6 changed files with 105 additions and 82 deletions
--- a/Pantograph/Delate.lean
+++ b/Pantograph/Delate.lean
@ -37,7 +37,7 @@ def analyzeProjection (env: Environment) (e: Expr): Projection :=
 def anonymousLevel : Level := .mvar ⟨.anonymous⟩

@[export pantograph_expr_proj_to_app]
-def exprProjToApp (env: Environment) (e: Expr): Expr :=
+def exprProjToApp (env : Environment) (e : Expr) : Expr :=
  let anon : Expr := .mvar ⟨.anonymous⟩
  match analyzeProjection env e with
  | .field projector numParams =>
@ -66,9 +66,18 @@ def exprProjToApp (env: Environment) (e: Expr): Expr :=
 def _root_.Lean.Name.isAuxLemma (n : Lean.Name) : Bool := n matches .num (.str _ "_auxLemma") _

 /-- Unfold all lemmas created by `Lean.Meta.mkAuxLemma`. These end in `_auxLemma.nn` where `nn` is a number. -/
-@[export pantograph_unfold_aux_lemmas]
-def unfoldAuxLemmas (e : Expr) : CoreM Expr := do
-  Lean.Meta.deltaExpand e Lean.Name.isAuxLemma
+@[export pantograph_unfold_aux_lemmas_m]
+def unfoldAuxLemmas : Expr → CoreM Expr :=
+  (Meta.deltaExpand · Lean.Name.isAuxLemma)
+/-- Unfold all matcher applications -/
+@[export pantograph_unfold_matchers_m]
+def unfoldMatchers (expr : Expr) : CoreM Expr :=
+  Core.transform expr λ e => do
+    let .some mapp ← Meta.matchMatcherApp? e | return .continue e
+    let .some matcherInfo := (← getEnv).find? mapp.matcherName | panic! "Matcher must exist"
+    let f ← Meta.instantiateValueLevelParams matcherInfo mapp.matcherLevels.toList
+    let mdata := KVMap.empty.insert `matcher (DataValue.ofName mapp.matcherName)
+    return .visit $ .mdata mdata (f.betaRev e.getAppRevArgs (useZeta := true))

 /--
 Force the instantiation of delayed metavariables even if they cannot be fully
@ -85,91 +94,92 @@ This function ensures any metavariable in the result is either
 1. Delayed assigned with its pending mvar not assigned in any form
 2. Not assigned (delay or not)
 -/
-partial def instantiateDelayedMVars (eOrig: Expr) : MetaM Expr := do
-  --let padding := String.join $ List.replicate level "│ "
-  --IO.println s!"{padding}Starting {toString eOrig}"
-  let mut result ← Meta.transform (← instantiateMVars eOrig)
-    (pre := fun e => e.withApp fun f args => do
-      let .mvar mvarId := f | return .continue
-      --IO.println s!"{padding}├V {e}"
-      let mvarDecl ← mvarId.getDecl
+partial def instantiateDelayedMVars (expr : Expr) : MetaM Expr :=
+  withTraceNode `Pantograph.Delate (λ _ex => return m!":= {← Meta.ppExpr expr}") do
+  let mut result ← Meta.transform (← instantiateMVars expr)
+    λ e => e.withApp fun f args => do
+    let .mvar mvarId := f | return .continue
+    trace[Pantograph.Delate] "V {e}"
+    let mvarDecl ← mvarId.getDecl

-      -- This is critical to maintaining the interdependency of metavariables.
-      -- Without setting `.syntheticOpaque`, Lean's metavariable elimination
-      -- system will not make the necessary delayed assigned mvars in case of
-      -- nested mvars.
-      mvarId.setKind .syntheticOpaque
+    -- This is critical to maintaining the interdependency of metavariables.
+    -- Without setting `.syntheticOpaque`, Lean's metavariable elimination
+    -- system will not make the necessary delayed assigned mvars in case of
+    -- nested mvars.
+    mvarId.setKind .syntheticOpaque

