This PR adds infrastructure for parallel execution across Lean's tactic
monads.
- Add IO.waitAny' to Init/System/IO.lean for waiting on task completion
- Add `Lean.Elab.Task` with `asTask` utilities for `CoreM`, `MetaM`,
`TermElabM`, `TacticM`
- Add `Lean.Elab.Parallel` with parallel execution strategies:
* `par`/`par'` - collect results in original order
* `parIter`/`parIterGreedy` - iterate over results (original or
completion order) (also variants with a cancellation token)
* `parFirst` - return first successful result
This does *not* attempt to be a monad-polymorphic framework for
parallelism. It's intentionally hard-coded to the Lean tactic monads
which I need to work with. If there's desire to make this polymorphic,
hopefully that can be done separately.
This PR renames `String.bytes` to `String.toByteArray`.
This is for two reasons: first, `toByteArray` is a better name, and
second, we have something else that wants to use the name `bytes`,
namely the function that returns in iterator over the string's bytes.
This PR renames `String.ValidPos` to `String.Pos`, `String.endValidPos`
to `String.endPos` and `String.startValidPos` to `String.startPos`.
Accordingly, the deprecations of `String.Pos` to `String.Pos.Raw` and
`String.endPos` to `String.rawEndPos` are removed early, after an
abbreviated deprecation cycle of two releases.
This PR adds an explicit normalization layer for ring constraints in the
`grind linarith` module. For example, it will be used to clean up
denominators when the ring is a field.
This PR renames the `cutsat` tactic to `lia` for better alignment with
standard terminology in the theorem proving community.
`cutsat` still works but now emits a deprecation warning and suggests
using `lia` instead via "Try this:". Both tactics have identical
behavior.
Co-authored-by: Claude <noreply@anthropic.com>
This PR ensures that users can provide `grind` proof parameters whose
types are not `forall`-quantified. Examples:
```lean
opaque f : Nat → Nat
axiom le_f (a : Nat) : a ≤ f a
example (a : Nat) : a ≤ f a := by
grind [le_f a]
example (a b : α) (h : ∀ x y : α, x = y) : a = b := by
grind [h a b]
```
This PR introduces a new `grind` option, `funCC` (enabled by default),
which extends congruence closure to *function-valued* equalities. When
`funCC` is enabled, `grind` tracks equalities of **partially applied
functions**, allowing reasoning steps such as:
```lean
a : Nat → Nat
f : (Nat → Nat) → (Nat → Nat)
h : f a = a
⊢ (f a) m = a m
g : Nat → Nat
f : Nat → Nat → Nat
h : f a = g
⊢ f a b = g b
```
Given an application `f a₁ a₂ … aₙ`, when `funCC := true` and function
equality is enabled for `f`, `grind` generates and tracks equalities for
all partial applications:
* `f a₁`
* `f a₁ a₂`
* …
* `f a₁ a₂ … aₙ`
This allows equalities such as `f a₁ = g` to propagate through further
applications.
**When is function equality enabled for a symbol?**
Function equality is enabled for `f` in the following cases:
1. `f` is **not a constant** (e.g., a lambda, a local function, or a
function parameter).
2. `f` is a **structure field projection**, provided the structure is
**not a `class`**.
3. `f` is a constant marked with `@[grind funCC]`
Users can also enable function equality for specific constants in a
single call using:
```lean
grind [funCC f, funCC g]
```
**Examples:**
```lean
example (m : Nat) (a : Nat → Nat) (f : (Nat → Nat) → (Nat → Nat)) (h : f a = a) :
f a m = a m := by
grind
example (m : Nat) (a : Nat → Nat) (f : (Nat → Nat) → (Nat → Nat)) (h : f a = a) :
f a m = a m := by
fail_if_success grind -funCC -- fails if `funCC` is disabled
grind
```
```lean
example (a b : Nat) (g : Nat → Nat) (f : Nat → Nat → Nat) (h : f a = g) :
f a b = g b := by
grind
example (a b : Nat) (g : Nat → Nat) (f : Nat → Nat → Nat) (h : f a = g) :
f a b = g b := by
fail_if_success grind -funCC
grind
```
**Enabling per-symbol with parameters or attributes**
```lean
opaque f : Nat → Nat → Nat
opaque g : Nat → Nat
example (a b c : Nat) : f a = g → b = c → f a b = g c := by
grind [funCC f, funCC g]
attribute [grind funCC] f g
example (a b c : Nat) : f a = g → b = c → f a b = g c := by
grind
```
This feature substantially improves `grind`’s support for higher-order
and partially-applied function equalities, while preserving
compatibility with first-order SMT behavior when `funCC` is disabled.
