structure Lean.Meta.UnifyEqResult : Type

• mvarId : Lean.MVarId
• subst : Lean.Meta.FVarSubst
• numNewEqs : Nat

def Lean.Meta.unifyEq? (mvarId : Lean.MVarId) (eqFVarId : Lean.FVarId) (subst : optParam Lean.Meta.FVarSubst { map := ∅ }) (acyclic : optParam (Lean.MVarId → Lean.Expr → Lean.MetaM Bool) fun x x => pure false) (caseName? : optParam (Option Lake.Name) none) : Lean.MetaM (Option Lean.Meta.UnifyEqResult)

Helper method for methods such as Cases.unifyEqs?. Given the given goal mvarId containing the local hypothesis eqFVarId, it performs the following operations:

• If eqFVarId is a heterogeneous equality, tries to convert it to a homogeneous one.
• If eqFVarId is a homogeneous equality of the form a = b, it tries
  • If a and b are definitionally equal, clear it
  • Normalize a and b using the current reducibility setting.
  • If a (b) is a free variable not occurring in b (a), replace it everywhere.
  • If a and b are distinct constructors, return none to indicate that the goal has been closed.
  • If a and b are the same contructor, apply injection, the result contains the number of new equalities introduced in the goal.
  • It also tries to apply the given acyclic method to try to close the goal. Remark: It is a parameter because simp uses unifyEq?, and acyclic depends on simp.

def Lean.Meta.unifyEq?.substEq (mvarId : Lean.MVarId) (eqFVarId : Lean.FVarId) (subst : optParam Lean.Meta.FVarSubst { map := ∅ }) (acyclic : optParam (Lean.MVarId → Lean.Expr → Lean.MetaM Bool) fun x x => pure false) (eqDecl : Lean.LocalDecl) (a : Lean.Expr) (b : Lean.Expr) (symm : Bool) : Lean.MetaM (Option Lean.Meta.UnifyEqResult)

def Lean.Meta.unifyEq?.injection (mvarId : Lean.MVarId) (eqFVarId : Lean.FVarId) (subst : optParam Lean.Meta.FVarSubst { map := ∅ }) (caseName? : optParam (Option Lake.Name) none) (eqDecl : Lean.LocalDecl) (a : Lean.Expr) (b : Lean.Expr) : Lean.MetaM (Option Lean.Meta.UnifyEqResult)