e574c5373f
Use zeta reduction to create new opportunities of beta-reduction. This issue fixes on the problems that were affecting the generation of equation theorems for `Array.heapSort.loop` (see issue: #998). After this fix, the equation theorem generation fails at `splitMatch`.
37 lines
1.5 KiB
Text
37 lines
1.5 KiB
Text
/-
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Copyright (c) 2020 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.Transform
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import Lean.Meta.Tactic.Replace
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namespace Lean.Meta
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def delta? (e : Expr) (p : Name → Bool := fun _ => true) : CoreM (Option Expr) :=
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matchConst e.getAppFn (fun _ => return none) fun fInfo fLvls => do
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if p fInfo.name && fInfo.hasValue && fInfo.levelParams.length == fLvls.length then
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let f := fInfo.instantiateValueLevelParams fLvls
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return some (f.betaRev e.getAppRevArgs (useZeta := true))
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else
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return none
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/- Low-level delta expansion. It is used to implement equation lemmas and elimination principles for recursive definitions. -/
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def deltaExpand (e : Expr) (p : Name → Bool) : CoreM Expr :=
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Core.transform e fun e => do
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match (← delta? e p) with
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| some e' => return TransformStep.visit e'
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| none => return TransformStep.visit e
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def deltaTarget (mvarId : MVarId) (p : Name → Bool) : MetaM MVarId :=
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withMVarContext mvarId do
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checkNotAssigned mvarId `delta
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change mvarId (← deltaExpand (← getMVarType mvarId) p) (checkDefEq := false)
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def deltaLocalDecl (mvarId : MVarId) (fvarId : FVarId) (p : Name → Bool) : MetaM MVarId :=
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withMVarContext mvarId do
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checkNotAssigned mvarId `delta
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let localDecl ← getLocalDecl fvarId
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changeLocalDecl mvarId fvarId (← deltaExpand (← getMVarType mvarId) p) (checkDefEq := false)
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end Lean.Meta
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