Closes#11309
This PR improves the support for `Fin n` in `grind` when `n` is not a
numeral.
- `toInt (0 : Fin n) = 0` in `grind lia`.
- `Fin.mk`-applications are treated as interpreted terms in `grind lia`.
- `Fin.val` applications are suppressed from `grind lia`
counterexamples.
This PR fixes an issue affecting `grind -revert`. In this mode, assigned
metavariables in hypotheses were not being instantiated. This issue was
affecting two files in Mathlib.
This PR fixes a local declaration internalization in `grind` that was
exposed when using `grind -revert`. This bug was affecting a `grind`
proof in Mathlib.
This PR improves the error message encountered in the case of a type
class instance resolution failure, and adds an error explanation that
discusses the common new-user case of binary operation overloading and
points to the `trace.Meta.synthInstance` option for advanced debugging.
## Example
```lean4
def f (x : String) := x + x
```
Before:
```
failed to synthesize
HAdd String String ?m.5
Hint: Additional diagnostic information may be available using the `set_option diagnostics true` command.
```
After:
```
failed to synthesize instance of type class
HAdd String String ?m.5
Hint: Type class instance resolution failures can be inspected with the `set_option trace.Meta.synthInstance true` command.
Error code: lean.failedToSynthesizeTypeclassInstance
[View explanation](https://lean-lang.org/doc/reference/latest/find/?domain=Manual.errorExplanation&name=lean.failedToSynthesizeTypeclassInstance)
```
The error message is changed in three important ways:
* Explains *what* failed to synthesize, using the "type class"
terminology that's more likely to be recognized than the "instance"
terminology
* Points to the `trace.Meta.synthInstance` option which is otherwise
nearly undiscoverable but is quite powerful (see also
leanprover/reference-manual#663 which is adding commentary on this
option)
* Gives an error explanation link (which won't actually work until the
next release after this is merged) which prioritizes the common-case
explanation of using the wrong binary operation
This PR fixes a bug in the propagation rules for `ite` and `dite` used
in `grind`. The bug prevented equalities from being propagated to the
satellite solvers. Here is an example affected by this issue.
```lean
example
[LE α] [LT α] [Std.IsLinearOrder α] [Std.LawfulOrderLT α]
[Lean.Grind.CommRing α] [DecidableLE α] [Lean.Grind.OrderedRing α]
(a b c : α) :
(if a - b ≤ -(a - b) then -(a - b) else a - b) ≤
((if a - c ≤ -(a - c) then -(a - c) else a - c) + if c - d ≤ -(c - d) then -(c - d) else c - d) +
if b - d ≤ -(b - d) then -(b - d) else b - d := by
grind
```
This PR adds support for decidable equality of empty lists and empty
arrays. Decidable equality for lists and arrays is suitably modified so
that all diamonds are definitionally equal.
Following #9302, the strong condition of definitionally equal under
`with_reducible_and_instances` is tested. This also moves some of the
comments added in #9302 out of docstrings.
---------
Co-authored-by: Aaron Liu <aaronliu2008@outlook.com>
Co-authored-by: Eric Wieser <wieser.eric@gmail.com>
Global `attribute` commands on non-local declarations are impossible to
track granularly a priori and so should be preserved by `shake` by
default. A new `shake` option could be added to ignore these
dependencies for evaluation.
This PR adds `Std.Slice.Pattern` instances for `p : Char -> Prop` as
long as `DecidablePred p`, to allow things like `"hello".dropWhile (· =
'h')`.
To achieve this, we refactor `ForwardPattern` and friends to be
"non-uniform", i.e., the class is now `ForwardPattern pat`, not
`ForwardPattern ρ` (where `pat : ρ`).
