.fromTOML ''
+    [[package]]
+    name = "aho-corasick"
+    version = "0.6.4"
+    source = "registry+https://github.com/rust-lang/crates.io-index"
+    dependencies = [
+     "memchr 2.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
+    ]
+
+    [[package]]
+    name = "ansi_term"
+    version = "0.9.0"
+    source = "registry+https://github.com/rust-lang/crates.io-index"
+
+    [[package]]
+    name = "atty"
+    version = "0.2.10"
+    source = "registry+https://github.com/rust-lang/crates.io-index"
+    dependencies = [
+     "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
+     "termion 1.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
+     "winapi 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
+    ]
+
+    [metadata]
+    "checksum aho-corasick 0.6.4 (registry+https://github.com/rust-lang/crates.io-index)" = "d6531d44de723825aa81398a6415283229725a00fa30713812ab9323faa82fc4"
+    "checksum ansi_term 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ee49baf6cb617b853aa8d93bf420db2383fab46d314482ca2803b40d5fde979b"
+    "checksum ansi_term 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "23ac7c30002a5accbf7e8987d0632fa6de155b7c3d39d0067317a391e00a2ef6"
+    "checksum arrayvec 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)" = "a1e964f9e24d588183fcb43503abda40d288c8657dfc27311516ce2f05675aef"
+  '')
+
+  (builtins.fromTOML ''
+    a = [[{ b = true }]]
+    c = [ [ { d = true } ] ]
+    e = [[123]]
+  '')
+
+]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-fromjson-escapes.exp b/tvix/eval/src/tests/nix_tests/eval-okay-fromjson-escapes.exp
new file mode 100644
index 0000000000..add5505a82
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-fromjson-escapes.exp
@@ -0,0 +1 @@
+"quote \" reverse solidus \\ solidus / backspace  formfeed  newline \n carriage return \r horizontal tab \t 1 char unicode encoded backspace  1 char unicode encoded e with accent é 2 char unicode encoded s with caron š 3 char unicode encoded rightwards arrow →"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-fromjson-escapes.nix b/tvix/eval/src/tests/nix_tests/eval-okay-fromjson-escapes.nix
new file mode 100644
index 0000000000..f007135077
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-fromjson-escapes.nix
@@ -0,0 +1,3 @@
+# This string contains all supported escapes in a JSON string, per json.org
+# \b and \f are not supported by Nix
+builtins.fromJSON ''"quote \" reverse solidus \\ solidus \/ backspace \b formfeed \f newline \n carriage return \r horizontal tab \t 1 char unicode encoded backspace \u0008 1 char unicode encoded e with accent \u00e9 2 char unicode encoded s with caron \u0161 3 char unicode encoded rightwards arrow \u2192"''
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-fromjson.exp b/tvix/eval/src/tests/nix_tests/eval-okay-fromjson.exp
new file mode 100644
index 0000000000..27ba77ddaf
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-fromjson.exp
@@ -0,0 +1 @@
+true
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-fromjson.nix b/tvix/eval/src/tests/nix_tests/eval-okay-fromjson.nix
new file mode 100644
index 0000000000..102ee82b5e
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-fromjson.nix
@@ -0,0 +1,36 @@
+# RFC 7159, section 13.
+builtins.fromJSON
+  ''
+    {
+      "Image": {
+          "Width":  800,
+          "Height": 600,
+          "Title":  "View from 15th Floor",
+          "Thumbnail": {
+              "Url":    "http://www.example.com/image/481989943",
+              "Height": 125,
+              "Width":  100
+          },
+          "Animated" : false,
+          "IDs": [116, 943, 234, 38793, true  ,false,null, -100],
+          "Latitude":  37.7668,
+          "Longitude": -122.3959
+        }
+    }
+  ''
+==
+  { Image =
+    { Width = 800;
+      Height = 600;
+      Title = "View from 15th Floor";
+      Thumbnail =
+        { Url = http://www.example.com/image/481989943;
+          Height = 125;
+          Width = 100;
+        };
+      Animated = false;
+      IDs = [ 116 943 234 38793 true false null (0-100) ];
+      Latitude = 37.7668;
+      Longitude = -122.3959;
+    };
+  }
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-functionargs.exp.xml b/tvix/eval/src/tests/nix_tests/eval-okay-functionargs.exp.xml
new file mode 100644
index 0000000000..651f54c363
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-functionargs.exp.xml
@@ -0,0 +1,15 @@
+<?xml version='1.0' encoding='utf-8'?>
+<expr>
+  <list>
+    <string value="stdenv" />
+    <string value="fetchurl" />
+    <string value="aterm-stdenv" />
+    <string value="aterm-stdenv2" />
+    <string value="libX11" />
+    <string value="libXv" />
+    <string value="mplayer-stdenv2.libXv-libX11" />
+    <string value="mplayer-stdenv2.libXv-libX11_2" />
+    <string value="nix-stdenv-aterm-stdenv" />
+    <string value="nix-stdenv2-aterm2-stdenv2" />
+  </list>
+</expr>
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-functionargs.nix b/tvix/eval/src/tests/nix_tests/eval-okay-functionargs.nix
new file mode 100644
index 0000000000..68dca62ee1
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-functionargs.nix
@@ -0,0 +1,80 @@
+let
+
+  stdenvFun = { }: { name = "stdenv"; };
+  stdenv2Fun = { }: { name = "stdenv2"; };
+  fetchurlFun = { stdenv }: assert stdenv.name == "stdenv"; { name = "fetchurl"; };
+  atermFun = { stdenv, fetchurl }: { name = "aterm-${stdenv.name}"; };
+  aterm2Fun = { stdenv, fetchurl }: { name = "aterm2-${stdenv.name}"; };
+  nixFun = { stdenv, fetchurl, aterm }: { name = "nix-${stdenv.name}-${aterm.name}"; };
+  
+  mplayerFun =
+    { stdenv, fetchurl, enableX11 ? false, xorg ? null, enableFoo ? true, foo ? null  }:
+    assert stdenv.name == "stdenv2";
+    assert enableX11 -> xorg.libXv.name == "libXv";
+    assert enableFoo -> foo != null;
+    { name = "mplayer-${stdenv.name}.${xorg.libXv.name}-${xorg.libX11.name}"; };
+
+  makeOverridable = f: origArgs: f origArgs //
+    { override = newArgs:
+        makeOverridable f (origArgs // (if builtins.isFunction newArgs then newArgs origArgs else newArgs));
+    };
+    
+  callPackage_ = pkgs: f: args:
+    makeOverridable f ((builtins.intersectAttrs (builtins.functionArgs f) pkgs) // args);
+
+  allPackages =
+    { overrides ? (pkgs: pkgsPrev: { }) }:
+    let
+      callPackage = callPackage_ pkgs;
+      pkgs = pkgsStd // (overrides pkgs pkgsStd);
+      pkgsStd = {
+        inherit pkgs;
+        stdenv = callPackage stdenvFun { };
+        stdenv2 = callPackage stdenv2Fun { };
+        fetchurl = callPackage fetchurlFun { };
+        aterm = callPackage atermFun { };
+        xorg = callPackage xorgFun { };
+        mplayer = callPackage mplayerFun { stdenv = pkgs.stdenv2; enableFoo = false; };
+        nix = callPackage nixFun { };
+      };
+    in pkgs;
+
+  libX11Fun = { stdenv, fetchurl }: { name = "libX11"; };
+  libX11_2Fun = { stdenv, fetchurl }: { name = "libX11_2"; };
+  libXvFun = { stdenv, fetchurl, libX11 }: { name = "libXv"; };
+  
+  xorgFun =
+    { pkgs }:
+    let callPackage = callPackage_ (pkgs // pkgs.xorg); in
+    {
+      libX11 = callPackage libX11Fun { };
+      libXv = callPackage libXvFun { };
+    };
+
+in
+
+let
+
+  pkgs = allPackages { };
+  
+  pkgs2 = allPackages {
+    overrides = pkgs: pkgsPrev: {
+      stdenv = pkgs.stdenv2;
+      nix = pkgsPrev.nix.override { aterm = aterm2Fun { inherit (pkgs) stdenv fetchurl; }; };
+      xorg = pkgsPrev.xorg // { libX11 = libX11_2Fun { inherit (pkgs) stdenv fetchurl; }; };
+    };
+  };
+  
+in
+
+  [ pkgs.stdenv.name
+    pkgs.fetchurl.name
+    pkgs.aterm.name
+    pkgs2.aterm.name
+    pkgs.xorg.libX11.name
+    pkgs.xorg.libXv.name
+    pkgs.mplayer.name
+    pkgs2.mplayer.name
+    pkgs.nix.name
+    pkgs2.nix.name
+  ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-getattrpos-undefined.exp b/tvix/eval/src/tests/nix_tests/eval-okay-getattrpos-undefined.exp
new file mode 100644
index 0000000000..19765bd501
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-getattrpos-undefined.exp
@@ -0,0 +1 @@
+null
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-getattrpos-undefined.nix b/tvix/eval/src/tests/nix_tests/eval-okay-getattrpos-undefined.nix
new file mode 100644
index 0000000000..14dd38f773
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-getattrpos-undefined.nix
@@ -0,0 +1 @@
+builtins.unsafeGetAttrPos "abort" builtins
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-getattrpos.exp b/tvix/eval/src/tests/nix_tests/eval-okay-getattrpos.exp
new file mode 100644
index 0000000000..469249bbc6
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-getattrpos.exp
@@ -0,0 +1 @@
+{ column = 5; file = "eval-okay-getattrpos.nix"; line = 3; }
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-getattrpos.nix b/tvix/eval/src/tests/nix_tests/eval-okay-getattrpos.nix
