Fix typechecking of default arguments in signatures with trait arguments (#2998)

- Fixes #2994

src/Juvix/Compiler/Concrete/Data/NameSignature/Builder.hs

@@ -17,7 +17,12 @@ import Juvix.Compiler.Concrete.Translation.FromParsed.Analysis.Scoping.Error
 import Juvix.Prelude
 
 data NameSignatureBuilder s :: Effect where
-  AddSymbol :: IsImplicit -> Maybe (ArgDefault s) -> SymbolType s -> ExpressionType s -> NameSignatureBuilder s m ()
+  AddArgument ::
+    IsImplicit ->
+    Maybe (ArgDefault s) ->
+    Maybe (SymbolType s) ->
+    ExpressionType s ->
+    NameSignatureBuilder s m ()
   EndBuild :: Proxy s -> NameSignatureBuilder s m a
   -- | for debugging
   GetBuilder :: NameSignatureBuilder s m (BuilderState s)
@@ -34,6 +39,15 @@ data BuilderState (s :: Stage) = BuilderState
 makeLenses ''BuilderState
 makeSem ''NameSignatureBuilder
 
+addSymbol ::
+  (Members '[NameSignatureBuilder s] r) =>
+  IsImplicit ->
+  Maybe (ArgDefault s) ->
+  SymbolType s ->
+  ExpressionType s ->
+  Sem r ()
+addSymbol isImplicit mdefault sym ty = addArgument isImplicit mdefault (Just sym) ty
+
 class HasNameSignature (s :: Stage) d | d -> s where
   addArgs :: (Members '[NameSignatureBuilder s] r) => d -> Sem r ()
 
@@ -167,17 +181,23 @@ addInductiveParams = addInductiveParams' Explicit
 addConstructorParams :: (SingI s, Members '[NameSignatureBuilder s] r) => InductiveParameters s -> Sem r ()
 addConstructorParams = addInductiveParams' Implicit
 
-addSigArg :: (SingI s, Members '[NameSignatureBuilder s] r) => SigArg s -> Sem r ()
-addSigArg a = forM_ (a ^. sigArgNames) $ \case
-  ArgumentSymbol s ->
-    addSymbol
-      (a ^. sigArgImplicit)
-      (a ^. sigArgDefault)
-      s
-      (fromMaybe defaultType (a ^. sigArgType))
-    where
-      defaultType = run (runReader (getLoc a) Gen.smallUniverseExpression)
-  ArgumentWildcard {} -> return ()
+addSigArg :: forall s r. (SingI s, Members '[NameSignatureBuilder s] r) => SigArg s -> Sem r ()
+addSigArg a = case a ^. sigArgNames of
+  SigArgNamesInstance {} -> addArg (ArgumentWildcard (Wildcard (getLoc a)))
+  SigArgNames ns -> mapM_ addArg ns
+  where
+    defaultType = run (runReader (getLoc a) Gen.smallUniverseExpression)
+
+    addArg :: Argument s -> Sem r ()
+    addArg arg =
+      let sym :: Maybe (SymbolType s) = case arg of
+            ArgumentSymbol sy -> Just sy
+            ArgumentWildcard {} -> Nothing
+       in addArgument
+            (a ^. sigArgImplicit)
+            (a ^. sigArgDefault)
+            sym
+            (fromMaybe defaultType (a ^. sigArgType))
 
 type Re s r = State (BuilderState s) ': Error (BuilderState s) ': Error NameSignatureError ': r
 
@@ -187,20 +207,27 @@ re ::
   Sem (NameSignatureBuilder s ': r) a ->
   Sem (Re s r) a
 re = interpretTop3 $ \case
-  AddSymbol impl mdef k ty -> addSymbol' impl mdef k ty
+  AddArgument impl mdef k ty -> addArgument' impl mdef k ty
   EndBuild {} -> endBuild'
   GetBuilder -> get
 {-# INLINE re #-}
 
