Commit graph

5 commits

Author SHA1 Message Date
Vincent Ambo
4b9178fa2a feat(tvix/eval): insert import into the builtins itself
Adding `import` to builtins causes causes a bootstrap cycle because
the `import` builtin needs to be initialised with the set of globals
before being inserted into the globals, which also must contain
itself.

To break out of the cycle this hack wraps the builtins passed to the
compiler in an `Rc` (probably sensible anyways, as they will end up
getting cloned a bunch), containing a RefCell which gives us mutable
access to the builtins.

This opens up a potentially dangerous footgun in which we could mutate
the builtins at runtime leading to different compiler invocations
seeing different builtins, so it'd be nice to have some kind of
"finalised" status for them or some such, but I'm not sure how to
represent that atm.

Change-Id: I25f8d4d2a7e8472d401c8ba2f4bbf9d86ab2abcb
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6867
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>
2022-10-07 14:24:36 +00:00
Vincent Ambo
b530e496a5 feat(tvix/eval): initial implementation of builtins.import
This adds an initial working version of builtins.import which
encapsulates the entire functionality of `import` within the builtin
itself, without requiring any changes in the compiler or VM.

The key insight that enables this is that we can simply return a Thunk
from `import` that is constructed from the output of running the
compiler and - ta-da! - no other component needs to know about it.

A couple of notes:

* builtins.import needs to capture variables like the SourceCode
  structure. This means it can not currently be constructed the same
  way as other builtins and has special handling, which leaks out to
  `eval.rs`. I have postponed dealing with that until we have this
  working a bit more.

* the `globals` are not yet passed through

* the error representation for the new variants is absolutely not done
  yet, we probably want to switch to something that supports
  cause-chaining now (like miette)

* there is no mechanism for emitting warnings at runtime; we need to
  add that

Change-Id: I3117a7ae3ff2432bf44f5ff05ad35f47faca31d5
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6857
Reviewed-by: sterni <sternenseemann@systemli.org>
Reviewed-by: wpcarro <wpcarro@gmail.com>
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>
2022-10-06 15:22:32 +00:00
Vincent Ambo
89dc26cece feat(tvix/eval): implement builtins.currentTime
Returns time since epoch in seconds.

This has a slight behaviour difference from Nix, in that we don't pin
the time between REPL entries (Nix pins it for the program lifetime),
but this is probably inconsequential as long as it is pinned during an
evaluation.

Change-Id: I010c02e93097a209d8ad69e278397c7e30e54c86
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6846
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>
Reviewed-by: wpcarro <wpcarro@gmail.com>
2022-10-04 08:03:50 +00:00
Vincent Ambo
f0179c92d3 refactor(tvix/eval): allow impure Value builtins
Allows impure builtins that have a different shape than a Rust
function pointer; specifically this is required for
builtins.currentTime which does not work in WASM.

Change-Id: I1362d8eeafe770ce4d1c5ebe4d119aeb0abb5c9b
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6849
Reviewed-by: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>
Reviewed-by: wpcarro <wpcarro@gmail.com>
2022-10-04 08:03:50 +00:00
Griffin Smith
9e16d70809 feat(tvix/eval): Sketch out impure builtins
Sketch out a new set of "impure" builtins, which supplement the existing
set of "pure" builtins but are gated behind a feature flag, which allows
them to be omitted by crates depending on tvix-eval that only want pure
evaluation, such as tvixbolt.

Change-Id: I2736017b5c9b4776bbba8758e108ec84887abd66
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6655
Reviewed-by: wpcarro <wpcarro@gmail.com>
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>
Reviewed-by: tazjin <tazjin@tvl.su>
2022-09-22 01:36:44 +00:00