This PR shifts the conversion from LCNF mono to lambda pure into the
LCNF impure phase. This is preparatory work for the upcoming refactor of
IR into LCNF impure.
The LCNF impure phase differs from the other LCNF phases in two crucial
ways:
1. I decided to have `Decl.type` be the result type as opposed to an
arrows from the parameter types to the result type. This is done because
impure does not have a notion of arrows anymore so keeping them around
for this one particular purpose would be slightly odd.
2. In order to avoid cluttering up the olean size LCNF impure saves only
the signature persistently to the disk. This is possible because we no
longer have inlining/specialization at this point of compilation so all
we need is typing information (and potentially other environment
extensions) to guide our analyses.
This PR adds the new transparency setting `@[instance_reducible]`. We
used to check whether a declaration had `instance` reducibility by using
the `isInstance` predicate. However, this was not a robust solution
because:
- We have scoped instances, and `isInstance` returns `true` only if the
scope is active.
- We have auxiliary declarations used to construct instances manually,
such as:
```lean
def lt_wfRel : WellFoundedRelation Nat
```
`isInstance` also returns `false` for this kind of declaration.
In both cases, the declaration may be (or may have been) used to
construct an instance, but `isInstance`
returns `false`. Thus, we claim it is a mistake to check the
reducibility status using `isInstance`.
`isInstance` indicates whether a declaration is available for the type
class resolution mechanism,
not its transparency status.
**We are decoupling whether a declaration is available for type class
resolution from its transparency status.**
**Remak**: We need a update stage0 to complete this feature.
---------
Co-authored-by: Sebastian Ullrich <sebasti@nullri.ch>
This PR introduces a phase separation to the LCNF IR. This is a
preparation for the merge of
the old `Lean.Compiler.IR` and the new `Lean.Compiler.LCNF` framework.
The change parametrizes all relevant `LCNF` data structures over a
`Purity` parameter and
additionally carries around proofs that the `Purity` has certain values,
depending on what's
required. This is done as opposed to indexing the types over `Purity`
because we do (almost) never
have to store the `Purity` value for phase generic structures this way.
This PR addresses a missing check in the module system where private
names that remain in the public environment map for technical reasons
(e.g. inductive constructors generated by the kernel and relied on by
the code generator) accidentally were accessible in the public scope.
This extends the specialization behavior of functions taking instance
implicits to ordinary implicit arguments that are of instance type. The
choice between the two is often made for subtle inference-related
reasons. It also affects visibility of these functions, because the
module system makes template-like decls visible to the compiler in other
modules.
This PR adjusts the experimental module system to not import the IR of
non-`meta` declarations. It does this by replacing such IR with opaque
foreign declarations on export and adjusting the new compiler
accordingly.
This PR should not be merged before the new compiler.
Based on #8664.
This PR changes the types `AltCore`, `FunDeclCore` and `CasesCore` used
in the IRs of the new compiler into the mutual inductives `Alt`,
`FunDecl` and `Cases`.
This PR replaces `Array.feraseIdx` and `Array.insertAt` with
`Array.eraseIdx` and `Array.insertIdx`, both of which take a `Nat`
argument and a tactic-provided proof that it is in bounds. We also have
`eraseIdxIfInBounds` and `insertIdxIfInBounds` which are noops if the
index is out of bounds. We also provide a `Fin` valued version of
`Array.findIdx?`. Together, these quite ergonomically improve the array
indexing safety at a number of places in the compiler/elaborator.
It addresses the code explosion issue with the old optimization.
For example, the resulting size for `Lean.Json.Parser.escapedChar`
went from 31593 to 361.