-addSymbol' :: forall s r. (SingI s) => IsImplicit -> Maybe (ArgDefault s) -> SymbolType s -> ExpressionType s -> Sem (Re s r) ()
-addSymbol' impl mdef sym ty = do
+addArgument' ::
+  forall s r.
+  (SingI s) =>
+  IsImplicit ->
+  Maybe (ArgDefault s) ->
+  Maybe (SymbolType s) ->
+  ExpressionType s ->
+  Sem (Re s r) ()
+addArgument' impl mdef msym ty = do
   curImpl <- gets @(BuilderState s) (^. stateCurrentImplicit)
   if
       | Just impl == curImpl -> addToCurrentBlock
       | otherwise -> startNewBlock
   where
-    errDuplicateName :: Symbol -> Sem (Re s r) ()
-    errDuplicateName _dupNameFirst =
+    errDuplicateName :: SymbolType s -> Symbol -> Sem (Re s r) ()
+    errDuplicateName sym _dupNameFirst =
       throw $
         ErrDuplicateName
           DuplicateName
@@ -208,22 +235,28 @@ addSymbol' impl mdef sym ty = do
               ..
             }
 
+    getNextIx :: (Members '[State (BuilderState s)] r') => Sem r' Int
+    getNextIx = do
+      idx <- gets @(BuilderState s) (^. stateNextIx)
+      modify' @(BuilderState s) (over stateNextIx succ)
+      return idx
+
     addToCurrentBlock :: Sem (Re s r) ()
     addToCurrentBlock = do
-      idx <- gets @(BuilderState s) (^. stateNextIx)
-      let itm =
-            NameItem
-              { _nameItemDefault = mdef,
-                _nameItemSymbol = sym,
-                _nameItemImplicit = impl,
-                _nameItemIndex = idx,
-                _nameItemType = ty
-              }
-          psym = symbolParsed sym
-      modify' @(BuilderState s) (over stateNextIx succ)
-      whenJustM (gets @(BuilderState s) (^. stateSymbols . at psym)) (errDuplicateName . symbolParsed)
-      modify' @(BuilderState s) (set (stateSymbols . at psym) (Just sym))
-      modify' @(BuilderState s) (set (stateCurrentBlock . at psym) (Just itm))
+      idx <- getNextIx
+      whenJust msym $ \(sym :: SymbolType s) -> do
+        let itm =
+              NameItem
+                { _nameItemDefault = mdef,
+                  _nameItemSymbol = sym,
+                  _nameItemImplicit = impl,
+                  _nameItemIndex = idx,
+                  _nameItemType = ty
+                }
+            psym = symbolParsed sym
+        whenJustM (gets @(BuilderState s) (^. stateSymbols . at psym)) (errDuplicateName sym . symbolParsed)
+        modify' @(BuilderState s) (set (stateSymbols . at psym) (Just sym))
+        modify' @(BuilderState s) (set (stateCurrentBlock . at psym) (Just itm))
 
     startNewBlock :: Sem (Re s r) ()
     startNewBlock = do
@@ -234,7 +267,7 @@ addSymbol' impl mdef sym ty = do
       modify' @(BuilderState s) (set stateNextIx 0)
       whenJust mcurImpl $ \curImpl ->
         modify' (over stateReverseClosedBlocks (NameBlock curBlock curImpl :))
-      addSymbol' impl mdef sym ty
+      addArgument' impl mdef msym ty
 
 endBuild' :: forall s r a. Sem (Re s r) a
 endBuild' = get @(BuilderState s) >>= throw

src/Juvix/Compiler/Concrete/Language/Base.hs

@@ -532,11 +532,37 @@ deriving stock instance Ord (ArgDefault 'Parsed)
 
 deriving stock instance Ord (ArgDefault 'Scoped)
 
+-- | This type makes explicit that only instance arguments are allowed to not
+-- have a name
+data SigArgNames (s :: Stage)
+  = SigArgNamesInstance
+  | SigArgNames (NonEmpty (Argument s))
+  deriving stock (Generic)
+
+instance Serialize (SigArgNames 'Scoped)
+
+instance NFData (SigArgNames 'Scoped)
+
+instance Serialize (SigArgNames 'Parsed)
+
+instance NFData (SigArgNames 'Parsed)
+
+deriving stock instance Show (SigArgNames 'Parsed)
+
+deriving stock instance Show (SigArgNames 'Scoped)
+
+deriving stock instance Eq (SigArgNames 'Parsed)
+
+deriving stock instance Eq (SigArgNames 'Scoped)
+
+deriving stock instance Ord (SigArgNames 'Parsed)
+
+deriving stock instance Ord (SigArgNames 'Scoped)
+
 data SigArg (s :: Stage) = SigArg
   { _sigArgDelims :: Irrelevant (KeywordRef, KeywordRef),
     _sigArgImplicit :: IsImplicit,
-    -- | Allowed to be empty only for Instance arguments
-    _sigArgNames :: [Argument s],
+    _sigArgNames :: SigArgNames s,
     _sigArgColon :: Maybe (Irrelevant KeywordRef),
     -- | The type is only optional for implicit arguments. Omitting the rhs is
     -- equivalent to writing `: Type`.