-      mvarId.withContext do
-        let lctx ← MonadLCtx.getLCtx
-        if mvarDecl.lctx.any (λ decl => !lctx.contains decl.fvarId) then
-          let violations := mvarDecl.lctx.decls.foldl (λ acc decl? => match decl? with
-            | .some decl => if lctx.contains decl.fvarId then acc else acc ++ [decl.fvarId.name]
-            | .none => acc) []
-          panic! s!"In the context of {mvarId.name}, there are local context variable violations: {violations}"
+    mvarId.withContext do
+      let lctx ← MonadLCtx.getLCtx
+      if mvarDecl.lctx.any (λ decl => !lctx.contains decl.fvarId) then
+        let violations := mvarDecl.lctx.decls.foldl (λ acc decl? => match decl? with
+          | .some decl => if lctx.contains decl.fvarId then acc else acc ++ [decl.fvarId.name]
+          | .none => acc) []
+        panic! s!"In the context of {mvarId.name}, there are local context variable violations: {violations}"

-        if let .some assign ← getExprMVarAssignment? mvarId then
-          --IO.println s!"{padding}├A ?{mvarId.name}"
-          assert! !(← mvarId.isDelayedAssigned)
-          return .visit (mkAppN assign args)
-        else if let some { fvars, mvarIdPending } ← getDelayedMVarAssignment? mvarId then
-          --let substTableStr := String.intercalate ", " $ Array.zipWith fvars args (λ fvar assign => s!"{fvar.fvarId!.name} := {assign}") |>.toList
-          --IO.println s!"{padding}├MD ?{mvarId.name} := ?{mvarIdPending.name} [{substTableStr}]"
+      if let .some assign ← getExprMVarAssignment? mvarId then
+        trace[Pantograph.Delate] "A ?{mvarId.name}"
+        assert! !(← mvarId.isDelayedAssigned)
+        return .visit (mkAppN assign args)
+      else if let some { fvars, mvarIdPending } ← getDelayedMVarAssignment? mvarId then
+        if ← isTracingEnabledFor `Pantograph.Delate then
+          let substTableStr := String.intercalate ", " $ Array.zipWith fvars args (λ fvar assign => s!"{fvar.fvarId!.name} := {assign}") |>.toList
+          trace[Pantograph.Delate]"MD ?{mvarId.name} := ?{mvarIdPending.name} [{substTableStr}]"

-          if args.size < fvars.size then
-            throwError "Not enough arguments to instantiate a delay assigned mvar. This is due to bad implementations of a tactic: {args.size} < {fvars.size}. Expr: {toString e}; Origin: {toString eOrig}"
-          --if !args.isEmpty then
-            --IO.println s!"{padding}├── Arguments Begin"
-          let args ← args.mapM self
-          --if !args.isEmpty then
-            --IO.println s!"{padding}├── Arguments End"
-          if !(← mvarIdPending.isAssignedOrDelayedAssigned) then
-            --IO.println s!"{padding}├T1"
-            let result := mkAppN f args
-            return .done result
-
-          let pending ← mvarIdPending.withContext do
-            let inner ← instantiateDelayedMVars (.mvar mvarIdPending) --(level := level + 1)
-            --IO.println s!"{padding}├Pre: {inner}"
-            pure <| (← inner.abstractM fvars).instantiateRev args
-
-          -- Tail arguments
-          let result := mkAppRange pending fvars.size args.size args
-          --IO.println s!"{padding}├MD {result}"
+        if args.size < fvars.size then
+          throwError "Not enough arguments to instantiate a delay assigned mvar. This is due to bad implementations of a tactic: {args.size} < {fvars.size}. Expr: {toString e}; Origin: {toString expr}"
+        if !args.isEmpty then
+          trace[Pantograph.Delate] "─ Arguments Begin"
+        let args ← args.mapM self
+        if !args.isEmpty then
+          trace[Pantograph.Delate] "─ Arguments End"
+        if !(← mvarIdPending.isAssignedOrDelayedAssigned) then
+          trace[Pantograph.Delate] "T1"
+          let result := mkAppN f args
          return .done result
-        else
-          assert! !(← mvarId.isAssigned)
-          assert! !(← mvarId.isDelayedAssigned)
-          --if !args.isEmpty then
-          --  IO.println s!"{padding}├── Arguments Begin"
-          let args ← args.mapM self
-          --if !args.isEmpty then
-          --  IO.println s!"{padding}├── Arguments End"

