175661b6c3
This PR reorganizes the monad hierarchy for symbolic computation in Lean. ## Motivation We want a clean layering where: 1. A foundational monad (`SymM`) provides maximally shared terms and structural/syntactic `isDefEq` 2. `GrindM` builds on this foundation, adding E-graphs, congruence closure, and decision procedures 3. Symbolic execution / VCGen uses `GrindM` directly without introducing a third monad ## Changes The core symbolic computation layer still lives in `Lean.Meta.Sym`. This monad (`SymM`) provides: - Maximally shared terms with pointer-based equality - Structural/syntactic `isDefEq` and matching (no reduction, predictable cost) - Monotonic local contexts (no `revert` or `clear`), enabling O(1) metavariable validation - Efficient `intro`, `apply`, and `simp` implementations The name "Sym" reflects that this is infrastructure for symbolic computation: symbolic simulation, verification condition generation, and decision procedures. ### Updated hierarchy ``` Lean.Meta.Sym -- SymM: shared terms, syntactic isDefEq, intro, apply, simp Lean.Meta.Grind -- GrindM: E-graphs, congruence closure (extends SymM) ``` Symbolic execution is a usage pattern of `GrindM` operating on `Grind.Goal`, not a separate monad. This keeps the API surface minimal: users learn two monads, and VCGen is "how you use `GrindM`" (for users that want to use `grind`) rather than a third abstraction to understand.
23 lines
845 B
Text
23 lines
845 B
Text
import Lean.Meta.Sym
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open Lean Meta Sym Internal
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set_option grind.debug true
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def test : SymM Unit := do
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let f ← mkConstS `f
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let f₁ := mkConst `f
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let f₂ ← mkConstS `f
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assert! isSameExpr f f₂
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assert! !isSameExpr f f₁
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let x₁ ← mkBVarS 0
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let x₂ ← mkBVarS 0
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assert! isSameExpr
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(← mkLambdaS `x .default (← mkConstS ``Nat) (← mkMDataS {} (← mkProjS ``Prod 0 (← mkAppS f x₁))))
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(← mkLambdaS `y .default (← mkConstS ``Nat) (← mkMDataS {} (← mkProjS ``Prod 0 (← mkAppS f₂ x₂))))
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assert! !isSameExpr (← mkAppS f x₁) (mkApp f x₁)
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assert!
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mkLambda `x .default (mkConst ``Nat) (mkMData {} (mkProj ``Prod 0 (mkApp f x₁)))
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==
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(← mkLambdaS `y .default (← mkConstS ``Nat) (← mkMDataS {} (← mkProjS ``Prod 0 (← mkAppS f₂ x₂))))
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#eval SymM.run do
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test
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