feat: add option pp.mvars.delayed (#5643)
Where before we had ```lean #check fun x : Nat => ?a -- fun x ↦ ?m.7 x : (x : Nat) → ?m.6 x ``` Now by default we have ```lean #check fun x : Nat => ?a -- fun x => ?a : (x : Nat) → ?m.6 x ``` In particular, delayed assignment metavariables such as `?m.7` pretty print using the name of the metavariable they are delayed assigned to, suppressing the bound variables used in the delayed assignment (hence `?a` rather than `?a x`). Hovering over `?a` shows `?m.7 x`. The benefit is that users can see the user-provided name in local contexts. A justification for this pretty printing choice is that `?m.7 x` is supposed to stand for `?a`, and furthermore it is just as opaque to assignment in defeq as `?a` is (however, when synthetic opaque metavariables are made assignable, delayed assignments can be a little less assignable than true synthetic opaque metavariables). The original pretty printing behavior can be recovered using `set_option pp.mvars.delayed true`. This PR also extends the documentation for holes and synthetic holes, with some technical details about what delayed assignments are. This likely should be moved to the reference manual, but for now it is included in this docstring. (This PR is a simplified version of #3494, which has a round-trippable notation for delayed assignments. The pretty printing in this PR is unlikely to round trip, but it is better than the current situation, which is that delayed assignment metavariables never round trip, and plus it does not require introducing a new notation.)
This commit is contained in:
Kyle Miller
GitHub
parent
6cdede33fb
commit
bd46319aee
14 changed files with 108 additions and 26 deletions
|
|
@ -140,11 +140,68 @@ def optSemicolon (p : Parser) : Parser :=
|
|||
/-- The universe of propositions. `Prop ≡ Sort 0`. -/
|
||||
@[builtin_term_parser] def prop := leading_parser
|
||||
"Prop"
|
||||
/-- A placeholder term, to be synthesized by unification. -/
|
||||
/--
|
||||
A *hole* (or *placeholder term*), which stands for an unknown term that is expected to be inferred based on context.
|
||||
For example, in `@id _ Nat.zero`, the `_` must be the type of `Nat.zero`, which is `Nat`.
|
||||
|
||||
The way this works is that holes create fresh metavariables.
|
||||
The elaborator is allowed to assign terms to metavariables while it is checking definitional equalities.
|
||||
This is often known as *unification*.
|
||||
|
||||
Normally, all holes must be solved for. However, there are a few contexts where this is not necessary:
|
||||
* In `match` patterns, holes are catch-all patterns.
|
||||
* In some tactics, such as `refine'` and `apply`, unsolved-for placeholders become new goals.
|
||||
|
||||
Related concept: implicit parameters are automatically filled in with holes during the elaboration process.
|
||||
|
||||
See also `?m` syntax (synthetic holes).
|
||||
-/
|
||||
@[builtin_term_parser] def hole := leading_parser
|
||||
"_"
|
||||
/-- Parses a "synthetic hole", that is, `?foo` or `?_`.
|
||||
This syntax is used to construct named metavariables. -/
|
||||
/--
|
||||
A *synthetic hole* (or *synthetic placeholder*), which stands for an unknown term that should be synthesized using tactics.
|
||||
- `?_` creates a fresh metavariable with an auto-generated name.
|
||||
- `?m` either refers to a pre-existing metavariable named `m` or creates a fresh metavariable with that name.
|
||||
|
||||
In particular, the synthetic hole syntax creates "synthetic opaque metavariables",
|
||||
the same kind of metavariable used to represent goals in the tactic state.
|
||||
|
||||
Synthetic holes are similar to holes in that `_` also creates metavariables,
|
||||
but synthetic opaque metavariables have some different properties:
|
||||
- In tactics such as `refine`, only synthetic holes yield new goals.
|
||||
- During elaboration, unification will not solve for synthetic opaque metavariables, they are "opaque".
|
||||
This is to prevent counterintuitive behavior such as disappearing goals.
|
||||
- When synthetic holes appear under binders, they capture local variables using a more complicated mechanism known as delayed assignment.
|
||||
|
||||
## Delayed assigned metavariables
|
||||
|
||||
This section gives an overview of some technical details of synthetic holes, which you should feel free to skip.
|
||||
Understanding delayed assignments is mainly useful for those who are working on tactics and other metaprogramming.
|
||||
It is included here until there is a suitable place for it in the reference manual.
|
||||
|
||||
When a synthetic hole appears under a binding construct, such as for example `fun (x : α) (y : β) => ?s`,
|
||||
the system creates a *delayed assignment*. This consists of
|
||||
1. A metavariable `?m` of type `(x : α) → (y : β) → γ x y` whose local context is the local context outside the `fun`,
|
||||
where `γ x y` is the type of `?s`. Recall that `x` and `y` appear in the local context of `?s`.
|
||||
2. A delayed assigment record associating `?m` to `?s` and the variables `#[x, y]` in the local context of `?s`
|
||||
|
||||
Then, this function elaborates as `fun (x : α) (y : β) => ?m x y`, where one should understand `x` and `y` here
|
||||
as being De Bruijn indexes, since Lean uses the locally nameless encoding of lambda calculus.
