This PR gives the `specialize` tactic the ability to instantiate
universal quantifiers other than the first using `specialize h (y := v)`
syntax. It also fixes an issue where `MVarId.assertAfter` did not record
variable alias information, and an issue where `MVarId.replace` and
`MVarId.replaceLocalDecl` did not take metavariables into account when
calculating dependencies. Additionally it fixes some uninstantiated
metavariables bugs, including one in the Infoview tactic state
hypothesis diff.
The `specialize` tactic now uses `Lean.MVarId.replace` to simplify the
implementation, and as a consequence it tries to keep the specialized
hypothesis close to its original spot in the local context.
Additional metaprogramming API:
- `Lean.Expr.getLambdaBody` to accompany `Lean.Expr.getNumHeadLambdas`
- `Lean.LocalContext.setType`, `Lean.MetavarContext.setFVarType`,
`Lean.MVarId.setFVarType`
- `Lean.MVarId.assertAfter'` to assert a new hypothesis as early as
possibly in the context where it is well-formed, as a frontend to
`Lean.MVarId.assertAfter`, which assumes the new hypothesis is
well-formed
Breaking change: metaprograms cannot assume that `MVarId`s change if
metavariables are assigned. For example, the `change` tactic will no
longer change `MVarId`s if the only effect is incidental metavariable
assignments.
Mathlib impact: this revealed many `dsimp`s that did nothing and could
be deleted.
Closes#9893
This PR adds a new, extensible `do` elaborator. Users can opt into the
new elaborator by unsetting the option `backward.do.legacy`.
New elaborators for the builtin `doElem` syntax category can be
registered with attribute `doElem_elab`. For new syntax, additionally a
control info handler must be registered with attribute
`doElem_control_info` that specifies whether the new syntax `return`s
early, `break`s, `continue`s and which `mut` vars it reassigns.
Do elaborators have type ``TSyntax `doElem → DoElemCont → DoElabM
Expr``, where `DoElabM` is essentially `TermElabM` and the `DoElemCont`
represents how the rest of the `do` block is to be elaborated. Consult
the docstrings for more details.
Breaking Changes:
* The syntax for `let pat := rhs | otherwise` and similar now scope over
the `doSeq` that follows. Furthermore, `otherwise` and the sequence that
follows are now `doSeqIndented` in order not to steal syntax from record
syntax.
Breaking Changes when opting into the new `do` elaborator by unsetting
`backward.do.legacy`:
* `do` notation now always requires `Pure`.
* `do match` is now always non-dependent. There is `do match (dependent
:= true)` that expands to a
term match as a workaround for some dependent uses.
This PR adds support for incrementally processing local declarations in
`grind`. Instead of processing all hypotheses at once during goal
initialization, `grind` now tracks which local declarations have been
processed via `Goal.nextDeclIdx` and provides APIs to process new
hypotheses incrementally.
This feature will be used by the new `SymM` monad for efficient symbolic
simulation.
This PR changes the interface of the `ForIn`, `ForIn'`, and `ForM`
typeclasses to not take a `Monad m` parameter. This is a breaking change
for most downstream `instance`s, which will will now need to assume
`[Monad m]`.
The rationale is that if the provider of an instance requires `m` to be
a Monad, they should assume this up front. This makes it possible for
the instanve to assume `LawfulMonad m` or some other stronger
requirement, and also to provided a concrete instance for a particular
`m` without assuming a non-canonical `Monad` structure on it.
Zulip: [#lean4 > Monad assumptions in fields of other typeclasses @
💬](https://leanprover.zulipchat.com/#narrow/channel/270676-lean4/topic/Monad.20assumptions.20in.20fields.20of.20other.20typeclasses/near/537102158)
This PR adds a new, inactive and unused `doElem_elab` attribute that
will allow users to register custom elaborators for `doElem`s in the
form of the new type `DoElab`. The old `do` elaborator is active by
default but can be switched off by disabling the new option
`backward.do.legacy`.
This PR cleans up `optParam`/`autoParam`/etc. annotations before
elaborating definition bodies, theorem bodies, `fun` bodies, and `let`
function bodies. Both `variable`s and binders in declaration headers are
supported.
There are no changes to `inductive`/`structure`/`axiom`/etc. processing,
just `def`/`theorem`/`example`/`instance`.
