32 lines
1.0 KiB
Plaintext
32 lines
1.0 KiB
Plaintext
import Lean
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open Lean
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namespace Pantograph.Tactic
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def assign (goal: MVarId) (expr: Expr): MetaM (List MVarId) := do
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goal.checkNotAssigned `Pantograph.Tactic.assign
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-- This run of the unifier is critical in resolving mvars in passing
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let exprType ← Meta.inferType expr
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let goalType ← goal.getType
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unless ← Meta.isDefEq goalType exprType do
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throwError s!"{← Meta.ppExpr expr} : {← Meta.ppExpr exprType} ≠ {← Meta.ppExpr goalType}"
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-- FIXME: Use `withCollectingNewGoalsFrom`. Think about how this interacts with elaboration ...
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let nextGoals ← Meta.getMVarsNoDelayed expr
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goal.assign expr
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nextGoals.toList.filterM (not <$> ·.isAssigned)
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def evalAssign : Elab.Tactic.Tactic := fun stx => Elab.Tactic.withMainContext do
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let target ← Elab.Tactic.getMainTarget
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let (expr, nextGoals) ← Elab.Tactic.elabTermWithHoles stx
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(expectedType? := .some target)
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(tagSuffix := .anonymous )
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(allowNaturalHoles := true)
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(← Elab.Tactic.getMainGoal).assign expr
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Elab.Tactic.setGoals nextGoals
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end Pantograph.Tactic
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