feat: Assigning a goal with an expression

Pantograph/Goal.lean

@@ -47,13 +47,15 @@ protected def GoalState.runM {α: Type} (state: GoalState) (m: Elab.TermElabM α
 
 protected def GoalState.mctx (state: GoalState): MetavarContext :=
   state.savedState.term.meta.meta.mctx
+protected def GoalState.env (state: GoalState): Environment :=
+  state.savedState.term.meta.core.env
 private def GoalState.mvars (state: GoalState): SSet MVarId :=
   state.mctx.decls.foldl (init := .empty) fun acc k _ => acc.insert k
 
 /-- Inner function for executing tactic on goal state -/
 def executeTactic (state: Elab.Tactic.SavedState) (goal: MVarId) (tactic: Syntax) :
-    M (Except (Array String) (Elab.Tactic.SavedState × List MVarId)):= do
-  let tacticM (stx: Syntax):  Elab.Tactic.TacticM (Except (Array String) (Elab.Tactic.SavedState × List MVarId)) := do
+    M (Except (Array String) Elab.Tactic.SavedState):= do
+  let tacticM (stx: Syntax):  Elab.Tactic.TacticM (Except (Array String) Elab.Tactic.SavedState) := do
     state.restore
     Elab.Tactic.setGoals [goal]
     try
@@ -63,9 +65,7 @@ def executeTactic (state: Elab.Tactic.SavedState) (goal: MVarId) (tactic: Syntax
         let errors ← (messages.map Message.data).mapM fun md => md.toString
         return .error errors
       else
-        let unsolved ← Elab.Tactic.getUnsolvedGoals
-        -- The order of evaluation is important here, since `getUnsolvedGoals` prunes the goals set
-        return .ok (← MonadBacktrack.saveState, unsolved)
+        return .ok (← MonadBacktrack.saveState)
     catch exception =>
       return .error #[← exception.toMessageData.toString]
   tacticM tactic { elaborator := .anonymous } |>.run' state.tactic
@@ -97,8 +97,7 @@ protected def GoalState.execute (state: GoalState) (goalId: Nat) (tactic: String
   match (← executeTactic (state := state.savedState) (goal := goal) (tactic := tactic)) with
   | .error errors =>
     return .failure errors
-  | .ok (nextSavedState, nextGoals) =>
-    assert! nextSavedState.tactic.goals.length == nextGoals.length
+  | .ok nextSavedState =>
     -- Assert that the definition of metavariables are the same
     let nextMCtx := nextSavedState.term.meta.meta.mctx
     let prevMCtx := state.savedState.term.meta.meta.mctx
@@ -112,12 +111,64 @@ protected def GoalState.execute (state: GoalState) (goalId: Nat) (tactic: String
         return acc.insert mvarId
       ) SSet.empty
     return .success {
+      state with
       savedState := nextSavedState
-      root := state.root,
       newMVars,
       parentGoalId := goalId,
     }
 
+protected def GoalState.tryAssign (state: GoalState) (goalId: Nat) (expr: String): M TacticResult := do
+  let goal ← match state.savedState.tactic.goals.get? goalId with
+    | .some goal => pure goal
+    | .none => return .indexError goalId
+  let expr ← match Parser.runParserCategory
+    (env := state.env)
+    (catName := `term)
+    (input := expr)
+    (fileName := "<stdin>") with
+    | .ok syn => pure syn
+    | .error error => return .parseError error
+  let tacticM:  Elab.Tactic.TacticM TacticResult := do
+    state.savedState.restore
+    Elab.Tactic.setGoals [goal]
+    try
+      let expr ← Elab.Term.elabTerm (stx := expr) (expectedType? := .none)
+      -- Attempt to unify the expression
+      let goalType ← goal.getType
+      let exprType ← Meta.inferType expr
+      if !(← Meta.isDefEq goalType exprType) then
+        return .failure #["Type unification failed", toString (← Meta.ppExpr goalType), toString (← Meta.ppExpr exprType)]
+      goal.checkNotAssigned `GoalState.tryAssign
+      goal.assign expr
+      if (← getThe Core.State).messages.hasErrors then
+        let messages := (← getThe Core.State).messages.getErrorMessages |>.toList.toArray
+        let errors ← (messages.map Message.data).mapM fun md => md.toString
+        return .failure errors
+      else
+        let prevMCtx := state.savedState.term.meta.meta.mctx
+        let nextMCtx ← getMCtx
+        -- Generate a list of mvarIds that exist in the parent state; Also test the
+        -- assertion that the types have not changed on any mvars.
+        let newMVars ← nextMCtx.decls.foldlM (fun acc mvarId mvarDecl => do
+          if let .some prevMVarDecl := prevMCtx.decls.find? mvarId then
+            assert! prevMVarDecl.type == mvarDecl.type
+            return acc
+          else
+            return mvarId :: acc
+          ) []
+        -- The new goals are the newMVars that lack an assignment
+        Elab.Tactic.setGoals (← newMVars.filterM (λ mvar => do pure !(← mvar.isAssigned)))
+        let nextSavedState ← MonadBacktrack.saveState
+        return .success {
+          state with
+          savedState := nextSavedState,
+          newMVars := newMVars.toSSet,
+          parentGoalId := goalId,
+        }
+    catch exception =>
+      return .failure #[← exception.toMessageData.toString]
+  tacticM { elaborator := .anonymous } |>.run' state.savedState.tactic
+
 /-- After finishing one branch of a proof (`graftee`), pick up from the point where the proof was left off (`target`) -/
 protected def GoalState.continue (target: GoalState) (graftee: GoalState): Except String GoalState :=
   if target.root != graftee.root then