This PR implements first-class support for nondependent let expressions
in the elaborator; recall that a let expression `let x : t := v; b` is
called *nondependent* if `fun x : t => b` typechecks, and the notation
for a nondependent let expression is `have x := v; b`. Previously we
encoded `have` using the `letFun` function, but now we make use of the
`nondep` flag in the `Expr.letE` constructor for the encoding. This has
been given full support throughout the metaprogramming interface and the
elaborator. Key changes to the metaprogramming interface:
- Local context `ldecl`s with `nondep := true` are generally treated as
`cdecl`s. This is because in the body of a `have` expression the
variable is opaque. Functions like `LocalDecl.isLet` by default return
`false` for nondependent `ldecl`s. In the rare case where it is needed,
they take an additional optional `allowNondep : Bool` flag (defaults to
`false`) if the variable is being processed in a context where the value
is relevant.
- Functions such as `mkLetFVars` by default generalize nondependent let
variables and create lambda expressions for them. The
`generalizeNondepLet` flag (default true) can be set to false if `have`
expressions should be produced instead. **Breaking change:** Uses of
`letLambdaTelescope`/`mkLetFVars` need to use `generalizeNondepLet :=
false`. See the next item.
- There are now some mapping functions to make telescoping operations
more convenient. See `mapLetTelescope` and `mapLambdaLetTelescope`.
There is also `mapLetDecl` as a counterpart to `withLetDecl` for
creating `let`/`have` expressions.
- Important note about the `generalizeNondepLet` flag: it should only be
used for variables in a local context that the metaprogram "owns". Since
nondependent let variables are treated as constants in most cases, the
`value` field might refer to variables that do not exist, if for example
those variables were cleared or reverted. Using `mapLetDecl` is always
fine.
- The simplifier will cache its let dependence calculations in the
nondep field of let expressions.
- The `intro` tactic still produces *dependent* local variables. Given
that the simplifier will transform lets into haves, it would be
surprising if that would prevent `intro` from creating a local variable
whose value cannot be used.
Note that nondependence of lets is not checked by the kernel. To
external checker authors: If the elaborator gets the nondep flag wrong,
we consider this to be an elaborator error. Feel free to typecheck `letE
n t v b true` as if it were `app (lam n t b default) v` and please
report issues.
This PR follows up from #8751, which made sure the nondep flag was
preserved in the C++ interface.
This PR reworks the `simp` set around the `Id` monad, to not elide or
unfold `pure` and `Id.run`
In particular, it stops encoding the "defeq abuse" of `Id X = X` in the
statements of theorems, instead using `Id.run` and `pure` to pass back
and forth between these two spellings. Often when writing these with
`pure`, they generalize to other lawful monads; though such changes were
split off to other PRs.
This fixes the problem with the current simp set where `Id.run (pure x)`
is simplified to `Id.run x`, instead of the desirable `x`.
This is particularly bad because the` x` is sometimes inferred with type
`Id X` instead of `X`, which prevents other `simp` lemmas about `X` from
firing.
Making `Id` reducible instead is not an option, as then the `Monad`
instances would have nothing to key on.
---------
Co-authored-by: Sebastian Graf <sg@lean-fro.org>
Co-authored-by: Kim Morrison <kim@tqft.net>
Co-authored-by: Paul Reichert <6992158+datokrat@users.noreply.github.com>
This PR ensures that names suggested by tactics like `simp?` are not
shadowed by auxiliary declarations in the local context and that names
of `let rec` and `where` declarations are correctly resolved in tactic
blocks.
This PR contains the following potentially breaking changes:
* Moves the `auxDeclToFullName` map from `TermElab.Context` to
`LocalContext`.
* Refactors `Lean.Elab.Term.resolveLocalName : Name → TermElabM …` to
`Lean.resolveLocalName [MonadResolveName m] [MonadEnv m] [MonadLCtx m] :
Name → m …`.
* Refactors the `TermElabM` action `Lean.Elab.Term.withAuxDecl` to a
monad-polymorphic action `Lean.Meta.withAuxDecl`.
* Adds an optional `filter` argument to `Lean.unresolveNameGlobal`.
Closes#6706, closes#7073.
This PR moves away from using `List.get` / `List.get?` / `List.get!` and
`Array.get!`, in favour of using the `GetElem` mediated getters. In
particular it deprecates `List.get?`, `List.get!` and `Array.get?`. Also
adds `Array.back`, taking a proof, matching `List.getLast`.
This PR modifies the signature of the functions `Nat.fold`,
`Nat.foldRev`, `Nat.any`, `Nat.all`, so that the function is passed the
upper bound. This allows us to change runtime array bounds checks to
compile time checks in many places.