|
||||
|
||||
Once `?s` is fully solved for, in the sense that after metavariable instantiation it is a metavariable-free term `e`,
|
||||
then we can make the assignment `?m := fun (x' : α) (y' : β) => e[x := x', y := y']`.
|
||||
(Implementation note: Lean only instantiates full applications `?m x' y'` of delayed assigned metavariables, to skip forming this function.)
|
||||
This delayed assignment mechanism is essential to the operation of basic tactics like `intro`,
|
||||
and a good mental model is that it is a way to "apply" the metavariable `?s` by substituting values in for some of its local variables.
|
||||
While it would be easier to immediately assign `?s := ?m x y`,
|
||||
delayed assigment preserves `?s` as an unsolved-for metavariable with a local context that still contains `x` and `y`,
|
||||
which is exactly what tactics like `intro` need.
|
||||
|
||||
By default, delayed assigned metavariables pretty print with what they are delayed assigned to.
|
||||
The delayed assigned metavariables themselves can be pretty printed using `set_option pp.mvars.delayed true`.
|
||||
|
||||
For more information, see the "Gruesome details" module docstrings in `Lean.MetavarContext`.
|
||||
-/
|
||||
@[builtin_term_parser] def syntheticHole := leading_parser
|
||||
"?" >> (ident <|> "_")
|
||||
/--
|
||||
|
|
@ -451,7 +508,7 @@ def withAnonymousAntiquot := leading_parser
|
|||
@[builtin_term_parser] def «trailing_parser» := leading_parser:leadPrec
|
||||
"trailing_parser" >> optExprPrecedence >> optExprPrecedence >> ppSpace >> termParser
|
||||
|
||||
/--
|
||||
/--
|
||||
Indicates that an argument to a function marked `@[extern]` is borrowed.
|
||||
|
||||
Being borrowed only affects the ABI and runtime behavior of the function when compiled or interpreted. From the perspective of Lean's type system, this annotation has no effect. It similarly has no effect on functions not marked `@[extern]`.
|
||||
|
|
|
|||
|
|
@ -570,6 +570,25 @@ def withOverApp (arity : Nat) (x : Delab) : Delab := do
|
|||
withAnnotateTermInfo x
|
||||
delabAppCore (n - arity) delabHead (unexpand := false)
|
||||
|
||||
@[builtin_delab app]
|
||||
def delabDelayedAssignedMVar : Delab := whenNotPPOption getPPMVarsDelayed do
|
||||
let .mvar mvarId := (← getExpr).getAppFn | failure
|
||||
let some decl ← getDelayedMVarAssignment? mvarId | failure
|
||||
withOverApp decl.fvars.size do
|
||||
let args := (← getExpr).getAppArgs
|
||||
-- Only delaborate using decl.mvarIdPending if the delayed mvar is applied to fvars
|
||||
guard <| args.all Expr.isFVar
|
||||
withTypeAscription (cond := ← getPPOption getPPMVarsWithType) do
|
||||
if ← getPPOption getPPMVars then
|
||||
let mvarDecl ← decl.mvarIdPending.getDecl
|
||||
let n :=
|
||||
match mvarDecl.userName with
|
||||
| .anonymous => decl.mvarIdPending.name.replacePrefix `_uniq `m
|
||||
| n => n
|
||||
`(?$(mkIdent n))
|
||||
else
|
||||
`(?_)
|
||||
|
||||
/-- State for `delabAppMatch` and helpers. -/
|
||||
structure AppMatchState where
|
||||
info : MatcherInfo
|
||||
|
|
|
|||
|
|
@ -95,6 +95,11 @@ register_builtin_option pp.mvars.withType : Bool := {
|
|||
group := "pp"
|
||||
descr := "(pretty printer) display metavariables with a type ascription"
|
||||
}
|
||||
register_builtin_option pp.mvars.delayed : Bool := {
|
||||
defValue := false
|
||||
group := "pp"
|
||||
descr := "(pretty printer) display delayed assigned metavariables when true, otherwise display what they are assigned to"
|
||||
}
|
||||
register_builtin_option pp.beta : Bool := {
|
||||
defValue := false
|
||||
group := "pp"
|
||||
|
|
@ -244,6 +249,7 @@ def getPPPrivateNames (o : Options) : Bool := o.get pp.privateNames.name (getPPA
|
|||
def getPPInstantiateMVars (o : Options) : Bool := o.get pp.instantiateMVars.name pp.instantiateMVars.defValue
|
||||
def getPPMVars (o : Options) : Bool := o.get pp.mvars.name pp.mvars.defValue
|
||||
def getPPMVarsWithType (o : Options) : Bool := o.get pp.mvars.withType.name pp.mvars.withType.defValue
|
||||
def getPPMVarsDelayed (o : Options) : Bool := o.get pp.mvars.delayed.name (pp.mvars.delayed.defValue || getPPAll o)
|
||||
def getPPBeta (o : Options) : Bool := o.get pp.beta.name pp.beta.defValue
|
||||
def getPPSafeShadowing (o : Options) : Bool := o.get pp.safeShadowing.name pp.safeShadowing.defValue
|
||||
def getPPProofs (o : Options) : Bool := o.get pp.proofs.name (pp.proofs.defValue || getPPAll o)
|
||||
|
|
|
|||
|
|
@ -1,4 +1,4 @@
|
|||
fun α [Repr α] => repr : (α : Type u_1) → [inst : Repr α] → α → Std.Format
|
||||
fun x y => x : (x : ?m) → ?m x → ?m
|
||||
funParen.lean:4:12-4:16: error: invalid pattern, constructor or constant marked with '[match_pattern]' expected
|