This PR splits the single grind_lint.lean test (50+ seconds) into 7
separate files that each run in under 7 seconds:
- grind_lint_list.lean (5.7s): List namespace with exceptions
- grind_lint_array.lean (4.6s): Array namespace
- grind_lint_bitvec.lean (3.9s): BitVec namespace with exceptions
- grind_lint_std_hashmap.lean (6.8s): Std hash map/set namespaces
- grind_lint_std_treemap.lean (~6s): Std tree map/set namespaces
- grind_lint_std_misc.lean (~5s): Std.Do, Std.Range, Std.Tactic
- grind_lint_misc.lean (5.5s): All other non-Lean namespaces
Each file maintains complete namespace coverage and preserves all
existing exceptions. The split enables better CI parallelization and
faster feedback.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-authored-by: Claude <noreply@anthropic.com>
This PR implements support for arbitrary `grind` parameters. The feature
is similar to the one available in `simp`, where a proof term is treated
as a local universe-polymorphic lemma. This feature relies on `grind
-revert` (see #11248). For example, users can now write:
```lean
def snd (p : α × β) : β := p.2
theorem snd_eq (a : α) (b : β) : snd (a, b) = b := rfl
/--
trace: [grind.ematch.instance] snd_eq (a + 1): snd (a + 1, Type) = Type
[grind.ematch.instance] snd_eq (a + 1): snd (a + 1, true) = true
-/
#guard_msgs (trace) in
set_option trace.grind.ematch.instance true in
example (a : Nat) : (snd (a + 1, true), snd (a + 1, Type), snd (2, 2)) = (true, Type, snd (2, 2)) := by
grind [snd_eq (a + 1)]
```
Note that in the example above, `snd_eq` is instantiated only twice, but
with different universe parameters.
As described in #11248, the new feature cannot be used with `grind
+revert`.
This PR marks the automatically generated `sizeOf` theorems as `grind`
theorems.
closes#11259
Note: Requested update stage0, we need it to be able to solve example in
the issue above.
```lean
example (a: Nat) (b: Nat): sizeOf a < sizeOf (a, b) := by
grind
```
This PR introduces a function `String.split` which is based on
`String.Slice.split` and therefore supports all pattern types and
returns a `Std.Iter String.Slice`.
This supersedes the functions `String.splitOn` and `String.splitToList`,
and we remove all all uses of these functions from core. They will be
deprecated in a future PR.
Migrating from `String.splitOn` and `String.splitToList` is easy: we
introduce functions `Iter.toStringList` and `Iter.toStringArray` that
can be used to conveniently go from `Std.Iter String.Slice` to `List
String` and `Array String`, so for example `s.splitOn "foo"` can be
replaced by `s.split "foo" |>.toStringList`.
This PR adds a `Unit` assumption to alternatives of the splitter that
would otherwise not have arguments. This fixes#11211.
In practice these argument-less alternatives did not cause wrong
behavior, as the motive when used with `split` is always a function
type. But it is better to be safe here (maybe someone uses splitters in
other ways), it may increase the effectiveness of #10184 and simplifies
#11220.
The perf impact is insignificant in the grand scheme of things on
stdlib, but the change is effective:
```
~/lean4 $ build/release/stage1/bin/lean tests/lean/run/matchSplitStats.lean
969 splitters found
455 splitters are const defs
~/lean4 $ build/release/stage2/bin/lean tests/lean/run/matchSplitStats.lean
969 splitters found
829 splitters are const defs
```
This PR implements the option `revert`, which is set to `false` by
default. To recover the old `grind` behavior, you should use `grind
+revert`. Previously, `grind` used the `RevSimpIntro` idiom, i.e., it
would revert all hypotheses and then re-introduce them while simplifying
and applying eager `cases`. This idiom created several problems:
* Users reported that `grind` would include unnecessary parameters. See
[here](https://leanprover.zulipchat.com/#narrow/channel/270676-lean4/topic/Grind.20aggressively.20includes.20local.20hypotheses.2E/near/554887715).
* Unnecessary section variables were also being introduced. See the new
test contributed by Sebastian Graf.
* Finally, it prevented us from supporting arbitrary parameters as we do
in `simp`. In `simp`, I implemented a mechanism that simulates local
universe-polymorphic theorems, but this approach could not be used in
`grind` because there is no mechanism for reverting (and re-introducing)
local universe-polymorphic theorems. Adding such a mechanism would
require substantial work: I would need to modify the local context
object. I considered maintaining a substitution from the original
variables to the new ones, but this is also tricky, because the mapping
would have to be stored in the `grind` goal objects, and it is not just
a simple mapping. After reverting everything, I would need to keep a
sequence of original variables that must be added to the mapping as we
re-introduce them, but eager case splits complicate this quite a bit.
The whole approach felt overly messy.
The new behavior `grind -revert` addresses all these issues. None of the
`grind` proofs in our test suite broke after we fixed the bugs exposed
by the new feature. That said, the traces and counterexamples produced
by `grind` are different. The new proof terms are also different.