src/Juvix/Compiler/Concrete/Print/Base.hs

@@ -240,7 +240,7 @@ instance (PrettyPrint a, PrettyPrint b) => PrettyPrint (a, b) where
 instance (SingI s) => PrettyPrint (NameSignature s) where
   ppCode NameSignature {..}
     | null _nameSignatureArgs = noLoc (pretty @Text "<empty name signature>")
-    | otherwise = hsep . map ppCode $ _nameSignatureArgs
+    | otherwise = itemize . map ppCode $ _nameSignatureArgs
 
 instance (SingI s) => PrettyPrint (WildcardConstructor s) where
   ppCode WildcardConstructor {..} = do
@@ -1110,11 +1110,16 @@ instance (SingI s) => PrettyPrint (ArgDefault s) where
   ppCode ArgDefault {..} = do
     ppCode _argDefaultAssign <+> ppExpressionType _argDefaultValue
 
+instance (SingI s) => PrettyPrint (SigArgNames s) where
+  ppCode = \case
+    SigArgNamesInstance -> return ()
+    SigArgNames ns -> hsep (fmap ppCode ns)
+
 instance (SingI s) => PrettyPrint (SigArg s) where
   ppCode :: (Members '[ExactPrint, Reader Options] r) => SigArg s -> Sem r ()
   ppCode SigArg {..} = do
     let Irrelevant (l, r) = _sigArgDelims
-        names' = hsep (fmap ppCode _sigArgNames)
+        names' = ppCode _sigArgNames
         colon' = ppCode <$> _sigArgColon
         ty = ppExpressionType <$> _sigArgType
         arg = case _sigArgImplicit of

src/Juvix/Compiler/Concrete/Translation/FromParsed/Analysis/Scoping.hs

@@ -1098,11 +1098,16 @@ checkFunctionDef FunctionDef {..} = do
   registerNameSignature (sigName' ^. S.nameId) def
   registerFunctionDef @$> def
   where
+    checkSigArgNames :: SigArgNames 'Parsed -> Sem r (SigArgNames 'Scoped)
+    checkSigArgNames = \case
+      SigArgNamesInstance -> return SigArgNamesInstance
+      SigArgNames ns -> fmap SigArgNames . forM ns $ \case
+        ArgumentSymbol s -> ArgumentSymbol <$> bindVariableSymbol s
+        ArgumentWildcard w -> return (ArgumentWildcard w)
+
     checkArg :: SigArg 'Parsed -> Sem r (SigArg 'Scoped)
     checkArg arg@SigArg {..} = do
-      names' <- forM _sigArgNames $ \case
-        ArgumentSymbol s -> ArgumentSymbol <$> bindVariableSymbol s
-        ArgumentWildcard w -> return $ ArgumentWildcard w
+      names' <- checkSigArgNames _sigArgNames
       ty' <- mapM checkParseExpressionAtoms _sigArgType
       default' <- case _sigArgDefault of
         Nothing -> return Nothing

src/Juvix/Compiler/Concrete/Translation/FromSource.hs

@@ -1400,18 +1400,18 @@ functionDefinition allowOmitType allowInstance _signBuiltin = P.label "<function
               n <- parseArgumentName
               c <- Irrelevant <$> kw kwColon
               return (n, c)
-        (ns, c) <- case impl of
+        (ns :: SigArgNames 'Parsed, c) <- case impl of
           ImplicitInstance -> do
             ma <- optional parseArgumentNameColon
             return $ case ma of
-              Just (ns', c') -> ([ns'], Just c')
-              Nothing -> ([], Nothing)
+              Just (ns', c') -> (SigArgNames (pure ns'), Just c')
+              Nothing -> (SigArgNamesInstance, Nothing)
           Implicit -> do
-            ns <- some parseArgumentName
+            ns <- SigArgNames <$> some1 parseArgumentName
             c <- optional (Irrelevant <$> kw kwColon)
             return (ns, c)
           Explicit -> do
-            ns <- some parseArgumentName
+            ns <- SigArgNames <$> some1 parseArgumentName
             c <- Just . Irrelevant <$> kw kwColon
             return (ns, c)
         return (opn, ns, impl, c)

src/Juvix/Compiler/Internal/Pretty/Base.hs

@@ -37,6 +37,12 @@ instance PrettyCode Name where
     showNameId <- asks (^. optShowNameIds)
     return (prettyName showNameId n)
 
