This PR introduces the `@[specs]` attribute. It can be applied to
(certain) type class instances and define “specification theorems” for
the class’ operations, by taking the equational theorems of the
implementation function mentioned in the type class instance and
rephrasing them in terms of the overloaded operations. Fixes#5295.
Example:
```
inductive L α where
| nil : L α
| cons : α → L α → L α
def L.beqImpl [BEq α] : L α → L α → Bool
| nil, nil => true
| cons x xs, cons y ys => x == y && L.beqImpl xs ys
| _, _ => false
@[method_specs] instance [BEq α] : BEq (L α) := ⟨L.beqImpl⟩
/--
info: theorem instBEqL.beq_spec_2.{u_1} : ∀ {α : Type u_1} [inst : BEq α] (x_2 : α) (xs : L α) (y : α) (ys : L α),
(L.cons x_2 xs == L.cons y ys) = (x_2 == y && xs == ys)
-/
#guard_msgs(pass trace, all) in
#print sig instBEqL.beq_spec_2
```
It also introduces the `method_specs_norm` simpset to allow registering
further normalization of the theorems. The intended use of this is to
rewrite, say, `Append.append` to the `HAppend.hAppend` (i.e. `++`) that
the user wants to see. Library annotations to follow in a separate PR.
This PR adds a procedure that efficiently transforms `let` expressions
into `have` expressions (`Meta.letToHave`). This is exposed as the
`let_to_have` tactic.
It uses the `withTrackingZetaDelta` technique: the expression is
typechecked, and any `let` variables that don't enter the zeta delta set
are nondependent. The procedure uses a number of heuristics to limit the
amount of typechecking performed. For example, it is ok to skip
subexpressions that do not contain fvars, mvars, or `let`s.
This PR adds additional infrastructure for error message formatting.
Specifically, it adds convenience formatters for hints and notes,
including the ability to attach code actions to hint messages using a
"Try This"-like widget, along with several convenience formatters for
message data.
---------
Co-authored-by: Joachim Breitner <mail@joachim-breitner.de>
This PR adds the `binderNameHint` gadget. It can be used in rewrite and
simp rules to preserve a user-provided name where possible.
The expression `binderNameHint v binder e` defined to be `e`.
If it is used on the right-hand side of an equation that is applied by a
tactic like `rw` or `simp`,
and `v` is a local variable, and `binder` is an expression that (after
beta-reduction) is a binder
(so `fun w => …` or `∀ w, …`), then it will rename `v` to the name used
in the binder, and remove
the `binderNameHint`.
A typical use of this gadget would be as follows; the gadget ensures
that after rewriting, the local
variable is still `name`, and not `x`:
```
theorem all_eq_not_any_not (l : List α) (p : α → Bool) :
l.all p = !l.any fun x => binderNameHint x p (!p x) := sorry
example (names : List String) : names.all (fun name => "Waldo".isPrefixOf name) = true := by
rw [all_eq_not_any_not]
-- ⊢ (!names.any fun name => !"Waldo".isPrefixOf name) = true
```
This gadget is supported by `simp`, `dsimp` and `rw` in the
right-hand-side of an equation, but not
in hypotheses or by other tactics.
This PR makes it harder to create "fake" theorems about definitions that
are stubbed-out with `sorry` by ensuring that each `sorry` is not
definitionally equal to any other. For example, this now fails:
```lean
example : (sorry : Nat) = sorry := rfl -- fails
```
However, this still succeeds, since the `sorry` is a single
indeterminate `Nat`:
```lean
def f (n : Nat) : Nat := sorry
example : f 0 = f 1 := rfl -- succeeds
```
One can be more careful by putting parameters to the right of the colon:
```lean
def f : (n : Nat) → Nat := sorry
example : f 0 = f 1 := rfl -- fails
```
Most sources of synthetic sorries (recall: a sorry that originates from
the elaborator) are now unique, except for elaboration errors, since
making these unique tends to cause a confusing cascade of errors. In
general, however, such sorries are labeled. This enables "go to
definition" on `sorry` in the Infoview, which brings you to its origin.