new file mode 100644
index 0000000000..ca6b079615
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-getattrpos.nix
@@ -0,0 +1,6 @@
+let
+  as = {
+    foo = "bar";
+  };
+  pos = builtins.unsafeGetAttrPos "foo" as;
+in { inherit (pos) column line; file = baseNameOf pos.file; }
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-getenv.exp b/tvix/eval/src/tests/nix_tests/eval-okay-getenv.exp
new file mode 100644
index 0000000000..14e24d4190
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-getenv.exp
@@ -0,0 +1 @@
+"foobar"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-getenv.nix b/tvix/eval/src/tests/nix_tests/eval-okay-getenv.nix
new file mode 100644
index 0000000000..4cfec5f553
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-getenv.nix
@@ -0,0 +1 @@
+builtins.getEnv "TEST_VAR" + (if builtins.getEnv "NO_SUCH_VAR" == "" then "bar" else "bla")
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-hash.exp b/tvix/eval/src/tests/nix_tests/eval-okay-hash.exp
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-hash.exp
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-hashfile.exp b/tvix/eval/src/tests/nix_tests/eval-okay-hashfile.exp
new file mode 100644
index 0000000000..ff1e8293ef
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-hashfile.exp
@@ -0,0 +1 @@
+[ "d3b07384d113edec49eaa6238ad5ff00" "0f343b0931126a20f133d67c2b018a3b" "f1d2d2f924e986ac86fdf7b36c94bcdf32beec15" "60cacbf3d72e1e7834203da608037b1bf83b40e8" "b5bb9d8014a0f9b1d61e21e796d78dccdf1352f23cd32812f4850b878ae4944c" "5f70bf18a086007016e948b04aed3b82103a36bea41755b6cddfaf10ace3c6ef" "0cf9180a764aba863a67b6d72f0918bc131c6772642cb2dce5a34f0a702f9470ddc2bf125c12198b1995c233c34b4afd346c54a2334c350a948a51b6e8b4e6b6" "8efb4f73c5655351c444eb109230c556d39e2c7624e9c11abc9e3fb4b9b9254218cc5085b454a9698d085cfa92198491f07a723be4574adc70617b73eb0b6461" ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-hashfile.nix b/tvix/eval/src/tests/nix_tests/eval-okay-hashfile.nix
new file mode 100644
index 0000000000..aff5a18568
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-hashfile.nix
@@ -0,0 +1,4 @@
+let
+  paths = [ ./data ./binary-data ];
+in
+  builtins.concatLists (map (hash: map (builtins.hashFile hash) paths) ["md5" "sha1" "sha256" "sha512"])
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-hashstring.exp b/tvix/eval/src/tests/nix_tests/eval-okay-hashstring.exp
new file mode 100644
index 0000000000..d720a082dd
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-hashstring.exp
@@ -0,0 +1 @@
+[ "d41d8cd98f00b204e9800998ecf8427e" "6c69ee7f211c640419d5366cc076ae46" "bb3438fbabd460ea6dbd27d153e2233b" "da39a3ee5e6b4b0d3255bfef95601890afd80709" "cd54e8568c1b37cf1e5badb0779bcbf382212189" "6d12e10b1d331dad210e47fd25d4f260802b7e77" "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855" "900a4469df00ccbfd0c145c6d1e4b7953dd0afafadd7534e3a4019e8d38fc663" "ad0387b3bd8652f730ca46d25f9c170af0fd589f42e7f23f5a9e6412d97d7e56" "cf83e1357eefb8bdf1542850d66d8007d620e4050b5715dc83f4a921d36ce9ce47d0d13c5d85f2b0ff8318d2877eec2f63b931bd47417a81a538327af927da3e" "9d0886f8c6b389398a16257bc79780fab9831c7fc11c8ab07fa732cb7b348feade382f92617c9c5305fefba0af02ab5fd39a587d330997ff5bd0db19f7666653" "21644b72aa259e5a588cd3afbafb1d4310f4889680f6c83b9d531596a5a284f34dbebff409d23bcc86aee6bad10c891606f075c6f4755cb536da27db5693f3a7" ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-hashstring.nix b/tvix/eval/src/tests/nix_tests/eval-okay-hashstring.nix
new file mode 100644
index 0000000000..b0f62b245c
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-hashstring.nix
@@ -0,0 +1,4 @@
+let
+  strings = [ "" "text 1" "text 2" ];
+in
+  builtins.concatLists (map (hash: map (builtins.hashString hash) strings) ["md5" "sha1" "sha256" "sha512"])
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-if.exp b/tvix/eval/src/tests/nix_tests/eval-okay-if.exp
new file mode 100644
index 0000000000..00750edc07
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-if.exp
@@ -0,0 +1 @@
+3
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-if.nix b/tvix/eval/src/tests/nix_tests/eval-okay-if.nix
new file mode 100644
index 0000000000..23e4c74d50
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-if.nix
@@ -0,0 +1 @@
+if "foo" != "f" + "oo" then 1 else if false then 2 else 3
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-import.exp b/tvix/eval/src/tests/nix_tests/eval-okay-import.exp
new file mode 100644
index 0000000000..c508125b55
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-import.exp
@@ -0,0 +1 @@
+[ 1 2 3 4 5 6 7 8 9 10 ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-import.nix b/tvix/eval/src/tests/nix_tests/eval-okay-import.nix
new file mode 100644
index 0000000000..0b18d94131
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-import.nix
@@ -0,0 +1,11 @@
+let
+
+  overrides = {
+    import = fn: scopedImport overrides fn;
+
+    scopedImport = attrs: fn: scopedImport (overrides // attrs) fn;
+
+    builtins = builtins // overrides;
+  } // import ./lib.nix;
+
+in scopedImport overrides ./imported.nix
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-ind-string.exp b/tvix/eval/src/tests/nix_tests/eval-okay-ind-string.exp
new file mode 100644
index 0000000000..9cf4bd2ee7
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-ind-string.exp
@@ -0,0 +1 @@
+"This is an indented multi-line string\nliteral.  An amount of whitespace at\nthe start of each line matching the minimum\nindentation of all lines in the string\nliteral together will be removed.  Thus,\nin this case four spaces will be\nstripped from each line, even though\n  THIS LINE is indented six spaces.\n\nAlso, empty lines don't count in the\ndetermination of the indentation level (the\nprevious empty line has indentation 0, but\nit doesn't matter).\nIf the string starts with whitespace\n  followed by a newline, it's stripped, but\n  that's not the case here. Two spaces are\n  stripped because of the \"  \" at the start. \nThis line is indented\na bit further.\nAnti-quotations, like so, are\nalso allowed.\n  The \\ is not special here.\n' can be followed by any character except another ', e.g. 'x'.\nLikewise for $, e.g. $$ or $varName.\nBut ' followed by ' is special, as is $ followed by {.\nIf you want them, use anti-quotations: '', ${.\n   Tabs are not interpreted as whitespace (since we can't guess\n   what tab settings are intended), so don't use them.\n\tThis line starts with a space and a tab, so only one\n   space will be stripped from each line.\nAlso note that if the last line (just before the closing ' ')\nconsists only of whitespace, it's ignored.  But here there is\nsome non-whitespace stuff, so the line isn't removed. \nThis shows a hacky way to preserve an empty line after the start.\nBut there's no reason to do so: you could just repeat the empty\nline.\n  Similarly you can force an indentation level,\n  in this case to 2 spaces.  This works because the anti-quote\n  is significant (not whitespace).\nstart on network-interfaces\n\nstart script\n\n  rm -f /var/run/opengl-driver\n  ln -sf 123 /var/run/opengl-driver\n\n  rm -f /var/log/slim.log\n   \nend script\n\nenv SLIM_CFGFILE=abc\nenv SLIM_THEMESDIR=def\nenv FONTCONFIG_FILE=/etc/fonts/fonts.conf  \t\t\t\t# !!! cleanup\nenv XKB_BINDIR=foo/bin         \t\t\t\t# Needed for the Xkb extension.\nenv LD_LIBRARY_PATH=libX11/lib:libXext/lib:/usr/lib/          # related to xorg-sys-opengl - needed to load libglx for (AI)GLX support (for compiz)\n\nenv XORG_DRI_DRIVER_PATH=nvidiaDrivers/X11R6/lib/modules/drivers/ \n\nexec slim/bin/slim\nEscaping of ' followed by ': ''\nEscaping of $ followed by {: ${\nAnd finally to interpret \\n etc. as in a string: \n, \r, \t.\nfoo\n'bla'\nbar\ncut -d $'\\t' -f 1\nending dollar $$\n"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-ind-string.nix b/tvix/eval/src/tests/nix_tests/eval-okay-ind-string.nix
new file mode 100644
index 0000000000..1669dc0648
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-ind-string.nix
@@ -0,0 +1,128 @@
+let
+
+  s1 = ''
+    This is an indented multi-line string
+    literal.  An amount of whitespace at
+    the start of each line matching the minimum
+    indentation of all lines in the string
+    literal together will be removed.  Thus,
+    in this case four spaces will be
+    stripped from each line, even though
+      THIS LINE is indented six spaces.
+
+    Also, empty lines don't count in the
+    determination of the indentation level (the
+    previous empty line has indentation 0, but
+    it doesn't matter).
+  '';
+
+  s2 = ''  If the string starts with whitespace
+    followed by a newline, it's stripped, but
+    that's not the case here. Two spaces are
+    stripped because of the "  " at the start. 
+  '';
+
+  s3 = ''
+      This line is indented
+      a bit further.