||||
fun x => ?m x : (x : ?m) → ?m x
|
||||
fun x => ?m : (x : ?m) → ?m x
|
||||
|
|
|
|||
|
|
@ -4,5 +4,5 @@
|
|||
{"start": {"line": 4, "character": 29}, "end": {"line": 4, "character": 30}},
|
||||
"contents":
|
||||
{"value":
|
||||
"```lean\ninstDecidableTrue : Decidable True\n```\n***\nA placeholder term, to be synthesized by unification. \n***\n*import Init.Core*",
|
||||
"```lean\ninstDecidableTrue : Decidable True\n```\n***\nA *hole* (or *placeholder term*), which stands for an unknown term that is expected to be inferred based on context.\nFor example, in `@id _ Nat.zero`, the `_` must be the type of `Nat.zero`, which is `Nat`.\n\nThe way this works is that holes create fresh metavariables.\nThe elaborator is allowed to assign terms to metavariables while it is checking definitional equalities.\nThis is often known as *unification*.\n\nNormally, all holes must be solved for. However, there are a few contexts where this is not necessary:\n* In `match` patterns, holes are catch-all patterns.\n* In some tactics, such as `refine'` and `apply`, unsolved-for placeholders become new goals.\n\nRelated concept: implicit parameters are automatically filled in with holes during the elaboration process.\n\nSee also `?m` syntax (synthetic holes).\n\n***\n*import Init.Core*",
|
||||
"kind": "markdown"}}
|
||||
|
|
|
|||
|
|
@ -507,7 +507,7 @@
|
|||
"end": {"line": 252, "character": 10}},
|
||||
"contents":
|
||||
{"value":
|
||||
"```lean\nℕ\n```\n***\nA placeholder term, to be synthesized by unification. ",
|
||||
"```lean\nℕ\n```\n***\nA *hole* (or *placeholder term*), which stands for an unknown term that is expected to be inferred based on context.\nFor example, in `@id _ Nat.zero`, the `_` must be the type of `Nat.zero`, which is `Nat`.\n\nThe way this works is that holes create fresh metavariables.\nThe elaborator is allowed to assign terms to metavariables while it is checking definitional equalities.\nThis is often known as *unification*.\n\nNormally, all holes must be solved for. However, there are a few contexts where this is not necessary:\n* In `match` patterns, holes are catch-all patterns.\n* In some tactics, such as `refine'` and `apply`, unsolved-for placeholders become new goals.\n\nRelated concept: implicit parameters are automatically filled in with holes during the elaboration process.\n\nSee also `?m` syntax (synthetic holes).\n",
|
||||
"kind": "markdown"}}
|
||||
{"textDocument": {"uri": "file:///hover.lean"},
|
||||
"position": {"line": 252, "character": 11}}
|
||||
|
|
@ -573,7 +573,7 @@
|
|||
{"start": {"line": 269, "character": 2}, "end": {"line": 269, "character": 3}},
|
||||
"contents":
|
||||
{"value":
|
||||
"```lean\nlet x :=\n match 0 with\n | x => 0;\nℕ\n```\n***\nA placeholder term, to be synthesized by unification. ",
|
||||
"```lean\nlet x :=\n match 0 with\n | x => 0;\nℕ\n```\n***\nA *hole* (or *placeholder term*), which stands for an unknown term that is expected to be inferred based on context.\nFor example, in `@id _ Nat.zero`, the `_` must be the type of `Nat.zero`, which is `Nat`.\n\nThe way this works is that holes create fresh metavariables.\nThe elaborator is allowed to assign terms to metavariables while it is checking definitional equalities.\nThis is often known as *unification*.\n\nNormally, all holes must be solved for. However, there are a few contexts where this is not necessary:\n* In `match` patterns, holes are catch-all patterns.\n* In some tactics, such as `refine'` and `apply`, unsolved-for placeholders become new goals.\n\nRelated concept: implicit parameters are automatically filled in with holes during the elaboration process.\n\nSee also `?m` syntax (synthetic holes).\n",
|
||||
"kind": "markdown"}}
|
||||
{"textDocument": {"uri": "file:///hover.lean"},
|
||||
"position": {"line": 272, "character": 4}}
|
||||
|
|
|
|||
|
|
@ -4,7 +4,7 @@
|
|||
{"start": {"line": 1, "character": 5}, "end": {"line": 1, "character": 6}},
|
||||
"contents":
|
||||
{"value":
|
||||
"```lean\nNat\n```\n***\nA placeholder term, to be synthesized by unification. ",
|
||||
"```lean\nNat\n```\n***\nA *hole* (or *placeholder term*), which stands for an unknown term that is expected to be inferred based on context.\nFor example, in `@id _ Nat.zero`, the `_` must be the type of `Nat.zero`, which is `Nat`.\n\nThe way this works is that holes create fresh metavariables.\nThe elaborator is allowed to assign terms to metavariables while it is checking definitional equalities.\nThis is often known as *unification*.\n\nNormally, all holes must be solved for. However, there are a few contexts where this is not necessary:\n* In `match` patterns, holes are catch-all patterns.\n* In some tactics, such as `refine'` and `apply`, unsolved-for placeholders become new goals.\n\nRelated concept: implicit parameters are automatically filled in with holes during the elaboration process.\n\nSee also `?m` syntax (synthetic holes).\n",
