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2022-09-06 r/4676 refactor(tvix/eval): simplify thunk representationsVincent Ambo1-7/+7
For now, do not distinguish between closing and non-closing thunks, it will make the initial implementation easier. See Knuth etc. Change-Id: I0bd51e0f89f2c77e90bac63b507e5027b649e3d8 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6346 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-06 r/4673 feat(tvix/eval): introduce Value::Thunk variantVincent Ambo2-1/+61
Introduces the representation of runtime thunks, that is lazily evaluated values. Their representation is very similar to closures. Change-Id: I24d1ab7947c070ae72ca6260a7bbe6198bc8c7c5 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6343 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-06 r/4667 feat(tvix/eval): implement OpFinalise instructionVincent Ambo1-0/+11
This instruction finalises the initialisation of deferred upvalues in closures (and soon, thunks). The compiler does not yet emit this instruction, some more accounting is needed for that. Change-Id: Ic4181b26e19779e206f51e17388559400da5f93a Reviewed-on: https://cl.tvl.fyi/c/depot/+/6337 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-06 r/4666 feat(tvix/eval): set up deferred upvalues at runtimeVincent Ambo1-1/+5
This will leave a sentinel value in the upvalue slot in which the actual value is to be captured after resolution once a scope is fully set up. Change-Id: I12b37b0dc8d32603b03e675c3bd039468e70b354 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6336 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-06 r/4659 fix(tvix/eval): instantiate *new* closures from blueprints each timeVincent Ambo2-5/+8
The previous closure refactoring introduced a bug in which the same closure object would get mutated constantly for each instance of a closure, which is incorrect behaviour. This commit instead introduces an explicit new Value variant for the internal "blueprint" that the compiler generates (essentially just the lambda) and uses this variant to construct the closure at runtime. If the blueprint ever leaks out to a user somehow that is a critical bug and tvix-eval will panic. As a ~treat~ test for this, the fibonacci function is being used as it is a self-recursive closure (i.e. different instantiations of the same "blueprint") getting called with different values and it's good to have it around. Change-Id: I485de675e9bb0c599ed7d5dc0f001eb34ab4c15f Reviewed-on: https://cl.tvl.fyi/c/depot/+/6323 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-06 r/4658 fix(tvix/eval): correctly thread through dynamic upvaluesVincent Ambo1-1/+7
This puts together the puzzle pieces for threading dynamic upvalues (that is, upvalues resolved from the `with`-stack) all the way through. Reading the test case enclosed in this commit and walking through it is recommended to understand what problem is being tackled here. In short, because the compiler can not statically know *which* with-scope a dynamic argument is resolved from it needs to lay the groundwork for resolving from *all* possible scopes. There are multiple different approaches to doing this. The approach chosen in this commit is that if a dynamic upvalue is detected, the compiler will emit instructions to close over this dynamic value in *all* enclosing lambda contexts. It uses a new instruction for this that will leave around a sentinel value in case an identifier could not be resolved, and wire the location of this found value (or sentinel) up through the upvalues to the next level of nesting. In this tradeoff, tvix potentially closes over more upvalues than are needed (but in practice, how often do people create *really* deep `with`-stacks? and in *this* kind of code situation? maybe we should even warn for this!) but avoids keeping the entire attribute sets themselves around. Looking at the test case, each surrounding closure will close over *all* dynamic identifiers that are referenced later on visible to it, but only the last one for each identifier will actually end up being used. This also covers our bases for an additional edge-case this creates, in which an identifier potentially resolves to a dynamic upvalue *and* to a dynamic value within the function's own scope (again, would anyone really do this?) by introducing a resolution instruction for that particular case. There is likely some potential for cleaning up this code which is quite ugly in some parts, but as this implementation is now carefully calibrated to work I decided it is time to commit it and clean it up in subsequent commits. Change-Id: Ib701e3e6da39bd2c95938d1384036ff4f9fb3749 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6322 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-06 r/4651 refactor(tvix/eval): encapsulate internal mutability within ClosureVincent Ambo1-7/+30
