1 files changed, 64 insertions, 0 deletions
diff --git a/tvix/eval/src/tests/tvix_tests/lib.nix b/tvix/eval/src/tests/tvix_tests/lib.nix
new file mode 100644
index 0000000000..ab509bc85f
--- /dev/null
+++ b/tvix/eval/src/tests/tvix_tests/lib.nix
@@ -0,0 +1,64 @@
+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);
+
+}