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.
37 lines
928 B
Text
37 lines
928 B
Text
import Lean
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macro "gen_term" n:num : term => do
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let mut stx ← `(True)
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for _ in 0...n.getNat do
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stx := ← `(let z : Nat := x + y; let y := y + 1; have : y >= 0 := Nat.zero_le y; forall x : Nat, $stx)
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`(let z : Nat := 0 ; forall x : Nat, forall y : Nat, $stx)
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open Lean Meta Sym Elab Tactic
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def test (mvarId : MVarId) : MetaM MVarId := do
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SymM.run do
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let (_, mvarId) ← intros mvarId
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return mvarId
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/--
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trace: z✝² : Nat := 0
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x✝² y✝² : Nat
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z✝¹ : Nat := x✝² + y✝²
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y✝¹ : Nat := y✝² + 1
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this✝¹ : y✝¹ ≥ 0 := Nat.zero_le y✝¹
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x✝¹ : Nat
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z✝ : Nat := x✝¹ + y✝¹
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y✝ : Nat := y✝¹ + 1
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this✝ : y✝ ≥ 0 := Nat.zero_le y✝
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x✝ : Nat
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⊢ True
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-/
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#guard_msgs in
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example : gen_term 2 := by
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run_tac liftMetaTactic1 fun mvarId => test mvarId
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trace_state
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constructor
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example : gen_term 70 := by
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run_tac liftMetaTactic1 fun mvarId => test mvarId
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constructor
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