This is required to efficiently construct the upvalue array at runtime, as there are situations where during Closure construction multiple things already have a reference to the closure (e.g. a self-reference). Change-Id: I35263b845fdc695dc873de489f5168d39b370f6a Reviewed-on: https://cl.tvl.fyi/c/depot/+/6312 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-04 r/4635 feat(tvix/eval): implement upvalue resolution in `with` scopesVincent Ambo2-0/+17
These need to be handled specially by the runtime if the compiler determines that a given local must be resolved via `with`. Note that this implementation has a bug: It currently allows `with` inside of nested lambdas to shadow statically known identifiers. This will be cleaned up in the next commit. Change-Id: If196b99cbd1a0f2dbb4a40a0e88cdb09a009c6b9 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6299 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-03 r/4626 feat(tvix/eval): add Value::to_closureVincent Ambo1-0/+11
... same as the others Change-Id: I9c8868388c10b0b6484c5bdd3799d801296c6979 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6292 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-09-03 r/4625 feat(tvix/eval): compile creation of closure objectsVincent Ambo1-1/+11
Fully implements the instructions for compiling closure objects (without runtime handling yet). Closure (and thunk) objects are created at runtime by capturing all known upvalues. To represent this, the instructions for creating them need to have a variable number of arguments. Due to that, this commit introduces new variants in OpCode that are not actually operations, but data. If the VM is implemented correctly, the instruction pointer should never point at these. Due to this, the VM will panic if it sees a data operand during an execution run. Change-Id: Ic56b49b3a42736dc437751e76df0e89c8d0619c6 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6291 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-09-03 r/4623 feat(tvix/eval): implement compilation of upvalue accessVincent Ambo1-0/+2
This adds a new upvalue tracking structure in the compiler to resolve upvalues and track their positions within a function when compiling a closure. The compiler will emit runtime upvalue access instructions after this commit, but the creation of the runtime closure object etc. is not yet wired up. Change-Id: Ib0c2c25f686bfd45f797c528753068858e3a770d Reviewed-on: https://cl.tvl.fyi/c/depot/+/6289 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-09-03 r/4616 refactor(tvix/eval): avoid cloning in NixAttrs::update if possibleVincent Ambo1-20/+27
Refactors the update function to take the attribute sets by value instead. To facilitate this, we use an equivalent of the currently unstable `Rc::clone_or_unwrap` in the VM when encountering attribute sets, so that in cases where the only references to the attrs being updated are the ones on the stack those clones are avoided completely. This does make update() a little bit more tricky internally, as some optimised branches can directly return the moved value, and others need to destructure with ownership. For this reason there are now two different match statements handling the different ownership cases. Change-Id: Ia77d3ba5c86afb75b9f1f51758bda61729ba5aab Reviewed-on: https://cl.tvl.fyi/c/depot/+/6279 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-03 r/4614 refactor(tvix/eval): slightly more readable AttrsRep::selectVincent Ambo1-11/+5
Suggestion from grfn in cl/6158. Change-Id: I16dcf2296a5ec5d299d5a080ca099b8eda6c254e Reviewed-on: https://cl.tvl.fyi/c/depot/+/6278 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-09-03 r/4613 refactor(tvix/eval): rename Value::NotFound & OpAttrOrNotFoundVincent Ambo1-3/+3
grfn suggested clearer naming for these in cl/6166. Change-Id: I83164bf1d1902ebd42272e9d5d63819a0f6a72c5 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6277 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-09-03 r/4611 refactor(tvix/eval): get rid of Value::Blackhole variantVincent Ambo2-5/+3
This is no longer needed for anything and the extra clone here is not really more costly than constructing a blackhole value in a different place. Change-Id: I5c63085b1b4418b629ea58a42e3bfe9a9b586d76 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6275 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-09-03 r/4608 fix(tvix/eval): address all current clippy lintsVincent Ambo2-2/+2
Change-Id: I758fc4f3b9078de7ca6228a75a4351c3e085c4cf Reviewed-on: https://cl.tvl.fyi/c/depot/+/6272 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-09-03 r/4607 fix(tvix/eval): correctly escape `${` in stringsVincent Ambo1-11/+15