+instance PrettyCode ArgInfo where
+  ppCode ArgInfo {..} = do
+    name <- maybe (return kwWildcard) ppCode _argInfoName
+    defVal <- mapM (fmap (kwAssign <+>) . ppCode) _argInfoDefault
+    return (name <+?> defVal)
+
 instance PrettyCode Iden where
   ppCode :: (Member (Reader Options) r) => Iden -> Sem r (Doc Ann)
   ppCode i = case i of

src/Juvix/Compiler/Internal/Translation/FromConcrete.hs

@@ -20,6 +20,7 @@ import Juvix.Compiler.Concrete.Extra qualified as Concrete
 import Juvix.Compiler.Concrete.Gen qualified as Gen
 import Juvix.Compiler.Concrete.Language qualified as Concrete
 import Juvix.Compiler.Concrete.Pretty
+import Juvix.Compiler.Concrete.Print
 import Juvix.Compiler.Concrete.Translation.FromParsed.Analysis.Scoping qualified as Scoper
 import Juvix.Compiler.Concrete.Translation.FromParsed.Analysis.Scoping.Error
 import Juvix.Compiler.Internal.Builtins
@@ -393,11 +394,11 @@ goFunctionDef FunctionDef {..} = do
         goBlock :: NameBlock 'Scoped -> Sem r [Internal.ArgInfo]
         goBlock blk = do
           let tbl = indexedByInt (^. nameItemIndex) (blk ^. nameBlock)
-              mmaxIx = fst <$> IntMap.lookupMax tbl
-          case mmaxIx of
-            Nothing -> return []
+              mmaxIx :: Maybe Int = fst <$> IntMap.lookupMax tbl
+          execOutputList $ case mmaxIx of
+            Nothing -> output Internal.emptyArgInfo
             Just maxIx ->
-              execOutputList $ forM_ [0 .. maxIx] $ \idx ->
+              forM_ [0 .. maxIx] $ \idx ->
                 case tbl ^. at idx of
                   Nothing -> output Internal.emptyArgInfo
                   Just i -> do
@@ -462,7 +463,12 @@ goFunctionDef FunctionDef {..} = do
                         Concrete.ArgumentWildcard {} -> Nothing
                  in Internal.FunctionParameter {..}
 
-          return . fromMaybe (pure noName) $ nonEmpty (mk <$> _sigArgNames)
+              arguments :: Maybe (NonEmpty (Argument 'Scoped))
+              arguments = case _sigArgNames of
+                SigArgNamesInstance -> Nothing
+                SigArgNames ns -> Just ns
+
+          return (maybe (pure noName) (fmap mk) arguments)
 
     argToPattern :: SigArg 'Scoped -> Sem r (NonEmpty Internal.PatternArg)
     argToPattern arg@SigArg {..} = do
@@ -478,7 +484,12 @@ goFunctionDef FunctionDef {..} = do
               let _patternArgPattern = Internal.PatternVariable (goSymbol s)
                in return Internal.PatternArg {..}
             Concrete.ArgumentWildcard w -> goWildcard w
-      maybe (pure <$> noName) (mapM mk) (nonEmpty _sigArgNames)
+
+          arguments :: Maybe (NonEmpty (Argument 'Scoped))
+          arguments = case _sigArgNames of
+            SigArgNamesInstance -> Nothing
+            SigArgNames ns -> Just ns
+      maybe (pure <$> noName) (mapM mk) arguments
 
 goInductiveParameters ::
   forall r.

test/Typecheck/Positive.hs

@@ -326,7 +326,11 @@ tests =
     posTestAbsDir
       "Typecheck orphan file"
       (relToProject $(mkRelDir "tests/WithoutPackageFile"))
-      $(mkRelFile "Good.juvix")
+      $(mkRelFile "Good.juvix"),
+    posTest
+      "Default argument with trait in signature"
+      $(mkRelDir ".")
+      $(mkRelFile "issue2994.juvix")
   ]
     <> [ compilationTest t | t <- Compilation.tests
        ]

tests/positive/issue2994.juvix

@@ -0,0 +1,12 @@
+module issue2994;
+
+type T := t;
+
+type Maybe (a : Type) :=
+  | nothing
+  | just a;
+
+trait
+type SomeTrait A := mkSomeTrait {baz : A -> T};
+
+bar {{SomeTrait T}} (value : T) {maybeValue : Maybe T := nothing} : T := t;