fix: Let tactic not bringing binder into scope

Pantograph/Protocol.lean

@@ -51,7 +51,7 @@ structure Variable where
   /-- The name displayed to the user -/
   userName: String
   /-- Does the name contain a dagger -/
-  isInaccessible?: Option Bool := .none
+  isInaccessible?: Option Bool := .some false
   type?: Option Expression  := .none
   value?: Option Expression := .none
   deriving Lean.ToJson

Pantograph/Serial.lean

@@ -215,11 +215,13 @@ def serializeGoal (options: @&Protocol.Options) (goal: MVarId) (mvarDecl: Metava
         return {
           name := ofName fvarId.name,
           userName:= ofName userName.simpMacroScopes,
+          isInaccessible? := .some userName.isInaccessibleUserName
         }
       | .ldecl _ fvarId userName _ _ _ _ => do
         return {
           name := ofName fvarId.name,
           userName := toString userName.simpMacroScopes,
+          isInaccessible? := .some userName.isInaccessibleUserName
         }
     let ppVar (localDecl : LocalDecl) : MetaM Protocol.Variable := do
       match localDecl with

Pantograph/Tactic/Assign.lean

@@ -19,9 +19,12 @@ def assign (goal: MVarId) (expr: Expr): MetaM (List MVarId) := do
   nextGoals.toList.filterM (not <$> ·.isAssigned)
 
 def evalAssign : Elab.Tactic.Tactic := fun stx => Elab.Tactic.withMainContext do
-  let goalType ← Elab.Tactic.getMainTarget
-  let expr ← Elab.Term.elabTermAndSynthesize (stx := stx) (expectedType? := .some goalType)
-  let nextGoals ← assign (← Elab.Tactic.getMainGoal) expr
+  let target ← Elab.Tactic.getMainTarget
+  let (expr, nextGoals) ← Elab.Tactic.elabTermWithHoles stx
+    (expectedType? := .some target)
+    (tagSuffix := .anonymous )
+    (allowNaturalHoles := true)
+  (← Elab.Tactic.getMainGoal).assign expr
   Elab.Tactic.setGoals nextGoals
 
 

Pantograph/Tactic/Prograde.lean

@@ -64,13 +64,14 @@ def «let» (mvarId: MVarId) (binderName: Name) (type: Expr): MetaM BranchResult
   let lctx ← MonadLCtx.getLCtx
 
   -- The branch goal inherits the same context, but with a different type
-  let mvarBranch ← Meta.mkFreshExprMVarAt lctx (← Meta.getLocalInstances) type
+  let mvarBranch ← Meta.mkFreshExprMVarAt lctx (← Meta.getLocalInstances) type (userName := binderName)
 
   assert! ¬ type.hasLooseBVars
-  let upstreamType := .letE binderName type mvarBranch (← mvarId.getType) false
-  let mvarUpstream ← Meta.mkFreshExprMVarAt (← getLCtx) (← Meta.getLocalInstances)
-    upstreamType (kind := MetavarKind.synthetic) (userName := ← mvarId.getTag)
-  mvarId.assign mvarUpstream
+  let mvarUpstream ← Meta.withLetDecl binderName type mvarBranch $ λ fvar => do
+    let mvarUpstream ← Meta.mkFreshExprMVarAt (← getLCtx) (← Meta.getLocalInstances)
+      (type := ← mvarId.getType) (kind := MetavarKind.synthetic) (userName := ← mvarId.getTag)
+    mvarId.assign $ .letE binderName type fvar mvarUpstream (nonDep := false)
+    pure mvarUpstream
 
   return {
     main := mvarUpstream.mvarId!,

Test/Metavar.lean

@@ -198,15 +198,16 @@ def test_proposition_generation: TestM Unit := do
       addTest $ assertUnreachable $ other.toString
       return ()
   addTest $ LSpec.check ":= λ (x: Nat), _" ((← state2.serializeGoals (options := ← read)).map (·.target.pp?) =
-    #[.some "∀ (x : Nat), ?m.29 x"])
+    #[.some "?m.29 x"])
   addTest $ LSpec.test "(2 root)" state2.rootExpr?.isNone
 
-  let state3 ← match ← state2.tryAssign (goalId := 0) (expr := "fun x => Eq.refl x") with
+  let assign := "Eq.refl x"
+  let state3 ← match ← state2.tryAssign (goalId := 0) (expr := assign) with
     | .success state => pure state
     | other => do
       addTest $ assertUnreachable $ other.toString
       return ()
-  addTest $ LSpec.check ":= Eq.refl" ((← state3.serializeGoals (options := ← read)).map (·.target.pp?) =
+  addTest $ LSpec.check s!":= {assign}" ((← state3.serializeGoals (options := ← read)).map (·.target.pp?) =
     #[])
 
   addTest $ LSpec.test "(3 root)" state3.rootExpr?.isSome

Test/Proofs.lean

@@ -175,7 +175,7 @@ def test_delta_variable: TestM Unit := do
       vars := (nameType.map fun x => ({
         userName := x.fst,
         type? := x.snd.map (λ type => { pp? := type }),
-        isInaccessible? := x.snd.map (λ _ => false)
+        isInaccessible? := .some false,
       })).toArray
     }
 
@@ -544,83 +544,6 @@ def test_calc: TestM Unit := do
         ("h1", "a + b = b + c"), ("h2", "b + c = c + d")] ++ free
       buildGoal free target userName?
 