-          --IO.println s!"{padding}├M ?{mvarId.name}"
-          return .done (mkAppN f args))
-  --IO.println s!"{padding}└Result {result}"
+        let pending ← mvarIdPending.withContext do
+          let inner ← instantiateDelayedMVars (.mvar mvarIdPending)
+          trace[Pantograph.Delate] "Pre: {inner}"
+          pure <| (← inner.abstractM fvars).instantiateRev args
+
+        -- Tail arguments
+        let result := mkAppRange pending fvars.size args.size args
+        trace[Pantograph.Delate] "MD {result}"
+        return .done result
+      else
+        assert! !(← mvarId.isAssigned)
+        assert! !(← mvarId.isDelayedAssigned)
+        if !args.isEmpty then
+          trace[Pantograph.Delate] "─ Arguments Begin"
+        let args ← args.mapM self
+        if !args.isEmpty then
+          trace[Pantograph.Delate] "─ Arguments End"
+
+        trace[Pantograph.Delate] "M ?{mvarId.name}"
+        return .done (mkAppN f args)
+  trace[Pantoraph.Delate] "Result {result}"
  return result
  where
-  self e := instantiateDelayedMVars e --(level := level + 1)
+  self e := instantiateDelayedMVars e

 /--
 Convert an expression to an equiavlent form with
 1. No nested delayed assigned mvars
-2. No aux lemmas
+2. No aux lemmas or matchers
 3. No assigned mvars
 -/
@[export pantograph_instantiate_all_m]
-def instantiateAll (e: Expr): MetaM Expr := do
+def instantiateAll (e : Expr) : MetaM Expr := do
  let e ← instantiateDelayedMVars e
  let e ← unfoldAuxLemmas e
+  let e ← unfoldMatchers e
  return e

 structure DelayedMVarInvocation where
-  mvarIdPending: MVarId
-  args: Array (FVarId × (Option Expr))
+  mvarIdPending : MVarId
+  args : Array (FVarId × (Option Expr))
  -- Extra arguments applied to the result of this substitution
-  tail: Array Expr
+  tail : Array Expr

 -- The pending mvar of any delayed assigned mvar must not be assigned in any way.
@[export pantograph_to_delayed_mvar_invocation_m]
@ -594,4 +604,7 @@ protected def GoalState.diag (goalState: GoalState) (parent?: Option GoalState :
      | other => s!"[{other}]"
    parentHasMVar (mvarId: MVarId): Bool := parent?.map (λ state => state.mctx.decls.contains mvarId) |>.getD true

+initialize
+  registerTraceClass `Pantograph.Delate
+
 end Pantograph
--- a/Pantograph/Frontend/MetaTranslate.lean
+++ b/Pantograph/Frontend/MetaTranslate.lean
@ -62,7 +62,7 @@ private partial def translateExpr (srcExpr: Expr) : MetaTranslateM Expr := do
  let sourceMCtx ← getSourceMCtx
  -- We want to create as few mvars as possible
  let (srcExpr, _) := instantiateMVarsCore (mctx := sourceMCtx) srcExpr
-  --IO.println s!"Transform src: {srcExpr}"
+  trace[Pantograph.Frontend.MetaTranslate] "Transform src: {srcExpr}"
  let result ← Core.transform srcExpr λ e => do
    let state ← get
    match e with
@ -100,10 +100,10 @@ partial def translateLocalDecl (srcLocalDecl: LocalDecl) : MetaTranslateM LocalD
  addTranslatedFVar srcLocalDecl.fvarId fvarId
  match srcLocalDecl with
  | .cdecl index _ userName type bi kind => do
-    --IO.println s!"[CD] {userName} {toString type}"
+    trace[Pantograph.Frontend.MetaTranslate] "[CD] {userName} {toString type}"
    return .cdecl index fvarId userName (← translateExpr type) bi kind
  | .ldecl index _ userName type value nonDep kind => do
-    --IO.println s!"[LD] {toString type} := {toString value}"
+    trace[Pantograph.Frontend.MetaTranslate] "[LD] {toString type} := {toString value}"
    return .ldecl index fvarId userName (← translateExpr type) (← translateExpr value) nonDep kind

 partial def translateLCtx : MetaTranslateM LocalContext := do
@ -162,4 +162,7 @@ end MetaTranslate

 export MetaTranslate (MetaTranslateM)