+        ''; # indentation of last line doesn't count if it's empty
+
+  s4 = ''
+    Anti-quotations, like ${if true then "so" else "not so"}, are
+    also allowed.
+  '';
+
+  s5 = ''
+      The \ is not special here.
+    ' can be followed by any character except another ', e.g. 'x'.
+    Likewise for $, e.g. $$ or $varName.
+    But ' followed by ' is special, as is $ followed by {.
+    If you want them, use anti-quotations: ${"''"}, ${"\${"}.
+  '';
+
+  s6 = ''  
+    Tabs are not interpreted as whitespace (since we can't guess
+    what tab settings are intended), so don't use them.
+ 	This line starts with a space and a tab, so only one
+    space will be stripped from each line.
+  '';
+
+  s7 = ''
+    Also note that if the last line (just before the closing ' ')
+    consists only of whitespace, it's ignored.  But here there is
+    some non-whitespace stuff, so the line isn't removed. '';
+
+  s8 = ''    ${""}
+    This shows a hacky way to preserve an empty line after the start.
+    But there's no reason to do so: you could just repeat the empty
+    line.
+  '';
+
+  s9 = ''
+  ${""}  Similarly you can force an indentation level,
+    in this case to 2 spaces.  This works because the anti-quote
+    is significant (not whitespace).
+  '';
+
+  s10 = ''
+  '';
+
+  s11 = '''';
+
+  s12 = ''   '';
+
+  s13 = ''
+    start on network-interfaces
+
+    start script
+    
+      rm -f /var/run/opengl-driver
+      ${if true
+        then "ln -sf 123 /var/run/opengl-driver"
+        else if true
+        then "ln -sf 456 /var/run/opengl-driver"
+        else ""
+      }
+
+      rm -f /var/log/slim.log
+       
+    end script
+
+    env SLIM_CFGFILE=${"abc"}
+    env SLIM_THEMESDIR=${"def"}
+    env FONTCONFIG_FILE=/etc/fonts/fonts.conf  				# !!! cleanup
+    env XKB_BINDIR=${"foo"}/bin         				# Needed for the Xkb extension.
+    env LD_LIBRARY_PATH=${"libX11"}/lib:${"libXext"}/lib:/usr/lib/          # related to xorg-sys-opengl - needed to load libglx for (AI)GLX support (for compiz)
+
+    ${if true
+      then "env XORG_DRI_DRIVER_PATH=${"nvidiaDrivers"}/X11R6/lib/modules/drivers/"
+    else if true
+      then "env XORG_DRI_DRIVER_PATH=${"mesa"}/lib/modules/dri"
+      else ""
+    } 
+
+    exec ${"slim"}/bin/slim
+  '';
+
+  s14 = ''
+    Escaping of ' followed by ': '''
+    Escaping of $ followed by {: ''${
+    And finally to interpret \n etc. as in a string: ''\n, ''\r, ''\t.
+  '';
+
+  # Regression test: antiquotation in '${x}' should work, but didn't.
+  s15 = let x = "bla"; in ''
+    foo
+    '${x}'
+    bar
+  '';
+
+  # Regression test: accept $'.
+  s16 = ''
+    cut -d $'\t' -f 1
+  '';
+
+  # Accept dollars at end of strings 
+  s17 = ''ending dollar $'' + ''$'' + "\n";
+
+in s1 + s2 + s3 + s4 + s5 + s6 + s7 + s8 + s9 + s10 + s11 + s12 + s13 + s14 + s15 + s16 + s17
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-let.exp b/tvix/eval/src/tests/nix_tests/eval-okay-let.exp
new file mode 100644
index 0000000000..14e24d4190
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-let.exp
@@ -0,0 +1 @@
+"foobar"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-let.nix b/tvix/eval/src/tests/nix_tests/eval-okay-let.nix
new file mode 100644
index 0000000000..fe118c5282
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-let.nix
@@ -0,0 +1,5 @@
+let {
+  x = "foo";
+  y = "bar";
+  body = x + y;
+}
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-list.exp b/tvix/eval/src/tests/nix_tests/eval-okay-list.exp
new file mode 100644
index 0000000000..f784f26d83
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-list.exp
@@ -0,0 +1 @@
+"foobarblatest"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-list.nix b/tvix/eval/src/tests/nix_tests/eval-okay-list.nix
new file mode 100644
index 0000000000..d433bcf908
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-list.nix
@@ -0,0 +1,7 @@
+with import ./lib.nix;
+
+let {
+
+  body = concat ["foo" "bar" "bla" "test"];
+    
+}
\ No newline at end of file
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-listtoattrs.exp b/tvix/eval/src/tests/nix_tests/eval-okay-listtoattrs.exp
new file mode 100644
index 0000000000..74abef7bc6
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-listtoattrs.exp
@@ -0,0 +1 @@
+"AAbar"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-listtoattrs.nix b/tvix/eval/src/tests/nix_tests/eval-okay-listtoattrs.nix
new file mode 100644
index 0000000000..4186e029b5
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-listtoattrs.nix
@@ -0,0 +1,11 @@
+# this test shows how to use listToAttrs and that evaluation is still lazy (throw isn't called)
+with import ./lib.nix;
+
+let 
+  asi = name: value : { inherit name value; };
+  list = [ ( asi "a" "A" ) ( asi "b" "B" ) ];
+  a = builtins.listToAttrs list;
+  b = builtins.listToAttrs ( list ++ list );
+  r = builtins.listToAttrs [ (asi "result" [ a b ]) ( asi "throw" (throw "this should not be thrown")) ];
+  x = builtins.listToAttrs [ (asi "foo" "bar") (asi "foo" "bla") ];
+in concat (map (x: x.a) r.result) + x.foo
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-logic.exp b/tvix/eval/src/tests/nix_tests/eval-okay-logic.exp
new file mode 100644
index 0000000000..d00491fd7e
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-logic.exp
@@ -0,0 +1 @@
+1
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-logic.nix b/tvix/eval/src/tests/nix_tests/eval-okay-logic.nix
new file mode 100644
index 0000000000..fbb1279440
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-logic.nix
@@ -0,0 +1 @@
+assert !false && (true || false) -> true; 1
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-map.exp b/tvix/eval/src/tests/nix_tests/eval-okay-map.exp
new file mode 100644
index 0000000000..dbb64f717b
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-map.exp
@@ -0,0 +1 @@
+"foobarblabarxyzzybar"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-map.nix b/tvix/eval/src/tests/nix_tests/eval-okay-map.nix
new file mode 100644
index 0000000000..a76c1d8114
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-map.nix
@@ -0,0 +1,3 @@
+with import ./lib.nix;
+
+concat (map (x: x + "bar") [ "foo" "bla" "xyzzy" ])
\ No newline at end of file
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-mapattrs.exp b/tvix/eval/src/tests/nix_tests/eval-okay-mapattrs.exp
new file mode 100644
index 0000000000..3f113f17ba
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-mapattrs.exp
@@ -0,0 +1 @@
+{ x = "x-foo"; y = "y-bar"; }
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-mapattrs.nix b/tvix/eval/src/tests/nix_tests/eval-okay-mapattrs.nix
new file mode 100644
index 0000000000..f075b6275e
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-mapattrs.nix
@@ -0,0 +1,3 @@
+with import ./lib.nix;
+
+builtins.mapAttrs (name: value: name + "-" + value) { x = "foo"; y = "bar"; }
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-nested-with.exp b/tvix/eval/src/tests/nix_tests/eval-okay-nested-with.exp
new file mode 100644
index 0000000000..0cfbf08886
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-nested-with.exp
@@ -0,0 +1 @@
+2
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-nested-with.nix b/tvix/eval/src/tests/nix_tests/eval-okay-nested-with.nix
new file mode 100644
index 0000000000..ba9d79aa79
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-nested-with.nix
@@ -0,0 +1,3 @@
+with { x = 1; };
+with { x = 2; };
+x
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-new-let.exp b/tvix/eval/src/tests/nix_tests/eval-okay-new-let.exp
new file mode 100644
index 0000000000..f98b388071
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-new-let.exp
@@ -0,0 +1 @@
+"xyzzyfoobar"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-new-let.nix b/tvix/eval/src/tests/nix_tests/eval-okay-new-let.nix
new file mode 100644
index 0000000000..7381231415
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-new-let.nix
@@ -0,0 +1,14 @@
+let
+
+  f = z: 
+
+    let
+      x = "foo";
+      y = "bar";
+      body = 1; # compat test
+    in
+      z + x + y;
+
+  arg = "xyzzy";
+
+in f arg
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-null-dynamic-attrs.exp b/tvix/eval/src/tests/nix_tests/eval-okay-null-dynamic-attrs.exp
new file mode 100644
index 0000000000..27ba77ddaf
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-null-dynamic-attrs.exp
@@ -0,0 +1 @@
+true
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-null-dynamic-attrs.nix b/tvix/eval/src/tests/nix_tests/eval-okay-null-dynamic-attrs.nix
new file mode 100644
index 0000000000..b060c0bc98
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-null-dynamic-attrs.nix