-def test_let (specialized: Bool): TestM Unit := do
-  let state? ← startProof (.expr "∀ (a: Nat) (p: Prop), p → p ∨ ¬p")
-  let state0 ← match state? with
-    | .some state => pure state
-    | .none => do
-      addTest $ assertUnreachable "Goal could not parse"
-      return ()
-  let tactic := "intro a p h"
-  let state1 ← match ← state0.tryTactic (goalId := 0) (tactic := tactic) with
-    | .success state => pure state
-    | other => do
-      addTest $ assertUnreachable $ other.toString
-      return ()
-  addTest $ LSpec.check tactic ((← state1.serializeGoals (options := ← read)).map (·.devolatilize) =
-    #[interiorGoal [] "p ∨ ¬p"])
-
-
-  let letType := "Nat"
-  let expr := s!"let b: {letType} := _; _"
-  let result2 ← match specialized with
-    | true => state1.tryLet (goalId := 0) (binderName := "b") (type := letType)
-    | false => state1.tryAssign (goalId := 0) (expr := expr)
-  let state2 ← match result2 with
-    | .success state => pure state
-    | other => do
-      addTest $ assertUnreachable $ other.toString
-      return ()
-  let serializedState2 ← state2.serializeGoals (options := ← read)
-  addTest $ LSpec.check expr (serializedState2.map (·.devolatilize) =
-    #[
-      interiorGoal [] letType,
-      interiorGoal [] "let b := ?m.20;\np ∨ ¬p"
-    ])
-  -- Check that the goal mvar ids match up
-  addTest $ LSpec.check "(mvarId)" ((serializedState2.map (·.name) |>.get! 0) = "_uniq.20")
-
-  let tactic := "exact a"
-  let state3 ← match ← state2.tryTactic (goalId := 0) (tactic := tactic) with
-    | .success state => pure state
-    | other => do
-      addTest $ assertUnreachable $ other.toString
-      return ()
-  addTest $ LSpec.check tactic ((← state3.serializeGoals (options := ← read)).map (·.devolatilize) = #[])
-
-  let state3r ← match state3.continue state2 with
-    | .error msg => do
-      addTest $ assertUnreachable $ msg
-      return ()
-    | .ok state => pure state
-  addTest $ LSpec.check "(continue)" ((← state3r.serializeGoals (options := ← read)).map (·.devolatilize) =
-    #[interiorGoal [] "let b := a;\np ∨ ¬p"])
-
-  let tactic := "exact h"
-  match ← state3r.tryTactic (goalId := 0) (tactic := tactic) with
-  | .failure #[message] =>
-    addTest $ LSpec.check tactic  (message = "type mismatch\n  h\nhas type\n  p : Prop\nbut is expected to have type\n  let b := a;\n  p ∨ ¬p : Prop")
-  | other => do
-    addTest $ assertUnreachable $ other.toString
-
-  let tactic := "intro b"
-  let state4 ← match ← state3r.tryTactic (goalId := 0) (tactic := tactic) with
-    | .success state => pure state
-    | other => do
-      addTest $ assertUnreachable $ other.toString
-      return ()
-  let tactic := "exact Or.inl h"
-  let state5 ← match ← state4.tryTactic (goalId := 0) (tactic := tactic) with
-    | .success state => pure state
-    | other => do
-      addTest $ assertUnreachable $ other.toString
-      return ()
-  addTest $ LSpec.test "(5 root)" state5.rootExpr?.isSome
-  where
-    interiorGoal (free: List (String × String)) (target: String) (userName?: Option String := .none) :=
-      let free := [("a", "Nat"), ("p", "Prop"), ("h", "p")] ++ free
-      buildGoal free target userName?
-
 def test_nat_zero_add: TestM Unit := do
   let state? ← startProof (.expr "∀ (n: Nat), n + 0 = n")
   let state0 ← match state? with
@@ -795,8 +718,6 @@ def suite (env: Environment): List (String × IO LSpec.TestSeq) :=
     ("Or.comm", test_or_comm),
     ("conv", test_conv),
     ("calc", test_calc),
-    ("let via assign", test_let false),
-    ("let via tryLet", test_let true),
     ("Nat.zero_add", test_nat_zero_add),
     ("Nat.zero_add alt", test_nat_zero_add_alt),
   ]

