def Lean.Meta.Match.mkNamedPattern (x h p : Expr) : MetaM Expr

def Lean.Meta.Match.isNamedPattern (e : Expr) : Bool

def Lean.Meta.Match.isNamedPattern? (e : Expr) : Option Expr

inductive Lean.Meta.Match.Pattern : Type

• inaccessible (e : Expr) : Pattern
• var (fvarId : FVarId) : Pattern
• ctor (ctorName : Name) (us : List Level) (params : List Expr) (fields : List Pattern) : Pattern
• val (e : Expr) : Pattern
• arrayLit (type : Expr) (xs : List Pattern) : Pattern
• as (varId : FVarId) (p : Pattern) (hId : FVarId) : Pattern

instance Lean.Meta.Match.instInhabitedPattern : Inhabited Pattern

partial def Lean.Meta.Match.Pattern.toMessageData : Pattern → MessageData

def Lean.Meta.Match.Pattern.toExpr (p : Pattern) (annotate : Bool := false) : MetaM Expr

partial def Lean.Meta.Match.Pattern.toExpr.visit (annotate : Bool := false) (p : Pattern) : MetaM Expr

partial def Lean.Meta.Match.Pattern.applyFVarSubst (s : FVarSubst) : Pattern → Pattern

Apply the free variable substitution s to the given pattern

def Lean.Meta.Match.Pattern.replaceFVarId (fvarId : FVarId) (v : Expr) (p : Pattern) : Pattern

partial def Lean.Meta.Match.Pattern.hasExprMVar : Pattern → Bool

partial def Lean.Meta.Match.Pattern.collectFVars (p : Pattern) : StateRefT' IO.RealWorld CollectFVars.State MetaM Unit

partial def Lean.Meta.Match.instantiatePatternMVars : Pattern → MetaM Pattern

structure Lean.Meta.Match.AltLHS : Type

• ref : Syntax
• fvarDecls : List LocalDecl
• patterns : List Pattern

def Lean.Meta.Match.AltLHS.collectFVars (altLHS : AltLHS) : StateRefT' IO.RealWorld CollectFVars.State MetaM Unit

def Lean.Meta.Match.instantiateAltLHSMVars (altLHS : AltLHS) : MetaM AltLHS

structure Lean.Meta.Match.Alt : Type

Match alternative

• ref : Syntax

  Syntax object for providing position information

• idx : Nat

  Original alternative index. Alternatives can be split, this index is the original position of the alternative that generated this one.

• rhs : Expr

  Right-hand-side of the alternative.

• fvarDecls : List LocalDecl

  Alternative pattern variables.

• patterns : List Pattern

  Alternative patterns.

• cnstrs : List (Expr × Expr)

  Pending constraints lhs ≋ rhs that need to be solved before the alternative is considered acceptable. We generate them when processing inaccessible patterns. Note that lhs and rhs often have different types. After we perform additional case analysis, their types become definitionally equal.

instance Lean.Meta.Match.instInhabitedAlt : Inhabited Alt

def Lean.Meta.Match.Alt.toMessageData (alt : Alt) : MetaM MessageData

def Lean.Meta.Match.Alt.applyFVarSubst (s : FVarSubst) (alt : Alt) : Alt

def Lean.Meta.Match.Alt.replaceFVarId (fvarId : FVarId) (v : Expr) (alt : Alt) : Alt

def Lean.Meta.Match.Alt.isLocalDecl (fvarId : FVarId) (alt : Alt) : Bool

Return true if fvarId is one of the alternative pattern variables

def Lean.Meta.Match.Alt.checkAndReplaceFVarId (fvarId : FVarId) (v : Expr) (alt : Alt) : MetaM Alt