@@ -0,0 +1 @@
+{ ${null} = true; } == {}
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-overrides.exp b/tvix/eval/src/tests/nix_tests/eval-okay-overrides.exp
new file mode 100644
index 0000000000..0cfbf08886
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-overrides.exp
@@ -0,0 +1 @@
+2
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-overrides.nix b/tvix/eval/src/tests/nix_tests/eval-okay-overrides.nix
new file mode 100644
index 0000000000..358742b36e
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-overrides.nix
@@ -0,0 +1,9 @@
+let
+
+  overrides = { a = 2; };
+
+in (rec {
+  __overrides = overrides;
+  x = a;
+  a = 1;
+}).x
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-partition.exp b/tvix/eval/src/tests/nix_tests/eval-okay-partition.exp
new file mode 100644
index 0000000000..cd8b8b020c
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-partition.exp
@@ -0,0 +1 @@
+{ right = [ 0 2 4 6 8 10 100 102 104 106 108 110 ]; wrong = [ 1 3 5 7 9 101 103 105 107 109 ]; }
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-partition.nix b/tvix/eval/src/tests/nix_tests/eval-okay-partition.nix
new file mode 100644
index 0000000000..846d2ce494
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-partition.nix
@@ -0,0 +1,5 @@
+with import ./lib.nix;
+
+builtins.partition
+  (x: x / 2 * 2 == x)
+  (builtins.concatLists [ (range 0 10) (range 100 110) ])
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-path.nix b/tvix/eval/src/tests/nix_tests/eval-okay-path.nix
new file mode 100644
index 0000000000..e67168cf3e
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-path.nix
@@ -0,0 +1,7 @@
+builtins.path
+  { path = ./.;
+    filter = path: _: baseNameOf path == "data";
+    recursive = true;
+    sha256 = "1yhm3gwvg5a41yylymgblsclk95fs6jy72w0wv925mmidlhcq4sw";
+    name = "output";
+  }
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-pathexists.exp b/tvix/eval/src/tests/nix_tests/eval-okay-pathexists.exp
new file mode 100644
index 0000000000..27ba77ddaf
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-pathexists.exp
@@ -0,0 +1 @@
+true
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-pathexists.nix b/tvix/eval/src/tests/nix_tests/eval-okay-pathexists.nix
new file mode 100644
index 0000000000..50c28ee0cd
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-pathexists.nix
@@ -0,0 +1,5 @@
+builtins.pathExists (builtins.toPath ./lib.nix)
+&& builtins.pathExists (builtins.toPath (builtins.toString ./lib.nix))
+&& !builtins.pathExists (builtins.toPath (builtins.toString ./bla.nix))
+&& builtins.pathExists ./lib.nix
+&& !builtins.pathExists ./bla.nix
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-patterns.exp b/tvix/eval/src/tests/nix_tests/eval-okay-patterns.exp
new file mode 100644
index 0000000000..a4304010fe
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-patterns.exp
@@ -0,0 +1 @@
+"abcxyzDDDDEFijk"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-patterns.nix b/tvix/eval/src/tests/nix_tests/eval-okay-patterns.nix
new file mode 100644
index 0000000000..96fd25a015
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-patterns.nix
@@ -0,0 +1,16 @@
+let
+
+  f = args@{x, y, z}: x + args.y + z;
+
+  g = {x, y, z}@args: f args;
+
+  h = {x ? "d", y ? x, z ? args.x}@args: x + y + z;
+
+  j = {x, y, z, ...}: x + y + z;
+
+in
+  f {x = "a"; y = "b"; z = "c";} +
+  g {x = "x"; y = "y"; z = "z";} +
+  h {x = "D";} +
+  h {x = "D"; y = "E"; z = "F";} +
+  j {x = "i"; y = "j"; z = "k"; bla = "bla"; foo = "bar";}
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-readDir.exp b/tvix/eval/src/tests/nix_tests/eval-okay-readDir.exp
new file mode 100644
index 0000000000..bf8d2c14ea
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-readDir.exp
@@ -0,0 +1 @@
+{ bar = "regular"; foo = "directory"; }
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-readDir.nix b/tvix/eval/src/tests/nix_tests/eval-okay-readDir.nix
new file mode 100644
index 0000000000..a7ec9292aa
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-readDir.nix
@@ -0,0 +1 @@
+builtins.readDir ./readDir
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-readfile.exp b/tvix/eval/src/tests/nix_tests/eval-okay-readfile.exp
new file mode 100644
index 0000000000..a2c87d0c43
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-readfile.exp
@@ -0,0 +1 @@
+"builtins.readFile ./eval-okay-readfile.nix\n"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-readfile.nix b/tvix/eval/src/tests/nix_tests/eval-okay-readfile.nix
new file mode 100644
index 0000000000..82f7cb1743
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-readfile.nix
@@ -0,0 +1 @@
+builtins.readFile ./eval-okay-readfile.nix
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-redefine-builtin.exp b/tvix/eval/src/tests/nix_tests/eval-okay-redefine-builtin.exp
new file mode 100644
index 0000000000..c508d5366f
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-redefine-builtin.exp
@@ -0,0 +1 @@
+false
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-redefine-builtin.nix b/tvix/eval/src/tests/nix_tests/eval-okay-redefine-builtin.nix
new file mode 100644
index 0000000000..df9fc3f37d
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-redefine-builtin.nix
@@ -0,0 +1,3 @@
+let
+  throw = abort "Error!";
+in (builtins.tryEval <foobaz>).success
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-regex-match.exp b/tvix/eval/src/tests/nix_tests/eval-okay-regex-match.exp
new file mode 100644
index 0000000000..27ba77ddaf
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-regex-match.exp
@@ -0,0 +1 @@
+true
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-regex-match.nix b/tvix/eval/src/tests/nix_tests/eval-okay-regex-match.nix
new file mode 100644
index 0000000000..273e259071
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-regex-match.nix
@@ -0,0 +1,29 @@
+with builtins;
+
+let
+
+  matches = pat: s: match pat s != null;
+
+  splitFN = match "((.*)/)?([^/]*)\\.(nix|cc)";
+
+in
+
+assert  matches "foobar" "foobar";
+assert  matches "fo*" "f";
+assert !matches "fo+" "f";
+assert  matches "fo*" "fo";
+assert  matches "fo*" "foo";
+assert  matches "fo+" "foo";
+assert  matches "fo{1,2}" "foo";
+assert !matches "fo{1,2}" "fooo";
+assert !matches "fo*" "foobar";
+assert  matches "[[:space:]]+([^[:space:]]+)[[:space:]]+" "  foo   ";
+assert !matches "[[:space:]]+([[:upper:]]+)[[:space:]]+" "  foo   ";
+
+assert match "(.*)\\.nix" "foobar.nix" == [ "foobar" ];
+assert match "[[:space:]]+([[:upper:]]+)[[:space:]]+" "  FOO   " == [ "FOO" ];
+
+assert splitFN "/path/to/foobar.nix" == [ "/path/to/" "/path/to" "foobar" "nix" ];
+assert splitFN "foobar.cc" == [ null null "foobar" "cc" ];
+
+true
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-regex-split.exp b/tvix/eval/src/tests/nix_tests/eval-okay-regex-split.exp
new file mode 100644
index 0000000000..27ba77ddaf
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-regex-split.exp
@@ -0,0 +1 @@
+true
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-regex-split.nix b/tvix/eval/src/tests/nix_tests/eval-okay-regex-split.nix
new file mode 100644
index 0000000000..0073e05778
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-regex-split.nix
@@ -0,0 +1,48 @@
+with builtins;
+
+# Non capturing regex returns empty lists
+assert  split "foobar" "foobar"  == ["" [] ""];
+assert  split "fo*" "f"          == ["" [] ""];
+assert  split "fo+" "f"          == ["f"];
+assert  split "fo*" "fo"         == ["" [] ""];
+assert  split "fo*" "foo"        == ["" [] ""];
+assert  split "fo+" "foo"        == ["" [] ""];
+assert  split "fo{1,2}" "foo"    == ["" [] ""];
+assert  split "fo{1,2}" "fooo"   == ["" [] "o"];
+assert  split "fo*" "foobar"     == ["" [] "bar"];
+
+# Capturing regex returns a list of sub-matches
+assert  split "(fo*)" "f"        == ["" ["f"] ""];
+assert  split "(fo+)" "f"        == ["f"];
+assert  split "(fo*)" "fo"       == ["" ["fo"] ""];
+assert  split "(f)(o*)" "f"      == ["" ["f" ""] ""];
+assert  split "(f)(o*)" "foo"    == ["" ["f" "oo"] ""];
+assert  split "(fo+)" "foo"      == ["" ["foo"] ""];
+assert  split "(fo{1,2})" "foo"  == ["" ["foo"] ""];
+assert  split "(fo{1,2})" "fooo" == ["" ["foo"] "o"];
+assert  split "(fo*)" "foobar"   == ["" ["foo"] "bar"];
+
+# Matches are greedy.
+assert  split "(o+)" "oooofoooo" == ["" ["oooo"] "f" ["oooo"] ""];
+
+# Matches multiple times.
+assert  split "(b)" "foobarbaz"  == ["foo" ["b"] "ar" ["b"] "az"];
+
+# Split large strings containing newlines. null are inserted when a
+# pattern within the current did not match anything.
+assert  split "[[:space:]]+|([',.!?])" ''
+  Nix Rocks!
+  That's why I use it.
