32 lines
1 KiB
Text
32 lines
1 KiB
Text
/-
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Copyright (c) 2019 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Authors: Leonardo de Moura
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-/
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import Lean.Meta.ExprDefEq
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import Lean.Meta.Tactic.Util
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namespace Lean.Meta
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/-- Return a local declaration whose type is definitionally equal to `type`. -/
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def findLocalDeclWithType? (type : Expr) : MetaM (Option FVarId) := do
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(← getLCtx).findDeclRevM? fun localDecl => do
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if localDecl.isAuxDecl then
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return none
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else if (← isDefEq type localDecl.type) then
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return some localDecl.fvarId
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else
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return none
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def assumptionCore (mvarId : MVarId) : MetaM Bool :=
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withMVarContext mvarId do
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checkNotAssigned mvarId `assumption
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match (← findLocalDeclWithType? (← getMVarType mvarId)) with
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| none => return false
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| some fvarId => assignExprMVar mvarId (mkFVar fvarId); return true
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def assumption (mvarId : MVarId) : MetaM Unit :=
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unless (← assumptionCore mvarId) do
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throwTacticEx `assumption mvarId ""
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end Lean.Meta
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