|
||||
"kind": "markdown"}}
|
||||
{"textDocument": {"uri": "file:///hoverBinderUndescore.lean"},
|
||||
"position": {"line": 1, "character": 7}}
|
||||
|
|
@ -12,7 +12,7 @@
|
|||
{"start": {"line": 1, "character": 7}, "end": {"line": 1, "character": 8}},
|
||||
"contents":
|
||||
{"value":
|
||||
"```lean\nBool\n```\n***\nA placeholder term, to be synthesized by unification. ",
|
||||
"```lean\nBool\n```\n***\nA *hole* (or *placeholder term*), which stands for an unknown term that is expected to be inferred based on context.\nFor example, in `@id _ Nat.zero`, the `_` must be the type of `Nat.zero`, which is `Nat`.\n\nThe way this works is that holes create fresh metavariables.\nThe elaborator is allowed to assign terms to metavariables while it is checking definitional equalities.\nThis is often known as *unification*.\n\nNormally, all holes must be solved for. However, there are a few contexts where this is not necessary:\n* In `match` patterns, holes are catch-all patterns.\n* In some tactics, such as `refine'` and `apply`, unsolved-for placeholders become new goals.\n\nRelated concept: implicit parameters are automatically filled in with holes during the elaboration process.\n\nSee also `?m` syntax (synthetic holes).\n",
|
||||
"kind": "markdown"}}
|
||||
{"textDocument": {"uri": "file:///hoverBinderUndescore.lean"},
|
||||
"position": {"line": 6, "character": 6}}
|
||||
|
|
@ -20,7 +20,7 @@
|
|||
{"start": {"line": 6, "character": 6}, "end": {"line": 6, "character": 7}},
|
||||
"contents":
|
||||
{"value":
|
||||
"```lean\nNat\n```\n***\nA placeholder term, to be synthesized by unification. ",
|
||||
"```lean\nNat\n```\n***\nA *hole* (or *placeholder term*), which stands for an unknown term that is expected to be inferred based on context.\nFor example, in `@id _ Nat.zero`, the `_` must be the type of `Nat.zero`, which is `Nat`.\n\nThe way this works is that holes create fresh metavariables.\nThe elaborator is allowed to assign terms to metavariables while it is checking definitional equalities.\nThis is often known as *unification*.\n\nNormally, all holes must be solved for. However, there are a few contexts where this is not necessary:\n* In `match` patterns, holes are catch-all patterns.\n* In some tactics, such as `refine'` and `apply`, unsolved-for placeholders become new goals.\n\nRelated concept: implicit parameters are automatically filled in with holes during the elaboration process.\n\nSee also `?m` syntax (synthetic holes).\n",
|
||||
"kind": "markdown"}}
|
||||
{"textDocument": {"uri": "file:///hoverBinderUndescore.lean"},
|
||||
"position": {"line": 6, "character": 8}}
|
||||
|
|
@ -28,7 +28,7 @@
|
|||
{"start": {"line": 6, "character": 8}, "end": {"line": 6, "character": 9}},
|
||||
"contents":
|
||||
{"value":
|
||||
"```lean\nBool\n```\n***\nA placeholder term, to be synthesized by unification. ",
|
||||
"```lean\nBool\n```\n***\nA *hole* (or *placeholder term*), which stands for an unknown term that is expected to be inferred based on context.\nFor example, in `@id _ Nat.zero`, the `_` must be the type of `Nat.zero`, which is `Nat`.\n\nThe way this works is that holes create fresh metavariables.\nThe elaborator is allowed to assign terms to metavariables while it is checking definitional equalities.\nThis is often known as *unification*.\n\nNormally, all holes must be solved for. However, there are a few contexts where this is not necessary:\n* In `match` patterns, holes are catch-all patterns.\n* In some tactics, such as `refine'` and `apply`, unsolved-for placeholders become new goals.\n\nRelated concept: implicit parameters are automatically filled in with holes during the elaboration process.\n\nSee also `?m` syntax (synthetic holes).\n",
|
||||
"kind": "markdown"}}
|
||||
{"textDocument": {"uri": "file:///hoverBinderUndescore.lean"},
|
||||
"position": {"line": 11, "character": 6}}
|
||||
|
|
@ -36,7 +36,7 @@
|
|||
{"start": {"line": 11, "character": 6}, "end": {"line": 11, "character": 7}},
|
||||
"contents":
|
||||
{"value":
|
||||
"```lean\nNat\n```\n***\nA placeholder term, to be synthesized by unification. ",
|
||||