+''  == [
+  "Nix" [ null ] "Rocks" ["!"] "" [ null ]
+  "That" ["'"] "s" [ null ] "why" [ null ] "I" [ null ] "use" [ null ] "it" ["."] "" [ null ]
+  ""
+];
+
+# Documentation examples
+assert  split  "(a)b" "abc"      == [ "" [ "a" ] "c" ];
+assert  split  "([ac])" "abc"    == [ "" [ "a" ] "b" [ "c" ] "" ];
+assert  split  "(a)|(c)" "abc"   == [ "" [ "a" null ] "b" [ null "c" ] "" ];
+assert  split  "([[:upper:]]+)" "  FOO   " == [ "  " [ "FOO" ] "   " ];
+
+true
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-remove.exp b/tvix/eval/src/tests/nix_tests/eval-okay-remove.exp
new file mode 100644
index 0000000000..8d38505c16
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-remove.exp
@@ -0,0 +1 @@
+456
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-remove.nix b/tvix/eval/src/tests/nix_tests/eval-okay-remove.nix
new file mode 100644
index 0000000000..4ad5ba897f
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-remove.nix
@@ -0,0 +1,5 @@
+let {
+  attrs = {x = 123; y = 456;};
+
+  body = (removeAttrs attrs ["x"]).y;
+}
\ No newline at end of file
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-replacestrings.exp b/tvix/eval/src/tests/nix_tests/eval-okay-replacestrings.exp
new file mode 100644
index 0000000000..72e8274d8c
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-replacestrings.exp
@@ -0,0 +1 @@
+[ "faabar" "fbar" "fubar" "faboor" "fubar" "XaXbXcX" "X" "a_b" ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-replacestrings.nix b/tvix/eval/src/tests/nix_tests/eval-okay-replacestrings.nix
new file mode 100644
index 0000000000..bd8031fc00
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-replacestrings.nix
@@ -0,0 +1,11 @@
+with builtins;
+
+[ (replaceStrings ["o"] ["a"] "foobar")
+  (replaceStrings ["o"] [""] "foobar")
+  (replaceStrings ["oo"] ["u"] "foobar")
+  (replaceStrings ["oo" "a"] ["a" "oo"] "foobar")
+  (replaceStrings ["oo" "oo"] ["u" "i"] "foobar")
+  (replaceStrings [""] ["X"] "abc")
+  (replaceStrings [""] ["X"] "")
+  (replaceStrings ["-"] ["_"] "a-b")
+]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-scope-1.exp b/tvix/eval/src/tests/nix_tests/eval-okay-scope-1.exp
new file mode 100644
index 0000000000..00750edc07
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-scope-1.exp
@@ -0,0 +1 @@
+3
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-scope-1.nix b/tvix/eval/src/tests/nix_tests/eval-okay-scope-1.nix
new file mode 100644
index 0000000000..fa38a7174e
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-scope-1.nix
@@ -0,0 +1,6 @@
+(({x}: x:
+
+  { x = 1;
+    y = x;
+  }
+) {x = 2;} 3).y
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-scope-2.exp b/tvix/eval/src/tests/nix_tests/eval-okay-scope-2.exp
new file mode 100644
index 0000000000..d00491fd7e
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-scope-2.exp
@@ -0,0 +1 @@
+1
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-scope-2.nix b/tvix/eval/src/tests/nix_tests/eval-okay-scope-2.nix
new file mode 100644
index 0000000000..eb8b02bc49
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-scope-2.nix
@@ -0,0 +1,6 @@
+((x: {x}:
+  rec {
+    x = 1;
+    y = x;
+  }
+) 2 {x = 3;}).y
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-scope-3.exp b/tvix/eval/src/tests/nix_tests/eval-okay-scope-3.exp
new file mode 100644
index 0000000000..b8626c4cff
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-scope-3.exp
@@ -0,0 +1 @@
+4
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-scope-3.nix b/tvix/eval/src/tests/nix_tests/eval-okay-scope-3.nix
new file mode 100644
index 0000000000..10d6bc04d8
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-scope-3.nix
@@ -0,0 +1,6 @@
+((x: as: {x}:
+  rec {
+    inherit (as) x;
+    y = x;
+  }
+) 2 {x = 4;} {x = 3;}).y
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-scope-4.exp b/tvix/eval/src/tests/nix_tests/eval-okay-scope-4.exp
new file mode 100644
index 0000000000..00ff03a46c
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-scope-4.exp
@@ -0,0 +1 @@
+"ccdd"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-scope-4.nix b/tvix/eval/src/tests/nix_tests/eval-okay-scope-4.nix
new file mode 100644
index 0000000000..dc8243bc85
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-scope-4.nix
@@ -0,0 +1,10 @@
+let {
+
+  x = "a";
+  y = "b";
+
+  f = {x ? y, y ? x}: x + y;
+
+  body = f {x = "c";} + f {y = "d";};
+
+}
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-scope-6.exp b/tvix/eval/src/tests/nix_tests/eval-okay-scope-6.exp
new file mode 100644
index 0000000000..00ff03a46c
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-scope-6.exp
@@ -0,0 +1 @@
+"ccdd"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-scope-6.nix b/tvix/eval/src/tests/nix_tests/eval-okay-scope-6.nix
new file mode 100644
index 0000000000..0995d4e7e7
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-scope-6.nix
@@ -0,0 +1,7 @@
+let {
+
+  f = {x ? y, y ? x}: x + y;
+
+  body = f {x = "c";} + f {y = "d";};
+
+}
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-scope-7.exp b/tvix/eval/src/tests/nix_tests/eval-okay-scope-7.exp
new file mode 100644
index 0000000000..d00491fd7e
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-scope-7.exp
@@ -0,0 +1 @@
+1
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-scope-7.nix b/tvix/eval/src/tests/nix_tests/eval-okay-scope-7.nix
new file mode 100644
index 0000000000..4da02968f6
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-scope-7.nix
@@ -0,0 +1,6 @@
+rec {
+  inherit (x) y;
+  x = {
+    y = 1;
+  };
+}.y
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-search-path.exp b/tvix/eval/src/tests/nix_tests/eval-okay-search-path.exp
new file mode 100644
index 0000000000..4519bc406d
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-search-path.exp
@@ -0,0 +1 @@
+"abccX"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-search-path.flags b/tvix/eval/src/tests/nix_tests/eval-okay-search-path.flags
new file mode 100644
index 0000000000..a28e682100
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-search-path.flags
@@ -0,0 +1 @@
+-I lang/dir1 -I lang/dir2 -I dir5=lang/dir3
\ No newline at end of file
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-search-path.nix b/tvix/eval/src/tests/nix_tests/eval-okay-search-path.nix
new file mode 100644
index 0000000000..cca41f821f
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-search-path.nix
@@ -0,0 +1,11 @@
+with import ./lib.nix;
+with builtins;
+
+assert pathExists <nix/buildenv.nix>;
+
+assert length __nixPath == 6;
+assert length (filter (x: x.prefix == "nix") __nixPath) == 1;
+assert length (filter (x: baseNameOf x.path == "dir4") __nixPath) == 1;
+
+import <a.nix> + import <b.nix> + import <c.nix> + import <dir5/c.nix>
+  + (let __nixPath = [ { path = ./dir2; } { path = ./dir1; } ]; in import <a.nix>)
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-seq.exp b/tvix/eval/src/tests/nix_tests/eval-okay-seq.exp
new file mode 100644
index 0000000000..0cfbf08886
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-seq.exp
@@ -0,0 +1 @@
+2
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-seq.nix b/tvix/eval/src/tests/nix_tests/eval-okay-seq.nix
new file mode 100644
index 0000000000..0a9a21c03b
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-seq.nix
@@ -0,0 +1 @@
+builtins.seq 1 2
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-sort.exp b/tvix/eval/src/tests/nix_tests/eval-okay-sort.exp
new file mode 100644
index 0000000000..148b935163
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-sort.exp
@@ -0,0 +1 @@
+[ [ 42 77 147 249 483 526 ] [ 526 483 249 147 77 42 ] [ "bar" "fnord" "foo" "xyzzy" ] [ { key = 1; value = "foo"; } { key = 1; value = "fnord"; } { key = 2; value = "bar"; } ] ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-sort.nix b/tvix/eval/src/tests/nix_tests/eval-okay-sort.nix
new file mode 100644
index 0000000000..8299c3a4a3
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-sort.nix
@@ -0,0 +1,8 @@
+with builtins;
+
+[ (sort lessThan [ 483 249 526 147 42 77 ])
+  (sort (x: y: y < x) [ 483 249 526 147 42 77 ])
+  (sort lessThan [ "foo" "bar" "xyzzy" "fnord" ])
+  (sort (x: y: x.key < y.key)
+    [ { key = 1; value = "foo"; } { key = 2; value = "bar"; } { key = 1; value = "fnord"; } ]) 
+]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-splitversion.exp b/tvix/eval/src/tests/nix_tests/eval-okay-splitversion.exp
new file mode 100644
index 0000000000..153ceb8186
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-splitversion.exp
@@ -0,0 +1 @@
+[ "1" "2" "3" ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-splitversion.nix b/tvix/eval/src/tests/nix_tests/eval-okay-splitversion.nix
new file mode 100644
index 0000000000..9e5c99d2e7
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-splitversion.nix
@@ -0,0 +1 @@
+builtins.splitVersion "1.2.3"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-string.exp b/tvix/eval/src/tests/nix_tests/eval-okay-string.exp
new file mode 100644
index 0000000000..63f650f73a
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-string.exp
@@ -0,0 +1 @@
+"foobar/a/b/c/d/foo/xyzzy/foo.txt/../foo/x/yescape: \"quote\" \n \\end\nof\nlinefoobarblaatfoo$bar$\"$\"$"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-string.nix b/tvix/eval/src/tests/nix_tests/eval-okay-string.nix
new file mode 100644
index 0000000000..47cc989ad4
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-string.nix
@@ -0,0 +1,12 @@
+"foo" + "bar"
+  + toString (/a/b + /c/d)
+  + toString (/foo/bar + "/../xyzzy/." + "/foo.txt")
+  + ("/../foo" + toString /x/y)
+  + "escape: \"quote\" \n \\"
+  + "end
+of
+line"
+  + "foo${if true then "b${"a" + "r"}" else "xyzzy"}blaat"
+  + "foo$bar"
+  + "$\"$\""
+  + "$"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-strings-as-attrs-names.exp b/tvix/eval/src/tests/nix_tests/eval-okay-strings-as-attrs-names.exp
new file mode 100644
index 0000000000..27ba77ddaf
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-strings-as-attrs-names.exp
@@ -0,0 +1 @@
+true
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-strings-as-attrs-names.nix b/tvix/eval/src/tests/nix_tests/eval-okay-strings-as-attrs-names.nix
new file mode 100644
index 0000000000..5e40928dbe
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-strings-as-attrs-names.nix
@@ -0,0 +1,20 @@
+let
+
+  attr = {
+    "key 1" = "test";
+    "key 2" = "caseok";
+  };
+
+  t1 = builtins.getAttr "key 1" attr;
+  t2 = attr."key 2";
+  t3 = attr ? "key 1";
+  t4 = builtins.attrNames { inherit (attr) "key 1"; };
+
+  # This is permitted, but there is currently no way to reference this
+  # variable.