This PR introduces a clarifying note to "undefined identifier" error
messages when the undefined identifier is in a syntactic position where
autobinding might generally apply, but where and autobinding is
disabled. A corresponding note is made in the `lean.unknownIdentifier`
error explanation.
The core intended audience for this error message change is "newcomer
who would otherwise be baffled why the thing that works in this Mathlib
project gets 'unknown identifier' errors in this non-Mathlib project."
## Modified behavior
### Example 1
```lean4
set_option autoImplicit true in
set_option relaxedAutoImplicit false in
def thisBreaks (x : α₂) (y : size₂) := ()
```
Before:
```
Unknown identifier `size₂`
```
After:
```
Unknown identifier `size₂`
Note: It is not possible to treat `size₂` as an implicitly bound variable here because it has multiple characters while the `relaxedAutoImplicit` option is set to `false`.
```
### Example 2
```lean4
set_option autoImplicit false in
def thisAlsoBreaks (x : α₃) (y : size₃) := ()
```
Before:
```
Unknown identifier `α₃`
Unknown identifier `size₃`
```
After:
```
Unknown identifier `α₃`
Note: It is not possible to treat `α₃` as an implicitly bound variable here because the `autoImplicit` option is set to `false`.
Unknown identifier `size₃`
Note: It is not possible to treat `size₃` as an implicitly bound variable here because the `autoImplicit` option is set to `false`.
```
## How this works
The elaboration process knows whether it is considering syntax where we
be able to auto-bind implicits thanks to information in the
`Lean.Elab.Term.Context`.
Before this PR, this contains:
* `autoBoundImplicit`, a boolean that is true when we are considering
syntax that might be able to auto-bind implicit AND when the
`autoImplicit` flag is set to true
* `autoBoundImplicits`, an array of `Expr` variables that we've
autobound
After this PR, this contains:
* `autoBoundImplicitCtx`, an option which is `some` **whenever** we are
considering syntax that might be able to auto-bind implicit, and carries
the array of exprs as well as a copy of the `autoImplicit` flag's value.
(The latter lets us re-implement the `autoBoundImplicit` flag for
backward compatibility.)
Therefore, rather than having access to "elaboration is in an
autobinding context && flag is enabled", it's possible to recover both
of those individual values, and give different information to the user
in cases where we didn't attempt autobinding but would have if different
options had been set.
## Rationale
The revised error message avoids offering much guidance — it doesn't
actively suggest setting the option to a different value or suggest
adding an implicit binding. Care needs to be taken here to make sure
advice is not misleading; as the accepted RFC in #6462 points out, a
substantial portion of autobinding failures are just going to be
misspellings.
I considered and then rejected a code action here to that would add a
local `set_option autoImplicit true`. This seems undesirable or
counterproductive — if a project like Mathlib has proactively disabled
`autoImplicit`, its odd to be pushing local exceptions.
A hint prompting the user to add an implicit binding would be more
proper, but only in certain circumstances — we want to be conservative
in suggesting specific code actions! In a situation like this one, we'd
want to _avoid_ giving the suggestion of adding a `{HasArr}` binding,
which I think either requires tricky heuristics or means we'd want the
elaboration to play through the consequences of auto-binding and make
sure it doesn't cause any follow-on errors before suggesting adding an
implicit binding.
```
set_option autoImplicit true
set_option relaxedAutoImplicit false
instance has_arr : HasArr Preorder := { Arr := Function }
```
Additionally, it seems like it would make the most sense to offer to
auto-bind _all_ the relevant unknown identifiers at once. To avoid being
misleading, this too would seem to require playing through the
consequences of autobinding before being able to safely suggest the
change. This is enough additional complexity that I'm leaving it for
future work.
---------
Co-authored-by: David Thrane Christiansen <david@davidchristiansen.dk>
This PR redefines `String.take` and variants to operate on
`String.Slice`. While previously functions returning a substring of the
input sometimes returned `String` and sometimes returned
`Substring.Raw`, they now uniformly return `String.Slice`.
This is a BREAKING change, because many functions now have a different
return type. So for example, if `s` is a string and `f` is a function
accepting a string, `f (s.drop 1)` will no longer compile because
`s.drop 1` is a `String.Slice`. To fix this, insert a call to `copy` to
restore the old behavior: `f (s.drop 1).copy`.
Of course, in many cases, there will be more efficient options. For
example, don't write `f <| s.drop 1 |>.copy |>.dropEnd 1 |>.copy`, write
`f <| s.drop 1 |>.dropEnd 1 |>.copy` instead. Also, instead of `(s.drop
1).copy = "Hello"`, write `s.drop 1 == "Hello".toSlice` instead.