"```lean\nNat\n```\n***\nA *hole* (or *placeholder term*), which stands for an unknown term that is expected to be inferred based on context.\nFor example, in `@id _ Nat.zero`, the `_` must be the type of `Nat.zero`, which is `Nat`.\n\nThe way this works is that holes create fresh metavariables.\nThe elaborator is allowed to assign terms to metavariables while it is checking definitional equalities.\nThis is often known as *unification*.\n\nNormally, all holes must be solved for. However, there are a few contexts where this is not necessary:\n* In `match` patterns, holes are catch-all patterns.\n* In some tactics, such as `refine'` and `apply`, unsolved-for placeholders become new goals.\n\nRelated concept: implicit parameters are automatically filled in with holes during the elaboration process.\n\nSee also `?m` syntax (synthetic holes).\n",
|
||||
"kind": "markdown"}}
|
||||
{"textDocument": {"uri": "file:///hoverBinderUndescore.lean"},
|
||||
"position": {"line": 11, "character": 8}}
|
||||
|
|
@ -44,5 +44,5 @@
|
|||
{"start": {"line": 11, "character": 8}, "end": {"line": 11, "character": 9}},
|
||||
"contents":
|
||||
{"value":
|
||||
"```lean\nBool\n```\n***\nA placeholder term, to be synthesized by unification. ",
|
||||
"```lean\nBool\n```\n***\nA *hole* (or *placeholder term*), which stands for an unknown term that is expected to be inferred based on context.\nFor example, in `@id _ Nat.zero`, the `_` must be the type of `Nat.zero`, which is `Nat`.\n\nThe way this works is that holes create fresh metavariables.\nThe elaborator is allowed to assign terms to metavariables while it is checking definitional equalities.\nThis is often known as *unification*.\n\nNormally, all holes must be solved for. However, there are a few contexts where this is not necessary:\n* In `match` patterns, holes are catch-all patterns.\n* In some tactics, such as `refine'` and `apply`, unsolved-for placeholders become new goals.\n\nRelated concept: implicit parameters are automatically filled in with holes during the elaboration process.\n\nSee also `?m` syntax (synthetic holes).\n",
|
||||
"kind": "markdown"}}
|
||||
|
|
|
|||
|
|
@ -4,7 +4,7 @@
|
|||
{"start": {"line": 1, "character": 9}, "end": {"line": 1, "character": 11}},
|
||||
"contents":
|
||||
{"value":
|
||||
"```lean\nFalse\n```\n***\nParses a \"synthetic hole\", that is, `?foo` or `?_`.\nThis syntax is used to construct named metavariables. ",
|
||||
"```lean\nFalse\n```\n***\nA *synthetic hole* (or *synthetic placeholder*), which stands for an unknown term that should be synthesized using tactics.\n- `?_` creates a fresh metavariable with an auto-generated name.\n- `?m` either refers to a pre-existing metavariable named `m` or creates a fresh metavariable with that name.\n\nIn particular, the synthetic hole syntax creates \"synthetic opaque metavariables\",\nthe same kind of metavariable used to represent goals in the tactic state.\n\nSynthetic holes are similar to holes in that `_` also creates metavariables,\nbut synthetic opaque metavariables have some different properties:\n- In tactics such as `refine`, only synthetic holes yield new goals.\n- During elaboration, unification will not solve for synthetic opaque metavariables, they are \"opaque\".\n This is to prevent counterintuitive behavior such as disappearing goals.\n- When synthetic holes appear under binders, they capture local variables using a more complicated mechanism known as delayed assignment.\n\n## Delayed assigned metavariables\n\nThis section gives an overview of some technical details of synthetic holes, which you should feel free to skip.\nUnderstanding delayed assignments is mainly useful for those who are working on tactics and other metaprogramming.\nIt is included here until there is a suitable place for it in the reference manual.\n\nWhen a synthetic hole appears under a binding construct, such as for example `fun (x : α) (y : β) => ?s`,\nthe system creates a *delayed assignment*. This consists of\n1. A metavariable `?m` of type `(x : α) → (y : β) → γ x y` whose local context is the local context outside the `fun`,\n where `γ x y` is the type of `?s`. Recall that `x` and `y` appear in the local context of `?s`.\n2. A delayed assigment record associating `?m` to `?s` and the variables `#[x, y]` in the local context of `?s`\n\nThen, this function elaborates as `fun (x : α) (y : β) => ?m x y`, where one should understand `x` and `y` here\nas being De Bruijn indexes, since Lean uses the locally nameless encoding of lambda calculus.\n\nOnce `?s` is fully solved for, in the sense that after metavariable instantiation it is a metavariable-free term `e`,\nthen we can make the assignment `?m := fun (x' : α) (y' : β) => e[x := x', y := y']`.\n(Implementation note: Lean only instantiates full applications `?m x' y'` of delayed assigned metavariables, to skip forming this function.)\nThis delayed assignment mechanism is essential to the operation of basic tactics like `intro`,\nand a good mental model is that it is a way to \"apply\" the metavariable `?s` by substituting values in for some of its local variables.\nWhile it would be easier to immediately assign `?s := ?m x y`,\ndelayed assigment preserves `?s` as an unsolved-for metavariable with a local context that still contains `x` and `y`,\nwhich is exactly what tactics like `intro` need.\n\nBy default, delayed assigned metavariables pretty print with what they are delayed assigned to.\nThe delayed assigned metavariables themselves can be pretty printed using `set_option pp.mvars.delayed true`.\n\nFor more information, see the \"Gruesome details\" module docstrings in `Lean.MetavarContext`.\n",