Pantograph/Protocol.lean

@@ -172,7 +172,8 @@ structure GoalPrint where
   printContext: Bool := true
   printValue: Bool := true
   printNewMVars: Bool := false
-  printNonVisible: Bool := false
+  -- Print all mvars
+  printAll: Bool := false
 
 
 end Pantograph.Protocol

Pantograph/Serial.lean

@@ -262,9 +262,6 @@ protected def GoalState.serializeGoals (state: GoalState) (parent: Option GoalSt
     let parentGoal := parentState.goals.get! state.parentGoalId
     parentState.mctx.findDecl? parentGoal)
   goals.mapM fun goal => do
-    if options.noRepeat then
-      let key := if parentDecl?.isSome then "is some" else "is none"
-      IO.println s!"goal: {goal.name}, {key}"
     match state.mctx.findDecl? goal with
     | .some mvarDecl =>
       let serializedGoal ← serialize_goal options mvarDecl (parentDecl? := parentDecl?)
@@ -296,7 +293,7 @@ protected def GoalState.print (goalState: GoalState) (options: Protocol.GoalPrin
     else if mvarId == goalState.root then
       printMVar (pref := ">") mvarId decl
     -- Print the remainig ones that users don't see in Lean
-    else if options.printNonVisible then
+    else if options.printAll then
       let pref := if goalState.newMVars.contains mvarId then "~" else " "
       printMVar pref mvarId decl
     else

Test/Proofs.lean

@@ -66,8 +66,9 @@ def startProof (start: Start): TestM (Option GoalState) := do
 
 def assertUnreachable (message: String): LSpec.TestSeq := LSpec.check message false
 
-def buildGoal (nameType: List (String × String)) (target: String): Protocol.Goal :=
+def buildGoal (nameType: List (String × String)) (target: String) (caseName?: Option String := .none): Protocol.Goal :=
   {
+    caseName?,
     target := { pp? := .some target},
     vars := (nameType.map fun x => ({
       userName := x.fst,
@@ -187,21 +188,21 @@ def proof_arith: TestM Unit := do
       addTest $ assertUnreachable $ other.toString
       return ()
   addTest $ LSpec.check "intros" (state1.goals.length = 1)
-  addTest $ LSpec.test "1 root" state1.rootExpr.isNone
+  addTest $ LSpec.test "(1 root)" state1.rootExpr.isNone
   let state2 ← match ← state1.execute (goalId := 0) (tactic := "simp [Nat.add_assoc, Nat.add_comm, Nat.add_left_comm, Nat.mul_comm, Nat.mul_assoc, Nat.mul_left_comm] at *") with
     | .success state => pure state
     | other => do
       addTest $ assertUnreachable $ other.toString
       return ()
   addTest $ LSpec.check "simp ..." (state2.goals.length = 1)
-  addTest $ LSpec.check "2 root" state2.rootExpr.isNone
+  addTest $ LSpec.check "(2 root)" state2.rootExpr.isNone
   let state3 ← match ← state2.execute (goalId := 0) (tactic := "assumption") with
     | .success state => pure state
     | other => do
       addTest $ assertUnreachable $ other.toString
       return ()
   addTest $ LSpec.test "assumption" state3.goals.isEmpty
-  addTest $ LSpec.check "3 root" state3.rootExpr.isSome
+  addTest $ LSpec.check "(3 root)" state3.rootExpr.isSome
   return ()
 