+  "foo bar" = 1;
+
+in t1 == "test"
+   && t2 == "caseok"
+   && t3 == true
+   && t4 == ["key 1"]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-substring.exp b/tvix/eval/src/tests/nix_tests/eval-okay-substring.exp
new file mode 100644
index 0000000000..6aace04b0f
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-substring.exp
@@ -0,0 +1 @@
+"ooxfoobarybarzobaabbc"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-substring.nix b/tvix/eval/src/tests/nix_tests/eval-okay-substring.nix
new file mode 100644
index 0000000000..424af00d9b
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-substring.nix
@@ -0,0 +1,21 @@
+with builtins;
+
+let
+
+  s = "foobar";
+
+in
+
+substring 1 2 s
++ "x"
++ substring 0 (stringLength s) s
++ "y"
++ substring 3 100 s
++ "z"
++ substring 2 (sub (stringLength s) 3) s
++ "a"
++ substring 3 0 s
++ "b"
++ substring 3 1 s
++ "c"
++ substring 5 10 "perl"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-tail-call-1.exp-disabled b/tvix/eval/src/tests/nix_tests/eval-okay-tail-call-1.exp-disabled
new file mode 100644
index 0000000000..f7393e847d
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-tail-call-1.exp-disabled
@@ -0,0 +1 @@
+100000
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-tail-call-1.nix b/tvix/eval/src/tests/nix_tests/eval-okay-tail-call-1.nix
new file mode 100644
index 0000000000..a3962ce3fd
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-tail-call-1.nix
@@ -0,0 +1,3 @@
+let
+  f = n: if n == 100000 then n else f (n + 1);
+in f 0
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-tojson.exp b/tvix/eval/src/tests/nix_tests/eval-okay-tojson.exp
new file mode 100644
index 0000000000..e92aae3235
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-tojson.exp
@@ -0,0 +1 @@
+"{\"a\":123,\"b\":-456,\"c\":\"foo\",\"d\":\"foo\\n\\\"bar\\\"\",\"e\":true,\"f\":false,\"g\":[1,2,3],\"h\":[\"a\",[\"b\",{\"foo\\nbar\":{}}]],\"i\":3,\"j\":1.44,\"k\":\"foo\"}"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-tojson.nix b/tvix/eval/src/tests/nix_tests/eval-okay-tojson.nix
new file mode 100644
index 0000000000..ce67943bea
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-tojson.nix
@@ -0,0 +1,13 @@
+builtins.toJSON
+  { a = 123;
+    b = -456;
+    c = "foo";
+    d = "foo\n\"bar\"";
+    e = true;
+    f = false;
+    g = [ 1 2 3 ];
+    h = [ "a" [ "b" { "foo\nbar" = {}; } ] ];
+    i = 1 + 2;
+    j = 1.44;
+    k = { __toString = self: self.a; a = "foo"; };
+  }
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-toxml.exp b/tvix/eval/src/tests/nix_tests/eval-okay-toxml.exp
new file mode 100644
index 0000000000..828220890e
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-toxml.exp
@@ -0,0 +1 @@
+"<?xml version='1.0' encoding='utf-8'?>\n<expr>\n  <attrs>\n    <attr name=\"a\">\n      <string value=\"s\" />\n    </attr>\n  </attrs>\n</expr>\n"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-toxml.nix b/tvix/eval/src/tests/nix_tests/eval-okay-toxml.nix
new file mode 100644
index 0000000000..068c97a6c1
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-toxml.nix
@@ -0,0 +1,3 @@
+# Make sure the expected XML output is produced; in particular, make sure it
+# doesn't contain source location information.
+builtins.toXML { a = "s"; }
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-toxml2.exp b/tvix/eval/src/tests/nix_tests/eval-okay-toxml2.exp
new file mode 100644
index 0000000000..634a841eb1
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-toxml2.exp
@@ -0,0 +1 @@
+"<?xml version='1.0' encoding='utf-8'?>\n<expr>\n  <list>\n    <string value=\"ab\" />\n    <int value=\"10\" />\n    <attrs>\n      <attr name=\"x\">\n        <string value=\"x\" />\n      </attr>\n      <attr name=\"y\">\n        <string value=\"x\" />\n      </attr>\n    </attrs>\n  </list>\n</expr>\n"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-toxml2.nix b/tvix/eval/src/tests/nix_tests/eval-okay-toxml2.nix
new file mode 100644
index 0000000000..ff1791b30e
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-toxml2.nix
@@ -0,0 +1 @@
+builtins.toXML [("a" + "b") 10 (rec {x = "x"; y = x;})]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-tryeval.exp b/tvix/eval/src/tests/nix_tests/eval-okay-tryeval.exp
new file mode 100644
index 0000000000..2b2e6fa711
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-tryeval.exp
@@ -0,0 +1 @@
+{ x = { success = true; value = "x"; }; y = { success = false; value = false; }; z = { success = false; value = false; }; }
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-tryeval.nix b/tvix/eval/src/tests/nix_tests/eval-okay-tryeval.nix
new file mode 100644
index 0000000000..629bc440a8
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-tryeval.nix
@@ -0,0 +1,5 @@
+{
+  x = builtins.tryEval "x";
+  y = builtins.tryEval (assert false; "y");
+  z = builtins.tryEval (throw "bla");
+}
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-types.exp b/tvix/eval/src/tests/nix_tests/eval-okay-types.exp
new file mode 100644
index 0000000000..92a1532993
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-types.exp
@@ -0,0 +1 @@
+[ true false true false true false true false true true true true true true true true true true true false true true true false "int" "bool" "string" "null" "set" "list" "lambda" "lambda" "lambda" "lambda" ]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-types.nix b/tvix/eval/src/tests/nix_tests/eval-okay-types.nix
new file mode 100644
index 0000000000..9b58be5d1d
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-types.nix
@@ -0,0 +1,37 @@
+with builtins;
+
+[ (isNull null)
+  (isNull (x: x))
+  (isFunction (x: x))
+  (isFunction "fnord")
+  (isString ("foo" + "bar"))
+  (isString [ "x" ])
+  (isInt (1 + 2))
+  (isInt { x = 123; })
+  (isInt (1 / 2))
+  (isInt (1 + 1))
+  (isInt (1 / 2))
+  (isInt (1 * 2))
+  (isInt (1 - 2))
+  (isFloat (1.2))
+  (isFloat (1 + 1.0))
+  (isFloat (1 / 2.0))
+  (isFloat (1 * 2.0))
+  (isFloat (1 - 2.0))
+  (isBool (true && false))
+  (isBool null)
+  (isPath /nix/store)
+  (isPath ./.)