|
||||
"kind": "markdown"}}
|
||||
{"textDocument": {"uri": "file:///issue5021.lean"},
|
||||
"position": {"line": 1, "character": 10}}
|
||||
|
|
@ -12,7 +12,7 @@
|
|||
{"start": {"line": 1, "character": 9}, "end": {"line": 1, "character": 11}},
|
||||
"contents":
|
||||
{"value":
|
||||
"```lean\nFalse\n```\n***\nParses a \"synthetic hole\", that is, `?foo` or `?_`.\nThis syntax is used to construct named metavariables. ",
|
||||
"```lean\nFalse\n```\n***\nA *synthetic hole* (or *synthetic placeholder*), which stands for an unknown term that should be synthesized using tactics.\n- `?_` creates a fresh metavariable with an auto-generated name.\n- `?m` either refers to a pre-existing metavariable named `m` or creates a fresh metavariable with that name.\n\nIn particular, the synthetic hole syntax creates \"synthetic opaque metavariables\",\nthe same kind of metavariable used to represent goals in the tactic state.\n\nSynthetic holes are similar to holes in that `_` also creates metavariables,\nbut synthetic opaque metavariables have some different properties:\n- In tactics such as `refine`, only synthetic holes yield new goals.\n- During elaboration, unification will not solve for synthetic opaque metavariables, they are \"opaque\".\n This is to prevent counterintuitive behavior such as disappearing goals.\n- When synthetic holes appear under binders, they capture local variables using a more complicated mechanism known as delayed assignment.\n\n## Delayed assigned metavariables\n\nThis section gives an overview of some technical details of synthetic holes, which you should feel free to skip.\nUnderstanding delayed assignments is mainly useful for those who are working on tactics and other metaprogramming.\nIt is included here until there is a suitable place for it in the reference manual.\n\nWhen a synthetic hole appears under a binding construct, such as for example `fun (x : α) (y : β) => ?s`,\nthe system creates a *delayed assignment*. This consists of\n1. A metavariable `?m` of type `(x : α) → (y : β) → γ x y` whose local context is the local context outside the `fun`,\n where `γ x y` is the type of `?s`. Recall that `x` and `y` appear in the local context of `?s`.\n2. A delayed assigment record associating `?m` to `?s` and the variables `#[x, y]` in the local context of `?s`\n\nThen, this function elaborates as `fun (x : α) (y : β) => ?m x y`, where one should understand `x` and `y` here\nas being De Bruijn indexes, since Lean uses the locally nameless encoding of lambda calculus.\n\nOnce `?s` is fully solved for, in the sense that after metavariable instantiation it is a metavariable-free term `e`,\nthen we can make the assignment `?m := fun (x' : α) (y' : β) => e[x := x', y := y']`.\n(Implementation note: Lean only instantiates full applications `?m x' y'` of delayed assigned metavariables, to skip forming this function.)\nThis delayed assignment mechanism is essential to the operation of basic tactics like `intro`,\nand a good mental model is that it is a way to \"apply\" the metavariable `?s` by substituting values in for some of its local variables.\nWhile it would be easier to immediately assign `?s := ?m x y`,\ndelayed assigment preserves `?s` as an unsolved-for metavariable with a local context that still contains `x` and `y`,\nwhich is exactly what tactics like `intro` need.\n\nBy default, delayed assigned metavariables pretty print with what they are delayed assigned to.\nThe delayed assigned metavariables themselves can be pretty printed using `set_option pp.mvars.delayed true`.\n\nFor more information, see the \"Gruesome details\" module docstrings in `Lean.MetavarContext`.\n",
|
||||
"kind": "markdown"}}
|
||||
{"textDocument": {"uri": "file:///issue5021.lean"},
|
||||
"position": {"line": 7, "character": 9}}
|
||||
|
|
@ -20,7 +20,7 @@
|
|||
{"start": {"line": 7, "character": 9}, "end": {"line": 7, "character": 12}},
|
||||
"contents":
|
||||
{"value":
|
||||
"```lean\nFalse\n```\n***\nParses a \"synthetic hole\", that is, `?foo` or `?_`.\nThis syntax is used to construct named metavariables. ",