 -- Two ways to write the same theorem
@@ -253,7 +254,7 @@ def proof_or_comm: TestM Unit := do
     | other => do
       addTest $ assertUnreachable $ other.toString
       return ()
-  addTest $ LSpec.check "· assumption" state4_1.goals.isEmpty
+  addTest $ LSpec.check "  assumption" state4_1.goals.isEmpty
   addTest $ LSpec.check "(4_1 root)" state4_1.rootExpr.isNone
   let state3_2 ← match ← state2.execute (goalId := 1) (tactic := "apply Or.inl") with
     | .success state => pure state
@@ -266,7 +267,7 @@ def proof_or_comm: TestM Unit := do
     | other => do
       addTest $ assertUnreachable $ other.toString
       return ()
-  addTest $ LSpec.check "· assumption" state4_2.goals.isEmpty
+  addTest $ LSpec.check "  assumption" state4_2.goals.isEmpty
   addTest $ LSpec.check "(4_2 root)" state4_2.rootExpr.isNone
   -- Ensure the proof can continue from `state4_2`.
   let state2b ← match state2.continue state4_2 with
@@ -286,8 +287,8 @@ def proof_or_comm: TestM Unit := do
     | other => do
       addTest $ assertUnreachable $ other.toString
       return ()
-  addTest $ LSpec.check "· assumption" state4_1.goals.isEmpty
-  addTest $ LSpec.check "4_1 root" state4_1.rootExpr.isSome
+  addTest $ LSpec.check "  assumption" state4_1.goals.isEmpty
+  addTest $ LSpec.check "(4_1 root)" state4_1.rootExpr.isSome
 
   return ()
   where
@@ -336,7 +337,45 @@ def proof_m_couple: TestM Unit := do
   addTest $ LSpec.test "(2 root)" state1b.rootExpr.isNone
   return ()
 
-/-- Tests the most basic form of proofs whose goals do not relate to each other -/
+def proof_proposition_generation: TestM Unit := do
+  let state? ← startProof (.expr "Σ' p:Prop, p")
+  let state0 ← match state? with
+    | .some state => pure state
+    | .none => do
+      addTest $ assertUnreachable "Goal could not parse"
+      return ()
+
+  let state1 ← match ← state0.execute (goalId := 0) (tactic := "apply PSigma.mk") with
+    | .success state => pure state
+    | other => do
+      addTest $ assertUnreachable $ other.toString
+      return ()
+  addTest $ LSpec.check "apply PSigma.mk" ((← state1.serializeGoals (options := ← read)).map (·.devolatilize) =
+    #[
+      buildGoal [] "?fst" (caseName? := .some "snd"),
+      buildGoal [] "Prop" (caseName? := .some "fst")
+      ])
+  addTest $ LSpec.test "(1 root)" state1.rootExpr.isNone
+
+  let state2 ← match ← state1.tryAssign (goalId := 0) (expr := "λ (x: Nat) => _") with
+    | .success state => pure state
+    | other => do
+      addTest $ assertUnreachable $ other.toString
+      return ()
+  addTest $ LSpec.check ":= λ (x: Nat), _" ((← state2.serializeGoals (options := ← read)).map (·.target.pp?) =
+    #[.some "Nat → Prop", .some "∀ (x : Nat), ?m.29 x"])
+  addTest $ LSpec.test "(2 root)" state2.rootExpr.isNone
+
+  let state3 ← match ← state2.tryAssign (goalId := 1) (expr := "fun x => Eq.refl x") 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.test "(3 root)" state3.rootExpr.isSome
+  return ()
+
 def suite: IO LSpec.TestSeq := do
   let env: Lean.Environment ← Lean.importModules
     (imports := #[{ module := Name.append .anonymous "Init", runtimeOnly := false}])
@@ -348,8 +387,8 @@ def suite: IO LSpec.TestSeq := do
     ("Nat.add_comm delta", proof_delta_variable),
     ("arithmetic", proof_arith),
     ("Or.comm", proof_or_comm),
-    ("2 < 5", proof_m_couple)
-    --("delta variable", proof_delta_variable)
+    ("2 < 5", proof_m_couple),
+    ("Proposition Generation", proof_proposition_generation)
   ]
   let tests ← tests.foldlM (fun acc tests => do
     let (name, tests) := tests