17581a2628
This PR adds `BackwardRule` for efficient goal transformation via backward chaining in `SymM`. `BackwardRule` stores a theorem expression, precomputed pattern for fast unification, and argument indices that become new subgoals. The subgoal ordering lists non-dependent goals first to match the behavior of `MetaM.apply`. `BackwardRule.apply` unifies the goal type with the rule's pattern, assigns the goal metavariable to the theorem application, and returns new subgoals for unassigned arguments.
51 lines
1.9 KiB
Text
51 lines
1.9 KiB
Text
import Lean.Meta.Sym
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open Lean Meta Sym Grind
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set_option grind.debug true
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opaque p : Nat → Prop
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opaque q : Nat → Nat → Prop
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axiom pax : p x
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def ex := ∃ x : Nat, p x ∧ x = .zero
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def test1 : SymM Unit := do
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let pEx ← mkPatternFromDecl ``Exists.intro
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let pAnd ← mkPatternFromDecl ``And.intro
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let pEq ← mkPatternFromDecl ``Eq.refl
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let e ← shareCommon (← getConstInfo ``ex).value!
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let some r₁ ← pEx.match? e | throwError "failed"
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logInfo <| mkAppN (mkConst ``Exists.intro r₁.us) r₁.args
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let some r₂ ← pAnd.match? (← inferType r₁.args[3]!) | throwError "failed"
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logInfo <| mkAppN (mkConst ``And.intro r₂.us) r₂.args
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let some r₃ ← pEq.unify? (← inferType r₂.args[3]!) | throwError "failed"
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logInfo <| mkAppN (mkConst ``Eq.refl r₃.us) r₃.args
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/--
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info: @Exists.intro Nat (fun x => And (p x) (@Eq Nat x Nat.zero)) ?m.1 ?m.2
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---
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info: @And.intro (p ?m.1) (@Eq Nat ?m.1 Nat.zero) ?m.3 ?m.4
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---
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info: @Eq.refl Nat Nat.zero
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-/
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#guard_msgs in
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set_option pp.explicit true in
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#eval SymM.run' test1
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def test2 : SymM Unit := do
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let ruleEx ← mkBackwardRuleFromDecl ``Exists.intro
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let ruleAnd ← mkBackwardRuleFromDecl ``And.intro
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let ruleRefl ← mkBackwardRuleFromDecl ``Eq.refl
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let rulePax ← mkBackwardRuleFromDecl ``pax
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let mvar ← mkFreshExprMVar (← getConstInfo ``ex).value!
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let goal ← Sym.mkGoal mvar.mvarId!
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let [goal, _] ← ruleEx.apply goal | throwError "Failed"
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let [goal₁, goal₂] ← ruleAnd.apply goal | throwError "Failed"
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let [] ← rulePax.apply goal₁ | throwError "Failed"
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let [] ← ruleRefl.apply goal₂ | throwError "Failed"
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logInfo mvar
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/--
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info: @Exists.intro Nat (fun x => And (p x) (@Eq Nat x Nat.zero)) Nat.zero
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(@And.intro (p Nat.zero) (@Eq Nat Nat.zero Nat.zero) (@pax Nat.zero) (@Eq.refl Nat Nat.zero))
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-/
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#guard_msgs in
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set_option pp.explicit true in
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#eval SymM.run' test2
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