|
||||
"```lean\nFalse\n```\n***\nA *synthetic hole* (or *synthetic placeholder*), which stands for an unknown term that should be synthesized using tactics.\n- `?_` creates a fresh metavariable with an auto-generated name.\n- `?m` either refers to a pre-existing metavariable named `m` or creates a fresh metavariable with that name.\n\nIn particular, the synthetic hole syntax creates \"synthetic opaque metavariables\",\nthe same kind of metavariable used to represent goals in the tactic state.\n\nSynthetic holes are similar to holes in that `_` also creates metavariables,\nbut synthetic opaque metavariables have some different properties:\n- In tactics such as `refine`, only synthetic holes yield new goals.\n- During elaboration, unification will not solve for synthetic opaque metavariables, they are \"opaque\".\n This is to prevent counterintuitive behavior such as disappearing goals.\n- When synthetic holes appear under binders, they capture local variables using a more complicated mechanism known as delayed assignment.\n\n## Delayed assigned metavariables\n\nThis section gives an overview of some technical details of synthetic holes, which you should feel free to skip.\nUnderstanding delayed assignments is mainly useful for those who are working on tactics and other metaprogramming.\nIt is included here until there is a suitable place for it in the reference manual.\n\nWhen a synthetic hole appears under a binding construct, such as for example `fun (x : α) (y : β) => ?s`,\nthe system creates a *delayed assignment*. This consists of\n1. A metavariable `?m` of type `(x : α) → (y : β) → γ x y` whose local context is the local context outside the `fun`,\n where `γ x y` is the type of `?s`. Recall that `x` and `y` appear in the local context of `?s`.\n2. A delayed assigment record associating `?m` to `?s` and the variables `#[x, y]` in the local context of `?s`\n\nThen, this function elaborates as `fun (x : α) (y : β) => ?m x y`, where one should understand `x` and `y` here\nas being De Bruijn indexes, since Lean uses the locally nameless encoding of lambda calculus.\n\nOnce `?s` is fully solved for, in the sense that after metavariable instantiation it is a metavariable-free term `e`,\nthen we can make the assignment `?m := fun (x' : α) (y' : β) => e[x := x', y := y']`.\n(Implementation note: Lean only instantiates full applications `?m x' y'` of delayed assigned metavariables, to skip forming this function.)\nThis delayed assignment mechanism is essential to the operation of basic tactics like `intro`,\nand a good mental model is that it is a way to \"apply\" the metavariable `?s` by substituting values in for some of its local variables.\nWhile it would be easier to immediately assign `?s := ?m x y`,\ndelayed assigment preserves `?s` as an unsolved-for metavariable with a local context that still contains `x` and `y`,\nwhich is exactly what tactics like `intro` need.\n\nBy default, delayed assigned metavariables pretty print with what they are delayed assigned to.\nThe delayed assigned metavariables themselves can be pretty printed using `set_option pp.mvars.delayed true`.\n\nFor more information, see the \"Gruesome details\" module docstrings in `Lean.MetavarContext`.\n",
|
||||
"kind": "markdown"}}
|
||||
{"textDocument": {"uri": "file:///issue5021.lean"},
|
||||
"position": {"line": 7, "character": 11}}
|
||||
|
|
@ -28,5 +28,5 @@
|
|||
{"start": {"line": 7, "character": 9}, "end": {"line": 7, "character": 12}},
|
||||
"contents":
|
||||
{"value":
|
||||
"```lean\nFalse\n```\n***\nParses a \"synthetic hole\", that is, `?foo` or `?_`.\nThis syntax is used to construct named metavariables. ",
|
||||
"```lean\nFalse\n```\n***\nA *synthetic hole* (or *synthetic placeholder*), which stands for an unknown term that should be synthesized using tactics.\n- `?_` creates a fresh metavariable with an auto-generated name.\n- `?m` either refers to a pre-existing metavariable named `m` or creates a fresh metavariable with that name.\n\nIn particular, the synthetic hole syntax creates \"synthetic opaque metavariables\",\nthe same kind of metavariable used to represent goals in the tactic state.\n\nSynthetic holes are similar to holes in that `_` also creates metavariables,\nbut synthetic opaque metavariables have some different properties:\n- In tactics such as `refine`, only synthetic holes yield new goals.\n- During elaboration, unification will not solve for synthetic opaque metavariables, they are \"opaque\".\n This is to prevent counterintuitive behavior such as disappearing goals.\n- When synthetic holes appear under binders, they capture local variables using a more complicated mechanism known as delayed assignment.