The option `set_option pp.sorrySource true` causes the pretty printer to
show source position information on sorries.
**Details:**
* Adds `Lean.Meta.mkLabeledSorry`, which creates a sorry that is labeled
with its source position. For example, `(sorry : Nat)` might elaborate
to
```
sorryAx (Lean.Name → Nat) false
`lean.foo.12.8.12.13.8.13._sorry._@.lean.foo._hyg.153
```
It can either be made unique (like the above) or merely labeled. Labeled
sorries use an encoding that does not impact defeq:
```
sorryAx (Unit → Nat) false (Function.const Lean.Name ()
`lean.foo.14.7.13.7.13.69._sorry._@.lean.foo._hyg.174)
```
* Makes the `sorry` term, the `sorry` tactic, and every elaboration
failure create labeled sorries. Most are unique sorries, but some
elaboration errors are labeled sorries.
* Renames `OmissionInfo` to `DelabTermInfo` and adds configuration
options to control LSP interactions. One field is a source position to
use for "go to definition". This is used to implement "go to definition"
on labeled sorries.
* Makes hovering over a labeled `sorry` show something friendlier than
that full `sorryAx` expression. Instead, the first hover shows the
simplified ``sorry `«lean.foo:48:11»``. Hovering over that hover shows
the full `sorryAx`. Setting `set_option pp.sorrySource true` makes
`sorry` always start with printing with this source position
information.
* Removes `Lean.Meta.mkSyntheticSorry` in favor of `Lean.Meta.mkSorry`
and `Lean.Meta.mkLabeledSorry`.
* Changes `sorryAx` so that the `synthetic` argument is no longer
optional.
* Gives `addPPExplicitToExposeDiff` awareness of labeled sorries. It can
set `pp.sorrySource` when source positions differ.
* Modifies the delaborator framework so that delaborators can set Info
themselves without it being overwritten.
Incidentally closes#4972.
Inspired by [this Zulip
thread](https://leanprover.zulipchat.com/#narrow/channel/287929-mathlib4/topic/Is.20a.20.60definition_wanted.60.20keyword.20possible.3F/near/477260277).
This adds a number of lemmas for simplification of `Bool` and `Prop`
terms. It pulls lemmas from Mathlib and adds additional lemmas where
confluence or consistency suggested they are needed.
It has been tested against Mathlib using some automated test
infrastructure.
That testing module is not yet included in this PR, but will be included
as part of this.
Note. There are currently some comments saying the origin of the simp
rule. These will be removed prior to merging, but are added to clarify
where the rule came from during review.
---------
Co-authored-by: Scott Morrison <scott.morrison@gmail.com>
This is still a draft PR, but includes the core exact? and apply?
tactics.
Still need to convert to builtin syntax and test on Std.
---------
Co-authored-by: David Thrane Christiansen <david@davidchristiansen.dk>
in all uses of `CasesOnApp`, we treat `MatcherApp`s the same way,
dupliating a fair amount of relatively hairy code (and there is more to
come).
However, the `MatcherApp` abstraction is perfectly capable of
also representing `casesOn` applications, at least for the use cases
encountered so far.
So lets just (optionally) include `casesOn` applications when looking
for matchers,
and remove the `CasesOnApp` abstraction completely.
Moves the `@[coe]` attribute and associated elaborators/delaborators
from Std to Lean.
---------
Co-authored-by: Leonardo de Moura <leomoura@amazon.com>
We don't use the following hack anymore:
- /- HACK: `fvarId` is not in the scope of `mvarId`
- If this generates problems in the future, we should update the metavariable declarations. -/
- assignExprMVar mvarId (mkFVar fvarId)
This hack was corrupting the `InfoTree`.
We need `MetaM` methods such as `isProp` to improve `ppGoal`.
This commit also moves `currNamespace` and `openDecls` to
`Core.Context`. Without this change, `Meta.ppExpr` was not taking
`open` commands into account.