+initialize
+  registerTraceClass `Pantograph.Frontend.MetaTranslate
+
 end Pantograph.Frontend
--- a/Pantograph/Protocol.lean
+++ b/Pantograph/Protocol.lean
@ -346,10 +346,9 @@ structure FrontendProcess where
  -- One of these two must be supplied: Either supply the file name or the content.
  fileName?: Option String := .none
  file?: Option String := .none
-  -- If set to true, read the header (otherwise discards the header)
+  -- Whether to read the header
  readHeader : Bool := false
-  -- If set to true, Pantograph's environment will be altered to whatever is
-  -- after the compilation units.
+  -- Alter the REPL environment after the compilation units.
  inheritEnv : Bool := false
  -- collect tactic invocations
  invocations: Bool := false
--- a/Test/Common.lean
+++ b/Test/Common.lean
@ -108,7 +108,7 @@ def strToTermSyntax (s: String): CoreM Syntax := do
    (input := s)
    (fileName := ← getFileName) | panic! s!"Failed to parse {s}"
  return stx
-def parseSentence (s: String): Elab.TermElabM Expr := do
+def parseSentence (s : String) (expectedType? : Option Expr := .none) : Elab.TermElabM Expr := do
  let stx ← match Parser.runParserCategory
    (env := ← MonadEnv.getEnv)
    (catName := `term)
@ -116,7 +116,7 @@ def parseSentence (s: String): Elab.TermElabM Expr := do
    (fileName := ← getFileName) with
    | .ok syn => pure syn
    | .error error => throwError "Failed to parse: {error}"
-  Elab.Term.elabTerm (stx := stx) .none
+  Elab.Term.elabTerm (stx := stx) expectedType?

 def runTacticOnMVar (tacticM: Elab.Tactic.TacticM Unit) (goal: MVarId): Elab.TermElabM (List MVarId) := do
    let (_, newGoals) ← tacticM { elaborator := .anonymous } |>.run { goals := [goal] }
--- a/Test/Delate.lean
+++ b/Test/Delate.lean
@ -3,10 +3,9 @@ import Pantograph.Delate
 import Test.Common
 import Lean

-open Lean
-namespace Pantograph.Test.Delate
+open Lean Pantograph

-open Pantograph
+namespace Pantograph.Test.Delate

 deriving instance Repr, DecidableEq for Protocol.BoundExpression

@ -113,6 +112,13 @@ def test_projection_exists (env: Environment) : IO LSpec.TestSeq:= runTest do
  checkEq "numParams" numParams 2
  checkEq "numFields" numFields 2

+def test_matcher : TestT Elab.TermElabM Unit := do
+  let t ← parseSentence "Nat → Nat"
+  let e ← parseSentence "fun (n : Nat) => match n with | 0 => 0 | k => k" (.some t)
+  let .some _ ← Meta.matchMatcherApp? e.bindingBody! | fail "Must be a matcher app"
+  let e' ← instantiateAll e
+  checkTrue "ok" <| ← Meta.isTypeCorrect e'
+
 def suite (env: Environment): List (String × IO LSpec.TestSeq) :=
  [
    ("serializeName", do pure test_serializeName),
@ -123,6 +129,7 @@ def suite (env: Environment): List (String × IO LSpec.TestSeq) :=
    ("Instance", test_instance env),
    ("Projection Prod", test_projection_prod env),
    ("Projection Exists", test_projection_exists env),
+    ("Matcher", runTestTermElabM env test_matcher),
  ]

 end Pantograph.Test.Delate
--- a/doc/repl.md
+++ b/doc/repl.md
@ -46,14 +46,15 @@ See `Pantograph/Protocol.lean` for a description of the parameters and return va
  Save/Load a goal state to/from a file. The environment is not carried with the
  state. The user is responsible to ensure the sender/receiver instances share
  the same environment.
-* `frontend.process { ["fileName": <fileName>,] ["file": <str>], invocations:
+* `frontend.process { ["fileName": <fileName>,] ["file": <str>], readHeader: <bool>, inheritEnv: <bool>, invocations:
  <bool>, sorrys: <bool>, typeErrorsAsGoals: <bool>, newConstants: <bool> }`:
  Executes the Lean frontend on a file, collecting the tactic invocations
  (`"invocations": true`), the sorrys and type errors into goal states
  (`"sorrys": true`), and new constants (`"newConstants": true`). In the case of
  `sorrys`, this command additionally outputs the position of each captured
-  `sorry`. Warning: Behaviour is unstable in case of multiple `sorry`s. Use the
-  draft tactic if possible.
+  `sorry`. Conditionally inherit the environment from executing the file.
+  Warning: Behaviour is unstable in case of multiple `sorry`s. Use the draft
+  tactic if possible.

 ## Errors