Similar to checkAndReplaceFVarId, but ensures type of v is definitionally equal to type of fvarId. This extra check is necessary when performing dependent elimination and inaccessible terms have been used. For example, consider the following code fragment:

inductive Vec (α : Type u) : Nat → Type u where
  | nil : Vec α 0
  | cons {n} (head : α) (tail : Vec α n) : Vec α (n+1)

inductive VecPred {α : Type u} (P : α → Prop) : {n : Nat} → Vec α n → Prop where
  | nil   : VecPred P Vec.nil
  | cons  {n : Nat} {head : α} {tail : Vec α n} : P head → VecPred P tail → VecPred P (Vec.cons head tail)

theorem ex {α : Type u} (P : α → Prop) : {n : Nat} → (v : Vec α (n+1)) → VecPred P v → Exists P
  | _, Vec.cons head _, VecPred.cons h (w : VecPred P Vec.nil) => ⟨head, h⟩

Recall that _ in a pattern can be elaborated into pattern variable or an inaccessible term. The elaborator uses an inaccessible term when typing constraints restrict its value. Thus, in the example above, the _ at Vec.cons head _ becomes the inaccessible pattern .(Vec.nil) because the type ascription (w : VecPred P Vec.nil) propagates typing constraints that restrict its value to be Vec.nil. After elaboration the alternative becomes:

  | .(0), @Vec.cons .(α) .(0) head .(Vec.nil), @VecPred.cons .(α) .(P) .(0) .(head) .(Vec.nil) h w => ⟨head, h⟩

where

(head : α), (h: P head), (w : VecPred P Vec.nil)

Then, when we process this alternative in this module, the following check will detect that w has type VecPred P Vec.nil, when it is supposed to have type VecPred P tail. Note that if we had written

theorem ex {α : Type u} (P : α → Prop) : {n : Nat} → (v : Vec α (n+1)) → VecPred P v → Exists P
  | _, Vec.cons head Vec.nil, VecPred.cons h (w : VecPred P Vec.nil) => ⟨head, h⟩

we would get the easier to digest error message

missing cases:
_, (Vec.cons _ _ (Vec.cons _ _ _)), _

inductive Lean.Meta.Match.Example : Type

• var : FVarId → Example
• underscore : Example
• ctor : Name → List Example → Example
• val : Expr → Example
• arrayLit : List Example → Example

partial def Lean.Meta.Match.Example.replaceFVarId (fvarId : FVarId) (ex : Example) : Example → Example

partial def Lean.Meta.Match.Example.applyFVarSubst (s : FVarSubst) : Example → Example

partial def Lean.Meta.Match.Example.varsToUnderscore : Example → Example

partial def Lean.Meta.Match.Example.toMessageData : Example → MessageData

def Lean.Meta.Match.examplesToMessageData (cex : List Example) : MessageData

structure Lean.Meta.Match.Problem : Type

• mvarId : MVarId
• vars : List Expr
• alts : List Alt
• examples : List Example

instance Lean.Meta.Match.instInhabitedProblem : Inhabited Problem

def Lean.Meta.Match.withGoalOf {α : Type} (p : Problem) (x : MetaM α) : MetaM α

def Lean.Meta.Match.Problem.toMessageData (p : Problem) : MetaM MessageData

@[reducible, inline]

abbrev Lean.Meta.Match.CounterExample : Type

def Lean.Meta.Match.counterExampleToMessageData (cex : CounterExample) : MessageData

def Lean.Meta.Match.counterExamplesToMessageData (cexs : List CounterExample) : MessageData

structure Lean.Meta.Match.MatcherResult : Type

• matcher : Expr
• counterExamples : List CounterExample
• unusedAltIdxs : List Nat
• addMatcher : MetaM Unit

partial def Lean.Meta.Match.toPattern (e : Expr) : MetaM Pattern

Convert a expression occurring as the argument of a match motive application back into a Pattern For example, we can use this method to convert x::y::xs at

...
(motive : List Nat → Sort u_1) (xs : List Nat) (h_1 : (x y : Nat) → (xs : List Nat) → motive (x :: y :: xs))
...

into a pattern object