This PR adds the attribute `@[univ_out_params]` for specifying which
universe levels should be treated as output parameters. By default, any
universe level that does not occur in any input parameter is considered
an output parameter.
This PR implements better support for unfolding class fields marked as
`reducible`. For example, we want to mark fields that are types such as
```lean
MonadControlT.stM : Type u -> Type u
```
The motivation is similar to our heuristic that type definitions should
be abbreviations.
Now, suppose we want to unfold `stM m (ExceptT ε m) α` using the
`.reducible` transparency setting, we want the result to be `stM m m
(MonadControl.stM m (ExceptT ε m) α)` instead of
`(instMonadControlTOfMonadControl m m (ExceptT ε m)).1 α`. The latter
would defeat the intent of marking the field as reducible, since the
instance `instMonadControlTOfMonadControl` is `[instance_reducible]` and
the resulting term would be stuck when using `.reducible` transparency
mode.
**Remark**: This feature introduces a few breakages in core and Mathlib.
So, it is disabled for now in this PR. To enable, we must use
`set_option backward.whnf.reducibleClassField true`
This PR implements preparatory work for #12179. It implements a new
feature in `isDefEq` to ensure it does not increase the transparency
level to `.default` when checking definitionally equality of implicit
arguments. This transparency level bump was introduced in Lean 3, but it
is not a performance issue and is affecting Mathlib. This PR adds the
new feature, but it is disabled by default.
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 implements a cache for the positions of class universe level
parameters that only appear in output parameter types.
During type class resolution, the cache key for a query like
`HAppend.{0, 0, ?u} (BitVec 8) (BitVec 8) ?m` should be independent of
the specific metavariable IDs in output parameter positions. To achieve
this, output parameter arguments are erased from the cache key. However,
universe levels that only appear in output parameter types (e.g., `?u`
corresponding to the result type's universe) must also be erased to
avoid cache misses when the same query is issued with different universe
metavariable IDs.
This function identifies which universe level parameter positions are
"output-only" by collecting all level param names that appear in
non-output parameter domains, then returning the positions of any level
params not in that set.
**Remark**: This PR requires a manual update stage0 because it changes
the structure of our .olean files.
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 reverts a lot of the changes done in #8308. We practically
encountered situations such as:
```
fun y (z) :=
let x := inst
mkInst x z
f y
```
Where the instance puller turns it into:
```
let x := inst
fun y (z) :=
mkInst x z
f y
```
The current heuristic now discovers `x` being in scope at the call site
of `f` and being used under a binder in `y` and thus blocks pulling in
`x` to the specialization, abstracting over an instance.
According to @zwarich this was done at the time either due to observed
stack overflows or pulling in computation into loops. With the current
configuration for abstraction in specialization it seems rather unlikely
that we pull in a non trivial computation into a loop with this. We also
practically didn't observe stack overflows in our tests or benchmarks.
Cameron speculates that the issues he observed might've been fixed
otherwise by now.
Crucial note: Deciding not to abstract over ground terms *might* cause
us to pull in computationally intensive ground terms into a loop. We
could decide to weaken this to just instance terms though of course even
computing instances might end up being non-trivial.
This PR makes the compiler produce C code that statically initializes
close terms when possible. This change reduces startup time as the terms
are directly stored in the binary instead of getting computed at
startup.
The set of terms currently supported by this mechanism are:
- string literals
- ctors called with other statically initializeable arguments
- `Name.mkStrX` and other `Name` ctors as they require special support
due to their computed field and occur frequently due to name literals.
In core there are currently 152,524 closed terms and of these 103,929
(68%) get initialized statically with this PR. The remaining 48585 ones
are not extracted because they use (potentially transitively) various
non trivial pieces of code like `stringToMessageData` etc. We might
decide to add special support for these in the future but for the moment
this feels like it's overfitting too much for core.
This PR makes the automatic first token detection in tactic docs much
more robust, in addition to making it work in modules and other contexts
where builtin tactics are not in the environment. It also adds the
ability to override the tactic's first token as the user-visible name.
Previously, first token detection would look up the parser descriptor in
the environment and process its syntax. This would be incorrect for
builtin parsers, as well as for modules in which the definition is not
loaded. Now, it instead consults the Pratt parsing table for the
`tactic` syntax category. Tests are added that ensure this keeps working
in modules, and also that the first token of all tactics that ship with
Lean are either detected unambiguously or annotated to remove ambiguity.
Closes#12038.
Drastically speeds up `isTracingEnabledFor` in the common case, which
has evolved from "no options set" to "`Elab.async` and probably some
linter options set but no `trace`".
## Breaking changes
`Lean.Options` is now an opaque type. The basic but not all of the
`KVMap` API has been redefined on top of it.
This PR fixes the `floatLetIn` pass to not move variables in case it
could break linearity (owned variables being passed with RC 1). This
mostly improves the situation in the parser which previously had many
functions that were supposed to be linear in terms of `ParserState` but
the compiler made them non-linear. For an example of how this affected
parsers:
```lean-4
def optionalFn (p : ParserFn) : ParserFn := fun c s =>
let iniSz := s.stackSize
let iniPos := s.pos
let s := p c s
let s := if s.hasError && s.pos == iniPos then s.restore iniSz iniPos else s
s.mkNode nullKind iniSz
```
previously moved the `let iniSz := ...` declaration into the `hasError`
branch. However, this means that at the point of calling the inner
parser (`p c s`), the original state `s` needs to have RC>1 because it
is used later in the `hasError` branch, breaking linearity. This fix
prevents such moves, keeping `iniSz` before the `p c s` call.
This PR implements support for user-defined attributes at
`grind_pattern`. Suppose we have declared the `grind` attribute
```lean
register_grind_attr my_grind
```
Then, we can now write
```lean
opaque f : Nat → Nat
opaque g : Nat → Nat
axiom fg : g (f x) = x
grind_pattern [my_grind] fg => g (f x)
```