+  (isAttrs { x = 123; })
+  (isAttrs null)
+  (typeOf (3 * 4))
+  (typeOf true)
+  (typeOf "xyzzy")
+  (typeOf null)
+  (typeOf { x = 456; })
+  (typeOf [ 1 2 3 ])
+  (typeOf (x: x))
+  (typeOf ((x: y: x) 1))
+  (typeOf map)
+  (typeOf (map (x: x)))
+]
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-versions.exp b/tvix/eval/src/tests/nix_tests/eval-okay-versions.exp
new file mode 100644
index 0000000000..27ba77ddaf
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-versions.exp
@@ -0,0 +1 @@
+true
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-versions.nix b/tvix/eval/src/tests/nix_tests/eval-okay-versions.nix
new file mode 100644
index 0000000000..e63c36586b
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-versions.nix
@@ -0,0 +1,40 @@
+let
+
+  name1 = "hello-1.0.2";
+  name2 = "hello";
+  name3 = "915resolution-0.5.2";
+  name4 = "xf86-video-i810-1.7.4";
+
+  eq = 0;
+  lt = builtins.sub 0 1;
+  gt = 1;
+
+  versionTest = v1: v2: expected:
+    let d1 = builtins.compareVersions v1 v2;
+        d2 = builtins.compareVersions v2 v1;
+    in d1 == builtins.sub 0 d2 && d1 == expected;
+
+  tests = [
+    ((builtins.parseDrvName name1).name == "hello")
+    ((builtins.parseDrvName name1).version == "1.0.2")
+    ((builtins.parseDrvName name2).name == "hello")
+    ((builtins.parseDrvName name2).version == "")
+    ((builtins.parseDrvName name3).name == "915resolution")
+    ((builtins.parseDrvName name3).version == "0.5.2")
+    ((builtins.parseDrvName name4).name == "xf86-video-i810")
+    ((builtins.parseDrvName name4).version == "1.7.4")
+    (versionTest "1.0" "2.3" lt)
+    (versionTest "2.1" "2.3" lt)
+    (versionTest "2.3" "2.3" eq)
+    (versionTest "2.5" "2.3" gt)
+    (versionTest "3.1" "2.3" gt)
+    (versionTest "2.3.1" "2.3" gt)
+    (versionTest "2.3.1" "2.3a" gt)
+    (versionTest "2.3pre1" "2.3" lt)
+    (versionTest "2.3pre3" "2.3pre12" lt)
+    (versionTest "2.3a" "2.3c" lt)
+    (versionTest "2.3pre1" "2.3c" lt)
+    (versionTest "2.3pre1" "2.3q" lt)
+  ];
+
+in (import ./lib.nix).and tests
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-with.exp b/tvix/eval/src/tests/nix_tests/eval-okay-with.exp
new file mode 100644
index 0000000000..378c8dc804
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-with.exp
@@ -0,0 +1 @@
+"xyzzybarxyzzybar"
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-with.nix b/tvix/eval/src/tests/nix_tests/eval-okay-with.nix
new file mode 100644
index 0000000000..033e8d3aba
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-with.nix
@@ -0,0 +1,19 @@
+let {
+
+  a = "xyzzy";
+
+  as = {
+    a = "foo";
+    b = "bar";
+  };
+
+  bs = {
+    a = "bar";
+  };
+
+  x = with as; a + b;
+
+  y = with as; with bs; a + b;
+
+  body = x + y;
+}
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-xml.exp.xml b/tvix/eval/src/tests/nix_tests/eval-okay-xml.exp.xml
new file mode 100644
index 0000000000..92b75e0b8b
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-xml.exp.xml
@@ -0,0 +1,52 @@
+<?xml version='1.0' encoding='utf-8'?>
+<expr>
+  <attrs>
+    <attr name="a">
+      <string value="foo" />
+    </attr>
+    <attr name="at">
+      <function>
+        <attrspat name="args">
+          <attr name="x" />
+          <attr name="y" />
+          <attr name="z" />
+        </attrspat>
+      </function>
+    </attr>
+    <attr name="b">
+      <string value="bar" />
+    </attr>
+    <attr name="c">
+      <string value="foobar" />
+    </attr>
+    <attr name="ellipsis">
+      <function>
+        <attrspat ellipsis="1">
+          <attr name="x" />
+          <attr name="y" />
+          <attr name="z" />
+        </attrspat>
+      </function>
+    </attr>
+    <attr name="f">
+      <function>
+        <attrspat>
+          <attr name="z" />
+          <attr name="x" />
+          <attr name="y" />
+        </attrspat>
+      </function>
+    </attr>
+    <attr name="id">
+      <function>
+        <varpat name="x" />
+      </function>
+    </attr>
+    <attr name="x">
+      <int value="123" />
+    </attr>
+    <attr name="y">
+      <float value="567.89" />
+    </attr>
+  </attrs>
+</expr>
diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-xml.nix b/tvix/eval/src/tests/nix_tests/eval-okay-xml.nix
new file mode 100644
index 0000000000..9ee9f8a0b4
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-xml.nix
@@ -0,0 +1,21 @@
+rec {
+
+  x = 123;
+
+  y = 567.890;
+
+  a = "foo";
+
+  b = "bar";
+
+  c = "foo" + "bar";
+
+  f = {z, x, y}: if y then x else z;
+
+  id = x: x;
+
+  at = args@{x, y, z}: x;
+
+  ellipsis = {x, y, z, ...}: x;
+
+}
diff --git a/tvix/eval/src/tests/nix_tests/imported.nix b/tvix/eval/src/tests/nix_tests/imported.nix
new file mode 100644
index 0000000000..fb39ee4efa
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/imported.nix
@@ -0,0 +1,3 @@
+# The function ‘range’ comes from lib.nix and was added to the lexical
+# scope by scopedImport.
+range 1 5 ++ import ./imported2.nix
diff --git a/tvix/eval/src/tests/nix_tests/imported2.nix b/tvix/eval/src/tests/nix_tests/imported2.nix
new file mode 100644
index 0000000000..6d0a2992b7
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/imported2.nix
@@ -0,0 +1 @@
+range 6 10
diff --git a/tvix/eval/src/tests/nix_tests/lib.nix b/tvix/eval/src/tests/nix_tests/lib.nix
new file mode 100644
index 0000000000..028a538314
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/lib.nix
@@ -0,0 +1,61 @@
+with builtins;
+
+rec {
+
+  fold = op: nul: list:
+    if list == []
+    then nul
+    else op (head list) (fold op nul (tail list));
+
+  concat =
+    fold (x: y: x + y) "";
+
+  and = fold (x: y: x && y) true;
+
+  flatten = x:
+    if isList x
+    then fold (x: y: (flatten x) ++ y) [] x
+    else [x];
+
+  sum = foldl' (x: y: add x y) 0;
+
+  hasSuffix = ext: fileName:
+    let lenFileName = stringLength fileName;
+        lenExt = stringLength ext;
+    in !(lessThan lenFileName lenExt) &&
+       substring (sub lenFileName lenExt) lenFileName fileName == ext;
+
+  # Split a list at the given position.
+  splitAt = pos: list:
+    if pos == 0 then {first = []; second = list;} else
+    if list == [] then {first = []; second = [];} else
+    let res = splitAt (sub pos 1) (tail list);
+    in {first = [(head list)] ++ res.first; second = res.second;};
+
+  # Stable merge sort.
+  sortBy = comp: list:
+    if lessThan 1 (length list)
+    then
+      let
+        split = splitAt (div (length list) 2) list;
+        first = sortBy comp split.first;
+        second = sortBy comp split.second;
+      in mergeLists comp first second
+    else list;
+
+  mergeLists = comp: list1: list2:
+    if list1 == [] then list2 else
+    if list2 == [] then list1 else
+    if comp (head list2) (head list1) then [(head list2)] ++ mergeLists comp list1 (tail list2) else
+    [(head list1)] ++ mergeLists comp (tail list1) list2;
+
+  id = x: x;
+
+  const = x: y: x;
+
+  range = first: last:
+    if first > last
+      then []
+      else genList (n: first + n) (last - first + 1);
+
+}
diff --git a/tvix/eval/src/tests/nix_tests/parse-fail-dup-attrs-1.nix b/tvix/eval/src/tests/nix_tests/parse-fail-dup-attrs-1.nix
new file mode 100644
index 0000000000..2c02317d2a
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-fail-dup-attrs-1.nix
@@ -0,0 +1,4 @@
+{ x = 123;
+  y = 456;
+  x = 789;
+}
diff --git a/tvix/eval/src/tests/nix_tests/parse-fail-dup-attrs-2.nix b/tvix/eval/src/tests/nix_tests/parse-fail-dup-attrs-2.nix
new file mode 100644
index 0000000000..864d9865e0
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-fail-dup-attrs-2.nix
@@ -0,0 +1,13 @@
+let {
+
+  as = {
+    x = 123;
+    y = 456;
+  };
+
+  bs = {
+    x = 789;
+    inherit (as) x;
+  };
+  
+}
diff --git a/tvix/eval/src/tests/nix_tests/parse-fail-dup-attrs-3.nix b/tvix/eval/src/tests/nix_tests/parse-fail-dup-attrs-3.nix
new file mode 100644
index 0000000000..114d19779f
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-fail-dup-attrs-3.nix
@@ -0,0 +1,13 @@
+let {
+
+  as = {
+    x = 123;
+    y = 456;
+  };
+
+  bs = rec {
+    x = 789;
+    inherit (as) x;
+  };
+  
+}
diff --git a/tvix/eval/src/tests/nix_tests/parse-fail-dup-attrs-4.nix b/tvix/eval/src/tests/nix_tests/parse-fail-dup-attrs-4.nix
new file mode 100644
index 0000000000..77417432b3
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-fail-dup-attrs-4.nix
@@ -0,0 +1,4 @@
+{
+  services.ssh.port = 22;
+  services.ssh.port = 23;
+}
diff --git a/tvix/eval/src/tests/nix_tests/parse-fail-dup-attrs-7.nix b/tvix/eval/src/tests/nix_tests/parse-fail-dup-attrs-7.nix
new file mode 100644
index 0000000000..bbc3eb08c0
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-fail-dup-attrs-7.nix
@@ -0,0 +1,9 @@
+rec {
+
+  x = 1;
+
+  as = {
+    inherit x;
+    inherit x;
+  };
+}
\ No newline at end of file
diff --git a/tvix/eval/src/tests/nix_tests/parse-fail-dup-formals.nix b/tvix/eval/src/tests/nix_tests/parse-fail-dup-formals.nix
new file mode 100644
index 0000000000..a0edd91a96
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-fail-dup-formals.nix
@@ -0,0 +1 @@
+{x, y, x}: x
\ No newline at end of file
diff --git a/tvix/eval/src/tests/nix_tests/parse-fail-mixed-nested-attrs1.nix b/tvix/eval/src/tests/nix_tests/parse-fail-mixed-nested-attrs1.nix
new file mode 100644
index 0000000000..11e40e66fd
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-fail-mixed-nested-attrs1.nix
@@ -0,0 +1,4 @@
+{ 
+  x.z = 3; 
+  x = { y = 3; z = 3; }; 
+}
diff --git a/tvix/eval/src/tests/nix_tests/parse-fail-mixed-nested-attrs2.nix b/tvix/eval/src/tests/nix_tests/parse-fail-mixed-nested-attrs2.nix
new file mode 100644
index 0000000000..17da82e5f0
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-fail-mixed-nested-attrs2.nix
@@ -0,0 +1,4 @@
+{ 
+  x.y.y = 3; 
+  x = { y.y= 3; z = 3; }; 
+}
diff --git a/tvix/eval/src/tests/nix_tests/parse-fail-patterns-1.nix b/tvix/eval/src/tests/nix_tests/parse-fail-patterns-1.nix
new file mode 100644
index 0000000000..7b40616417
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-fail-patterns-1.nix
@@ -0,0 +1 @@
+args@{args, x, y, z}: x
diff --git a/tvix/eval/src/tests/nix_tests/parse-fail-regression-20060610.nix b/tvix/eval/src/tests/nix_tests/parse-fail-regression-20060610.nix
new file mode 100644
index 0000000000..b1934f7e1e
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-fail-regression-20060610.nix
@@ -0,0 +1,11 @@
+let {
+  x =
+    {gcc}:
+    {
+      inherit gcc;
+    };
+
+  body = ({
+    inherit gcc;
+  }).gcc;
+}
diff --git a/tvix/eval/src/tests/nix_tests/parse-fail-uft8.nix b/tvix/eval/src/tests/nix_tests/parse-fail-uft8.nix
new file mode 100644
index 0000000000..34948d48ae
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-fail-uft8.nix
@@ -0,0 +1 @@
+123 é 4
diff --git a/tvix/eval/src/tests/nix_tests/parse-fail-undef-var-2.nix b/tvix/eval/src/tests/nix_tests/parse-fail-undef-var-2.nix
new file mode 100644
index 0000000000..c10a52b1ea
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-fail-undef-var-2.nix
@@ -0,0 +1,7 @@
+let {
+
+  f = {x, y : ["baz" "bar" z "bat"]}: x + y;
+
+  body = f {x = "foo"; y = "bar";};
+
+}
diff --git a/tvix/eval/src/tests/nix_tests/parse-fail-undef-var.nix b/tvix/eval/src/tests/nix_tests/parse-fail-undef-var.nix
new file mode 100644
index 0000000000..7b63008110
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-fail-undef-var.nix
@@ -0,0 +1 @@
+x: y
diff --git a/tvix/eval/src/tests/nix_tests/parse-okay-1.nix b/tvix/eval/src/tests/nix_tests/parse-okay-1.nix
new file mode 100644
index 0000000000..23a58ed109
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-okay-1.nix
@@ -0,0 +1 @@
+{x, y, z}: x + y + z
diff --git a/tvix/eval/src/tests/nix_tests/parse-okay-crlf.nix b/tvix/eval/src/tests/nix_tests/parse-okay-crlf.nix
new file mode 100644
index 0000000000..21518d4c6d
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-okay-crlf.nix
@@ -0,0 +1,17 @@
+rec {
+
+  /* Dit is

+  een test. */
+
+  x = 
+  # Dit is een test.