Without this escape, it is possible for Nix to produce escaped representations which are not literal Nix values again. This was fixed in upstream Nix in https://github.com/NixOS/nix/pull/4012 (though only for eval, not in the REPL) and the updated test is picked from upstream after that commit. Because we run the C++ Nix tests against our test suite as well, this also bumps our custom Nix 2.3 to a commit that includes the cherry-picked fix from the PR above. Change-Id: I478547ade65f655c606ec46f7143932064192283 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6271 Reviewed-by: grfn <grfn@gws.fyi> Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI
2022-09-03 r/4605 refactor(tvix/eval): introduce Closure struct in Value typeVincent Ambo2-5/+10
This struct will carry the upvalue machinery in addition to the lambda itself. For now, all lambdas are wrapped in closures (though technically analysis of the environment can later remove innermost Closure wrapper, but this optimisation may not be worth it). Change-Id: If2b68549ec1ea4ab838fdc47a2181c694ac937f2 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6269 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-09-02 r/4601 refactor(tvix/eval): avoid a use of Value::BlackholeVincent Ambo1-2/+2
The blackhole allocation is not going to be cheaper than cloning this. Change-Id: Id3ad44812decb4392830be06645e67bb0a982b96 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6267 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-09-02 r/4597 refactor(tvix/eval): add NixAttrs::contains functionVincent Ambo1-0/+12
This avoids copying around the value more than needed. Change-Id: I35949d16dad7fb8f76e0f641eaccf48322144777 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6263 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-02 r/4596 feat(tvix/eval): implement builtins.catAttrsVincent Ambo1-0/+4
Change-Id: Idf92ac82438fbfcf7b2f6e058830e4744637d8c6 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6262 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-02 r/4592 refactor(tvix/eval): implement clearer mechanism for globalsVincent Ambo1-0/+8
The set of things that can leak out of `builtins` into the global scope is statically known (it is what Nix 2.3 leaks there, essentially). This is a mild change over the previous mechanism, where instead at the point where the `builtins` set is constructed we "lift" the globals out of there (if they exist). This way users will still eventually be able to add additional builtins, HOWEVER they will not be able to leak them into the global scope. Note that upstream Nix technically leaks _all_ builtins into the global scope using the `__*` prefix, but we are trying to avoid this in Tvix if it is not required in nixpkgs. Change-Id: Ie9dec2ce33740134f3b2464eba3749f421dd5953 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6258 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-02 r/4588 feat(tvix/eval): introduce mechanism for defining builtinsVincent Ambo1-0/+13
Adds a new builtins module in which builtins can be constructed. The functions in this module should return a correctly structured value to be passed to the compiler's `globals`. This is wired up all the way to the compiler with an example `toString` builtin, available as a global. Note that this does not yet actually behave like the real toString, which has some differences from `Display`. Change-Id: Ibb5f6fbe6207782fdf2434435567fc1bd80039a5 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6254 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-02 r/4585 feat(tvix/eval): add initial representation of builtinsVincent Ambo2-1/+71
Builtins are represented as a Rust function pointer that accepts a vector of arguments, which represents variable arity builtins. Change-Id: Ibab7e662a646caf1172695d876d2f55e187c03dd Reviewed-on: https://cl.tvl.fyi/c/depot/+/6251 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-09-01 r/4576 refactor(tvix/eval): return a lambda from the compilerVincent Ambo1-4/+15
Changes the internal compiler plumbing to not just return a chunk of code, but the same chunk wrapped inside of a lambda value. This is one more step towards compiling runtime lambdas. Change-Id: If0035f8e65a2970c5ae123fc068a2396e1d8fd72 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6240 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-09-01 r/4574 feat(tvix/eval): introduce initial `Lambda` typeVincent Ambo2-0/+18
Change-Id: Ifa9766f5ffeff99e926936bafd697e885e733b78 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6238 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-09-01 r/4571 feat(tvix/eval): carry optional SyntaxNode in error typeVincent Ambo2-16/+23
This starts paving the way for nicer, source-code based error reporting. Right now the code paths in the VM do not emit annotated errors, as we do not yet preserve that structure from the compiler. However, error emitting code paths in the compiler have been amended to include known nodes. Change-Id: I1b74410ffd891c40cd913361bd73c4336ec8aa5b Reviewed-on: https://cl.tvl.fyi/c/depot/+/6235 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-09-01 r/4568 fix(tvix/eval): fix several string escapingsVincent Ambo1-2/+4