Test/Tactic/Prograde.lean

@@ -162,12 +162,105 @@ def test_proof_have : TestT Elab.TermElabM Unit := do
 
   addTest $ LSpec.check "(4 root)" state4.rootExpr?.isSome
 
+def test_let (specialized: Bool): TestT Elab.TermElabM Unit := do
+  let rootExpr ← parseSentence "∀ (p q: Prop), p → ((p ∨ q) ∨ (p ∨ q))"
+  let state0 ← GoalState.create rootExpr
+  let tactic := "intro a p h"
+  let state1 ← match ← state0.tryTactic (goalId := 0) (tactic := tactic) with
+    | .success state => pure state
+    | other => do
+      addTest $ assertUnreachable $ other.toString
+      return ()
+  addTest $ LSpec.check tactic ((← state1.serializeGoals).map (·.devolatilize) =
+    #[{
+      target := { pp? := .some mainTarget },
+      vars := interiorVars,
+    }])
+
+  let letType := "Nat"
+  let expr := s!"let b: {letType} := _; _"
+  let result2 ← match specialized with
+    | true => state1.tryLet (goalId := 0) (binderName := "b") (type := letType)
+    | false => state1.tryAssign (goalId := 0) (expr := expr)
+  let state2 ← match result2 with
+    | .success state => pure state
+    | other => do
+      addTest $ assertUnreachable $ other.toString
+      return ()
+  let serializedState2 ← state2.serializeGoals
+  let letBindName := if specialized then "b" else "_1"
+  addTest $ LSpec.check expr (serializedState2.map (·.devolatilize) =
+    #[{
+      target := { pp? := .some letType },
+      vars := interiorVars,
+      userName? := .some letBindName
+    },
+    {
+      target := { pp? := .some mainTarget },
+      vars := interiorVars ++ #[{
+        userName := "b",
+        type? := .some { pp? := .some letType },
+        value? := .some { pp? := .some s!"?{letBindName}" },
+      }],
+      userName? := if specialized then .none else .some "_2",
+    }
+    ])
+
+  let tactic := "exact 1"
+  let state3 ← match ← state2.tryTactic (goalId := 0) (tactic := tactic) with
+    | .success state => pure state
+    | other => do
+      addTest $ assertUnreachable $ other.toString
+      return ()
+  addTest $ LSpec.check tactic ((← state3.serializeGoals).map (·.devolatilize) = #[])
+
+  let state3r ← match state3.continue state2 with
+    | .error msg => do
+      addTest $ assertUnreachable $ msg
+      return ()
+    | .ok state => pure state
+  addTest $ LSpec.check "(continue)" ((← state3r.serializeGoals).map (·.devolatilize) =
+    #[
+    {
+      target := { pp? := .some mainTarget },
+      vars := interiorVars ++ #[{
+        userName := "b",
+        type? := .some { pp? := .some "Nat" },
+        value? := .some { pp? := .some "1" },
+      }],
+      userName? := if specialized then .none else .some "_2",
+    }
+    ])
+
+  let tactic := "exact h"
+  match ← state3r.tryTactic (goalId := 0) (tactic := tactic) with
+  | .failure #[message] =>
+    addTest $ LSpec.check tactic  (message = s!"type mismatch\n  h\nhas type\n  a : Prop\nbut is expected to have type\n  {mainTarget} : Prop")
+  | other => do
+    addTest $ assertUnreachable $ other.toString
+
+  let tactic := "exact Or.inl (Or.inl h)"
+  let state4 ← match ← state3r.tryTactic (goalId := 0) (tactic := tactic) with
+    | .success state => pure state
+    | other => do
+      addTest $ assertUnreachable $ other.toString
+      return ()
+  addTest $ LSpec.test "(4 root)" state4.rootExpr?.isSome
+  where
+    mainTarget := "(a ∨ p) ∨ a ∨ p"
+    interiorVars: Array Protocol.Variable := #[
+        { userName := "a", type? := .some { pp? := .some "Prop" }, },
+        { userName := "p", type? := .some { pp? := .some "Prop" }, },
+        { userName := "h", type? := .some { pp? := .some "a" }, }
+      ]
 
 def suite (env: Environment): List (String × IO LSpec.TestSeq) :=
   [
     ("eval", test_eval),
     ("Proof eval", test_proof_eval),
     ("Proof have", test_proof_have),
+    ("let via assign", test_let false),
+    ("let via tryLet", test_let true),
   ] |>.map (λ (name, t) => (name, runTestTermElabM env t))
 
 end Pantograph.Test.Tactic.Prograde