y;
+  
+  y = 123;

+
+  # CR or CR/LF (but not explicit \r's) in strings should be
+  # translated to LF.
+  foo = "multi
line

+  string
+  test\r";
+
+  z = 456;
}
diff --git a/tvix/eval/src/tests/nix_tests/parse-okay-dup-attrs-5.nix b/tvix/eval/src/tests/nix_tests/parse-okay-dup-attrs-5.nix
new file mode 100644
index 0000000000..f4b9efd0c5
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-okay-dup-attrs-5.nix
@@ -0,0 +1,4 @@
+{
+  services.ssh = { enable = true; };
+  services.ssh.port = 23;
+}
diff --git a/tvix/eval/src/tests/nix_tests/parse-okay-dup-attrs-6.nix b/tvix/eval/src/tests/nix_tests/parse-okay-dup-attrs-6.nix
new file mode 100644
index 0000000000..ae6d7a7693
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-okay-dup-attrs-6.nix
@@ -0,0 +1,4 @@
+{
+  services.ssh.port = 23;
+  services.ssh = { enable = true; };
+}
diff --git a/tvix/eval/src/tests/nix_tests/parse-okay-mixed-nested-attrs-1.nix b/tvix/eval/src/tests/nix_tests/parse-okay-mixed-nested-attrs-1.nix
new file mode 100644
index 0000000000..fd1001c8ca
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-okay-mixed-nested-attrs-1.nix
@@ -0,0 +1,4 @@
+{ 
+  x = { y = 3; z = 3; }; 
+  x.q = 3; 
+}
diff --git a/tvix/eval/src/tests/nix_tests/parse-okay-mixed-nested-attrs-2.nix b/tvix/eval/src/tests/nix_tests/parse-okay-mixed-nested-attrs-2.nix
new file mode 100644
index 0000000000..ad066b6803
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-okay-mixed-nested-attrs-2.nix
@@ -0,0 +1,4 @@
+{ 
+  x.q = 3; 
+  x = { y = 3; z = 3; }; 
+}
diff --git a/tvix/eval/src/tests/nix_tests/parse-okay-mixed-nested-attrs-3.nix b/tvix/eval/src/tests/nix_tests/parse-okay-mixed-nested-attrs-3.nix
new file mode 100644
index 0000000000..45a33e4803
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-okay-mixed-nested-attrs-3.nix
@@ -0,0 +1,7 @@
+{
+    services.ssh.enable = true;
+    services.ssh = { port = 123; };
+    services = {
+        httpd.enable = true;
+    };
+}
diff --git a/tvix/eval/src/tests/nix_tests/parse-okay-regression-20041027.nix b/tvix/eval/src/tests/nix_tests/parse-okay-regression-20041027.nix
new file mode 100644
index 0000000000..ae2e256eea
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-okay-regression-20041027.nix
@@ -0,0 +1,11 @@
+{stdenv, fetchurl /* pkgconfig, libX11 */ }:
+
+stdenv.mkDerivation {
+  name = "libXi-6.0.1";
+  src = fetchurl {
+    url = http://freedesktop.org/~xlibs/release/libXi-6.0.1.tar.bz2;
+    md5 = "7e935a42428d63a387b3c048be0f2756";
+  };
+/*  buildInputs = [pkgconfig];
+  propagatedBuildInputs = [libX11]; */
+}
diff --git a/tvix/eval/src/tests/nix_tests/parse-okay-regression-751.nix b/tvix/eval/src/tests/nix_tests/parse-okay-regression-751.nix
new file mode 100644
index 0000000000..05c78b3016
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-okay-regression-751.nix
@@ -0,0 +1,2 @@
+let const = a: "const"; in
+''${ const { x = "q"; }}''
diff --git a/tvix/eval/src/tests/nix_tests/parse-okay-subversion.nix b/tvix/eval/src/tests/nix_tests/parse-okay-subversion.nix
new file mode 100644
index 0000000000..356272815d
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-okay-subversion.nix
@@ -0,0 +1,43 @@
+{ localServer ? false
+, httpServer ? false
+, sslSupport ? false
+, pythonBindings ? false
+, javaSwigBindings ? false
+, javahlBindings ? false
+, stdenv, fetchurl
+, openssl ? null, httpd ? null, db4 ? null, expat, swig ? null, j2sdk ? null
+}:
+
+assert expat != null;
+assert localServer -> db4 != null;
+assert httpServer -> httpd != null && httpd.expat == expat;
+assert sslSupport -> openssl != null && (httpServer -> httpd.openssl == openssl);
+assert pythonBindings -> swig != null && swig.pythonSupport;
+assert javaSwigBindings -> swig != null && swig.javaSupport;
+assert javahlBindings -> j2sdk != null;
+
+stdenv.mkDerivation {
+  name = "subversion-1.1.1";
+
+  builder = /foo/bar;
+  src = fetchurl {
+    url = http://subversion.tigris.org/tarballs/subversion-1.1.1.tar.bz2;
+    md5 = "a180c3fe91680389c210c99def54d9e0";
+  };
+
+  # This is a hopefully temporary fix for the problem that
+  # libsvnjavahl.so isn't linked against libstdc++, which causes
+  # loading the library into the JVM to fail.
+  patches = if javahlBindings then [/javahl.patch] else [];
+
+  openssl = if sslSupport then openssl else null;
+  httpd = if httpServer then httpd else null;
+  db4 = if localServer then db4 else null;
+  swig = if pythonBindings || javaSwigBindings then swig else null;
+  python = if pythonBindings then swig.python else null;
+  j2sdk = if javaSwigBindings then swig.j2sdk else
+          if javahlBindings then j2sdk else null;
+
+  inherit expat localServer httpServer sslSupport
+          pythonBindings javaSwigBindings javahlBindings;
+}
diff --git a/tvix/eval/src/tests/nix_tests/parse-okay-url.nix b/tvix/eval/src/tests/nix_tests/parse-okay-url.nix
new file mode 100644
index 0000000000..fce3b13ee6
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/parse-okay-url.nix
@@ -0,0 +1,7 @@
+[ x:x
+  https://svn.cs.uu.nl:12443/repos/trace/trunk
+  http://www2.mplayerhq.hu/MPlayer/releases/fonts/font-arial-iso-8859-1.tar.bz2
+  http://losser.st-lab.cs.uu.nl/~armijn/.nix/gcc-3.3.4-static-nix.tar.gz
+  http://fpdownload.macromedia.com/get/shockwave/flash/english/linux/7.0r25/install_flash_player_7_linux.tar.gz
+  ftp://ftp.gtk.org/pub/gtk/v1.2/gtk+-1.2.10.tar.gz
+]
diff --git a/tvix/eval/src/tests/nix_tests/readDir/bar b/tvix/eval/src/tests/nix_tests/readDir/bar
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/readDir/bar
diff --git a/tvix/eval/src/tests/nix_tests/readDir/foo/git-hates-directories b/tvix/eval/src/tests/nix_tests/readDir/foo/git-hates-directories
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/readDir/foo/git-hates-directories