This PR implements `elabToSyntax` for creating scoped syntax `s :
Syntax` for an arbitrary elaborator `el : Option Expr -> TermElabM Expr`
such that `elabTerm s = el`.
Roundtripping example implementing an elaborator imitating `let`:
```lean
elab "lett " decl:letDecl ";" e:term : term <= ty? => do
let elabE (ty? : Option Expr) : TermElabM Expr := do elabTerm e ty?
elabToSyntax elabE fun body => do
elabTerm (← `(let $decl:letDecl; $body)) ty?
#guard lett x := 42; (x + 1) = 43
```
This PR provides a polymorphic `ForIn` instance for slices and an MPL
`spec` lemma for the iteration over slices using `for ... in`. It also
provides a version specialized to `Subarray`.
This PR changes how sparse case expressions represent the
none-of-the-above information. Instead of of many `x.ctorIdx ≠ i`
hypotheses, it introduces a single `Nat.hasNotBit mask x.ctorIdx`
hypothesis which compresses that information into a bitmask. This avoids
a quadratic overhead during splitter generation, where all n assumptions
would be refined through `.subst` and `.cases` constructions for all n
assumption of the splitter alternative.
The definition of `Nat.hasNotBit` uses `Nat.rightShift` which is fiddly
to get to reduce well, especially on open terms and with `Meta.whnf`.
Some experimentation was needed to find proof terms that work, these are
all put together in the `Lean.Meta.HasNotBit` module.
Fixes#11183
---------
Co-authored-by: Rob23oba <152706811+Rob23oba@users.noreply.github.com>
This ensures that no `grind` annotated theorem, simply by being
instantiated, causes a chain of >20 further instantiations, with a small
list of documented exceptions.
This PR modifies the `try?` framework, so each subsidiary tactic runs
with a separate `maxHeartbeats` budget.
---------
Co-authored-by: Rob23oba <152706811+Rob23oba@users.noreply.github.com>
This PR has `#grind_list check` produce a "Try this:" suggestion with
`#grind_list inspect` commands, as this is usually the next step in
dealing with problematic cases. We also fix the grind pattern for one
theorem, as part of testing the workflow. More to follow.
This PR fixes a few minor issues in the new `Action` framework used in
`grind`. The goal is to eventually delete the old `SearchM`
infrastructure. The main `solve` function used by `grind` is now based
on the `Action` framework. The PR also deletes dead code in `SearchM`.
This PR renames `Substring` to `Substring.Raw`.
This is to signify its status as a second-class citizen (not deprecated,
but no real plans for verification, like `String.Pos.Raw`) and to free
up the name `Substring` for a possible future type `String.Substring :
String -> Type` so that `s.Substring` is the type of substrings of `s`.
The functions `String.toSubstring` and `String.toSubstring'` will remain
for now for bootstrapping reasons.
This PR implements `try?` using the new `finish?` infrastructure. It
also removes the old tracing infrastructure, which is now obsolete.
Example:
```lean
/--
info: Try these:
[apply] grind
[apply] grind only [findIdx, insert, = mem_indices_of_mem, = getElem?_neg, = getElem?_pos, = HashMap.mem_insert,
= HashMap.getElem_insert, #1bba]
[apply] grind only [findIdx, insert, = mem_indices_of_mem, = getElem?_neg, = getElem?_pos, = HashMap.mem_insert,
= HashMap.getElem_insert]
[apply] grind =>
instantiate only [findIdx, insert, = mem_indices_of_mem]
instantiate only [= getElem?_neg, = getElem?_pos]
cases #1bba
· instantiate only [findIdx]
· instantiate only
instantiate only [= HashMap.mem_insert, = HashMap.getElem_insert]
-/
#guard_msgs in
example (m : IndexMap α β) (a : α) (b : β) :
(m.insert a b).findIdx a = if h : a ∈ m then m.findIdx a else m.size := by
try?
```
This PR modifies the error message that is returned when more than one
synthetic metavariable can't be resolved.
The two heuristics used for prioritization are:
- prefer typeclass problems associated with small ranges over typeclass
problems associated with large ranges (I'm pretty confident in this
heuristic)
- do not prefer typeclass problems over other kinds of errors (not as
confident in this heuristic)
This PR uses the new `grind_pattern` constraints to fix cases where an
unbounded number of theorem instantiations would be generated for
certain theorems in the standard library.