These were missing an additional level of escaping, silly oversight caught by an upstream test. Change-Id: I0312084475e4b88c83945614e9aa5b34c6bc3ec2 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6232 Reviewed-by: sterni <sternenseemann@systemli.org> Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-08-31 r/4555 feat(tvix/eval): add Value::as_attrs methodVincent Ambo1-0/+10
Change-Id: I2f39122ac85b67837335aab308d845907160e132 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6221 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org> Reviewed-by: grfn <grfn@gws.fyi>
2022-08-30 r/4542 fix(tvix/eval): allow use of ? operator on non-set typesVincent Ambo1-1/+1
Nix allows this, but always returns false. Tvix needs to do the same. Change-Id: Ic9eec90834a0d0969eea5316d5c25032d3691d94 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6209 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-08-30 r/4541 fix(tvix/eval): emit correct count in OpAttrPathVincent Ambo1-1/+1
Not sure how exactly this snuck in, but it caused some subtle breakages in deeply nested attribute sets. Change-Id: I8049ce912405d3750031f79cc8d86ff1c3c02c2b Reviewed-on: https://cl.tvl.fyi/c/depot/+/6208 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-08-30 r/4540 docs(tvix/eval): Use correct syntax for module doc commentsVincent Ambo3-11/+10
Change-Id: I35741856f34b86a538f226a8eaf8806edede60ec Reviewed-on: https://cl.tvl.fyi/c/depot/+/6207 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-08-30 r/4539 chore(tvix/eval): minor readability improvement in attrsVincent Ambo1-12/+9
Change-Id: If9d9eaf60934e96ec4b41c57818afe0c2a99c862 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6206 Reviewed-by: grfn <grfn@gws.fyi> Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI
2022-08-30 r/4538 refactor(tvix/eval): remove Error::InvalidKeyTypeVincent Ambo1-5/+1
We're confident that we're handling all branches that can reasonably occur from valid AST, any other cases should be considered a critical evaluator bug and panic rather than surfacing something that looks like user error. Change-Id: If96966eb32b8ff12fcaeb9ea3b0c8fc51b6abd11 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6205 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-08-30 r/4537 fix(tvix/eval): address various clippy lintsVincent Ambo2-25/+13
Change-Id: I3ea0f51475e80948adfeb5d1620c1f2665cc39bc Reviewed-on: https://cl.tvl.fyi/c/depot/+/6201 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-08-30 r/4536 feat(tvix/eval): implement attribute set equalityVincent Ambo1-2/+48
Change-Id: Ia25f02610f2575e5e7fca81643e05b40f4a07820 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6200 Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI
2022-08-30 r/4535 fix(tvix/eval): `null` in dynamic attribute keys skips the elementVincent Ambo1-0/+7
This is actually *tested* behaviour in C++ Nix, so we need to implement it here, too. Change-Id: Ic4a4659a2f04cdd928cbe78a85dae90401515371 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6199 Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI
2022-08-27 r/4516 chore(tvix/eval): add variant_size_differences warning to `Value`Vincent Ambo1-0/+1
Change-Id: I2f4719a81512a9a970edf22390afed490125bda7 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6182 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-08-27 r/4515 feat(tvix/eval): add Path representation to Value enumVincent Ambo1-1/+4
Change-Id: I4827384201912131ea8fc2362188dcd862b94852 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6181 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi> Reviewed-by: sterni <sternenseemann@systemli.org>
2022-08-27 r/4514 refactor(tvix/eval): use `write!` macro instead of `f.write_fmt`Vincent Ambo2-8/+7
grfn pointed out in cl/6082 that this is actually the desugaring of the write! macro, so it doesn't make sense to write it out. Change-Id: If7c055b042ad22b034722aec1eaadba92736d684 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6180 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org> Reviewed-by: grfn <grfn@gws.fyi>
2022-08-27 r/4512 chore(tvix/eval): explicitly set #[repr(transparent)] on wrappersVincent Ambo3-0/+3
For representation wrappers that are used to control the visibility of type internals, this ensures that the wrapper does not increase the size of the type. In practice, the optimiser likely does this anyways but it is good to guarantee it. Change-Id: Ic6df7d668fe6006dfbd5b6cfcfc2088afa95b810 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6178 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-08-26 r/4499 feat(tvix/vm): add opcodes for new Value::NotFound sentinelVincent Ambo1-3/+5