\n\n## Delayed assigned metavariables\n\nThis section gives an overview of some technical details of synthetic holes, which you should feel free to skip.\nUnderstanding delayed assignments is mainly useful for those who are working on tactics and other metaprogramming.\nIt is included here until there is a suitable place for it in the reference manual.\n\nWhen a synthetic hole appears under a binding construct, such as for example `fun (x : α) (y : β) => ?s`,\nthe system creates a *delayed assignment*. This consists of\n1. A metavariable `?m` of type `(x : α) → (y : β) → γ x y` whose local context is the local context outside the `fun`,\n where `γ x y` is the type of `?s`. Recall that `x` and `y` appear in the local context of `?s`.\n2. A delayed assigment record associating `?m` to `?s` and the variables `#[x, y]` in the local context of `?s`\n\nThen, this function elaborates as `fun (x : α) (y : β) => ?m x y`, where one should understand `x` and `y` here\nas being De Bruijn indexes, since Lean uses the locally nameless encoding of lambda calculus.\n\nOnce `?s` is fully solved for, in the sense that after metavariable instantiation it is a metavariable-free term `e`,\nthen we can make the assignment `?m := fun (x' : α) (y' : β) => e[x := x', y := y']`.\n(Implementation note: Lean only instantiates full applications `?m x' y'` of delayed assigned metavariables, to skip forming this function.)\nThis delayed assignment mechanism is essential to the operation of basic tactics like `intro`,\nand a good mental model is that it is a way to \"apply\" the metavariable `?s` by substituting values in for some of its local variables.\nWhile it would be easier to immediately assign `?s := ?m x y`,\ndelayed assigment preserves `?s` as an unsolved-for metavariable with a local context that still contains `x` and `y`,\nwhich is exactly what tactics like `intro` need.\n\nBy default, delayed assigned metavariables pretty print with what they are delayed assigned to.\nThe delayed assigned metavariables themselves can be pretty printed using `set_option pp.mvars.delayed true`.\n\nFor more information, see the \"Gruesome details\" module docstrings in `Lean.MetavarContext`.\n",
|
||||
"kind": "markdown"}}
|
||||
|
|
|
|||
|
|
@ -21,7 +21,7 @@ constructor expected
|
|||
[false, true, true]
|
||||
match1.lean:136:7-136:22: error: invalid match-expression, type of pattern variable 'a' contains metavariables
|
||||
?m
|
||||
fun x => ?m x : ?m × ?m → ?m
|
||||
fun x => ?m : ?m × ?m → ?m
|
||||
fun x =>
|
||||
match x with
|
||||
| (a, b) => a + b : Nat × Nat → Nat
|
||||
|
|
|
|||
|
|
@ -1,5 +1,5 @@
|
|||
mulcommErrorMessage.lean:8:13-13:25: error: type mismatch
|
||||
fun a b => ?m a b
|
||||
fun a b => ?m
|
||||
has type
|
||||
(a : ?m) → (b : ?m a) → ?m a b : Sort (imax ?u ?u ?u)
|
||||
but is expected to have type
|
||||
|
|
@ -21,7 +21,7 @@ has type
|
|||
but is expected to have type
|
||||
false = true : Prop
|
||||
mulcommErrorMessage.lean:16:3-17:47: error: type mismatch
|
||||
fun a b => ?m a b
|
||||
fun a b => ?m
|
||||
has type
|
||||
(a : ?m) → (b : ?m a) → ?m a b : Sort (imax ?u ?u ?u)
|
||||
but is expected to have type
|
||||
|
|
|
|||
|
|
@ -9,10 +9,10 @@ but is expected to have type
|
|||
f ?x (sorryAx Bool true) : Nat
|
||||
g ?x ?x : Nat
|
||||
20
|
||||
foo (fun x => ?m x) ?hole : Nat
|
||||
foo (fun x => ?hole) ?hole : Nat
|
||||
bla ?hole fun x => ?hole : Nat
|
||||
namedHoles.lean:35:38-35:43: error: synthetic hole has already been defined with an incompatible local context
|
||||
boo (fun x => ?m x) fun y => sorryAx Nat true : Nat
|
||||
boo (fun x => ?hole) fun y => sorryAx Nat true : Nat
|
||||
11
|
||||
12
|
||||
namedHoles.lean:58:26-58:31: error: synthetic hole has already been defined and assigned to value incompatible with the current context
|
||||
|
|
|
|||
|
|
@ -18,7 +18,7 @@ case refine'_4
|
|||
⊢ ?refine'_1
|
||||
|
||||
case refine'_5
|
||||
⊢ ¬(fun x => ?m.17 x) ?refine'_3 = (fun x => ?m.17 x) ?refine'_4
|
||||
⊢ ¬(fun x => ?m.16) ?refine'_3 = (fun x => ?m.16) ?refine'_4
|
||||
-/
|
||||
#guard_msgs in
|
||||
example : False := by
|
||||
|
|
|
|||
|
|
@ -30,7 +30,7 @@ error: invalid constructor ⟨...⟩, expected type must be an inductive type
|
|||
info: let x1 := { n := 1 };
|
||||
let x2 := { n := 2 };
|
||||
let x3 := { n := 3 };
|
||||
let x4 := ?_ x1 x2 x3;
|
||||
let x4 := ?_;
|
||||
let x5 := { n := 5 };
|
||||
let x6 := { n := 6 };
|
||||
Foo.sum [x1, x2, x3, x5, x6] : Foo
|
||||
|
|
|
|||
|
|
@ -1,4 +1,4 @@
|
|||
fun x => ?m x
|
||||
fun x => ?m
|
||||
none
|
||||
(some (OfNat.ofNat.{0} Nat 0 (instOfNatNat 0)))
|
||||
0
|
||||
|
|
|
|||
Loading…
Add table
Reference in a new issue