This sentinel value is going to be used for certain nested accesses into attribute sets. There is a new instruction similar to `OpAttrsSelect` which leaves the sentinel on the stack if a key is not found, instead of raising an error. Additionally, a new jump instruction makes its jump operation conditional on finding such a sentinel value. Change-Id: I2642f0a0bcc85bbe0ead68ea09a7dd794dbedeac Reviewed-on: https://cl.tvl.fyi/c/depot/+/6166 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-08-26 r/4498 refactor(tvix/value): replace static representation with SmolStrVincent Ambo2-10/+11
The only uses of the static variant were for `"name"` and `"value"`, which are both small enough to fit into a SmolStr. The size of NixString accomodates `String` anyways, so we may as well inline them. Additionally smol_str is already in the dependency graph because rnix uses it, and using it for representations of identifiers is sensible. Change-Id: I9969312256d1657d69128e54c47dc7294a18ce58 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6165 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org> Reviewed-by: grfn <grfn@gws.fyi>
2022-08-26 r/4497 chore(tvix/eval): implement improved Display for internal valuesVincent Ambo1-1/+2
Having these visible more explicitly is useful while debugging. Change-Id: I86b497883063d32792b635eb4514b7aeae484af4 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6164 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org> Reviewed-by: grfn <grfn@gws.fyi>
2022-08-26 r/4492 feat(tvix/eval): implement attribute set access operatorVincent Ambo1-0/+25
Fairly straightforward, handling the optimised representations manually and otherwise delegating to BTreeMap. Note that parsing of raw identifiers is not yet implemented. Encountering an identifier node usually means that there is locals access going on, so we need a special case for compiling a node in such a way that an identifier's literal value ends up on the stack. Change-Id: I13fbab7ac657b17ef3f4c5859fe737c321890c8a Reviewed-on: https://cl.tvl.fyi/c/depot/+/6158 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org> Reviewed-by: grfn <grfn@gws.fyi>
2022-08-26 r/4491 fix(tvix/eval): add operation to assert boolean typeVincent Ambo1-0/+4
This operation is required because both sides of the logical operators are strictly evaluated by Nix, even if the resulting value is not used further. For example, in our implementation of `&&`, if the left-hand side is `true`, then the result of the expression is simply the right-hand side value. This value must be asserted to be a boolean for the semantics of the language to work correctly. Change-Id: I34f5364f2a444753fa1d8b0a1a2b2d9cdf7c6700 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6157 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org> Reviewed-by: grfn <grfn@gws.fyi>
2022-08-25 r/4483 feat(tvix/eval): implement if/else expressionsVincent Ambo1-2/+2
These expressions use simple jumps to skip the correct expression conditionally in the bytecode by advancing the instruction pointer. Note that these expressions are already covered by a test behind the `nix_tests` feature flag, but adding more is probably sensible. Change-Id: Ibe0eba95d216321c883d3b6b5816e2ab6fe7eef1 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6148 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi> Reviewed-by: sterni <sternenseemann@systemli.org>
2022-08-25 r/4482 refactor(tvix/value): hide internal string representationVincent Ambo1-9/+12
Wraps the string representation in an additional newtype struct with a private field in order to hide the representation from other modules. This is done in order to avoid accidental leakage of the internals outside of value::string. In fact, this caught a mistake in the compiler module which was directly constructing an internal variant. Change-Id: If4b627d3cff7ab9cd50ca1a3ac73245d4dcf7aef Reviewed-on: https://cl.tvl.fyi/c/depot/+/6147 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-08-25 r/4481 refactor(tvix/value): ensure internal attrs representation is hiddenVincent Ambo2-47/+53
Wraps the attrs representation in an additional newtype struct with a private field in order to hide the representation from other modules. This is done in order to avoid accidental leakage of the internals outside of value::attrs. Change-Id: I68d1d02514aa0443df4c39801001a3f1f6cc5d5c Reviewed-on: https://cl.tvl.fyi/c/depot/+/6146 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-08-25 r/4480 refactor(tvix/eval): encapsulate list construction in value::listVincent Ambo1-1/+12
Ensuring that the implementation is not leaking out of the module lets us keep things open for optimisations (e.g. empty list or pairs through tuples). Change-Id: I18fd9b7740f28c55736471e16c6b4095a05dd6d0 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6145 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
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