Remove function clause from Internal (#2389)

- closes #2363

src/Juvix/Compiler/Builtins/Effect.hs

@@ -95,8 +95,9 @@ registerFun fi = do
       a =% b = (a ==% b) freeVars
       clauses :: [(Expression, Expression)]
       clauses =
-        [ (clauseLhsAsExpression c, c ^. clauseBody)
-          | c <- toList (fi ^. funInfoDef . funDefClauses)
+        [ (clauseLhsAsExpression op (toList pats), body)
+          | Just cls <- [unfoldLambdaClauses (fi ^. funInfoDef . funDefBody)],
+            (pats, body) <- toList cls
         ]
   case zipExactMay (fi ^. funInfoClauses) clauses of
     Nothing -> error "builtin has the wrong number of clauses"

src/Juvix/Compiler/Concrete/Language.hs

@@ -358,6 +358,7 @@ deriving stock instance (Ord (FixitySyntaxDef 'Scoped))
 data FixityDef = FixityDef
   { _fixityDefSymbol :: S.Symbol,
     _fixityDefFixity :: Fixity,
+    -- | Used internally for printing parentheses.
     _fixityDefPrec :: Int
   }
   deriving stock (Show, Eq, Ord)

src/Juvix/Compiler/Core/Translation/FromInternal.hs

@@ -312,7 +312,7 @@ preFunctionDef f = do
       Nothing ->
         map
           getPatternName
-          (head (f ^. Internal.funDefClauses) ^. Internal.clausePatterns)
+          (fst (Internal.unfoldLambda (f ^. Internal.funDefBody)))
 
     normalizeBuiltinName :: Maybe BuiltinFunction -> Text -> Text
     normalizeBuiltinName blt name = case blt of
@@ -378,7 +378,10 @@ mkFunBody ::
   Internal.FunctionDef ->
   Sem r Node
 mkFunBody ty f =
-  mkBody ty (f ^. Internal.funDefName . nameLoc) (fmap (\c -> (c ^. Internal.clausePatterns, c ^. Internal.clauseBody)) (f ^. Internal.funDefClauses))
+  mkBody
+    ty
+    (f ^. Internal.funDefName . nameLoc)
+    (pure (Internal.unfoldLambda (f ^. Internal.funDefBody)))
 
 mkBody ::
   forall r.

src/Juvix/Compiler/Internal/Extra.hs

@@ -81,7 +81,7 @@ genFieldProjection ::
   Int ->
   Sem r FunctionDef
 genFieldProjection _funDefName info fieldIx = do
-  clause <- genClause
+  body' <- genBody
   let (inductiveParams, constrArgs) = constructorArgTypes info
       implicity = constructorImplicity info
       saturatedTy = unnamedParameter' implicity (constructorReturnType info)
@@ -94,18 +94,22 @@ genFieldProjection _funDefName info fieldIx = do
         _funDefInstance = False,
         _funDefBuiltin = Nothing,
         _funDefPragmas = mempty,
-        _funDefClauses = pure clause,
+        _funDefBody = body',
         _funDefType = foldFunType (inductiveArgs ++ [saturatedTy]) retTy,
         ..
       }
   where
-    genClause :: Sem r FunctionClause
-    genClause = do
+    genBody :: Sem r Expression
+    genBody = do
       (pat, vars) <- genConstructorPattern (getLoc _funDefName) info
       let body = toExpression (vars !! fieldIx)
-      return
-        FunctionClause
-          { _clauseName = _funDefName,
-            _clausePatterns = [pat],
-            _clauseBody = body
+          cl =
+            LambdaClause
+              { _lambdaPatterns = pure pat,
+                _lambdaBody = body
+              }
+      return . ExpressionLambda $
+        Lambda
+          { _lambdaType = Nothing,
+            _lambdaClauses = pure cl
           }

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

@@ -158,24 +158,17 @@ subsHoles s = over leafExpressions helper
       ExpressionInstanceHole h -> fromMaybe e (s ^. at h)
       _ -> e
 
-instance HasExpressions FunctionClause where
-  leafExpressions f c = do
-    _clauseBody <- leafExpressions f (c ^. clauseBody)
-    _clausePatterns <- traverse (leafExpressions f) (c ^. clausePatterns)
-    pure FunctionClause {_clauseName = c ^. clauseName, ..}
-
 instance HasExpressions Example where
   leafExpressions f = traverseOf exampleExpression (leafExpressions f)
 
 instance HasExpressions FunctionDef where
-  -- leafExpressions f (FunctionDef name ty clauses bi) = do
   leafExpressions f FunctionDef {..} = do
-    clauses' <- traverse (leafExpressions f) _funDefClauses
+    body' <- leafExpressions f _funDefBody
     ty' <- leafExpressions f _funDefType
     examples' <- traverse (leafExpressions f) _funDefExamples
     pure
       FunctionDef
-        { _funDefClauses = clauses',
+        { _funDefBody = body',
           _funDefType = ty',
           _funDefExamples = examples',
           _funDefTerminating,
@@ -316,6 +309,21 @@ viewConstructorType = first (map (^. paramType)) . unfoldFunType
 constructorArgs :: Expression -> [Expression]
 constructorArgs = fst . viewConstructorType
 
+unfoldLambdaClauses :: Expression -> Maybe (NonEmpty (NonEmpty PatternArg, Expression))
+unfoldLambdaClauses t = do
+  ExpressionLambda Lambda {..} <- return t
+  let mkClause :: LambdaClause -> (NonEmpty PatternArg, Expression)
+      mkClause LambdaClause {..} = first (appendList _lambdaPatterns) (unfoldLambda _lambdaBody)
+  return (mkClause <$> _lambdaClauses)
+
+-- Unfolds *single* clause lambdas
+unfoldLambda :: Expression -> ([PatternArg], Expression)
+unfoldLambda t = case t of
+  ExpressionLambda Lambda {..}
+    | LambdaClause {..} :| [] <- _lambdaClauses ->
+        first (toList _lambdaPatterns <>) (unfoldLambda _lambdaBody)
+  _ -> ([], t)
+
 -- | a -> (b -> c)  ==> ([a, b], c)
 unfoldFunType :: Expression -> ([FunctionParameter], Expression)
 unfoldFunType t = case t of
@@ -513,9 +521,9 @@ leftEq a b free =
     . evalState (mempty @(HashMap Name Name))
     $ matchExpressions (toExpression a) (toExpression b)
 
-clauseLhsAsExpression :: FunctionClause -> Expression
-clauseLhsAsExpression cl =
-  foldApplication (toExpression (cl ^. clauseName)) (map toApplicationArg (cl ^. clausePatterns))
+clauseLhsAsExpression :: Name -> [PatternArg] -> Expression
+clauseLhsAsExpression clName pats =
+  foldApplication (toExpression clName) (map toApplicationArg pats)
 
 infix 4 ==%
 

src/Juvix/Compiler/Internal/Extra/DependencyBuilder.hs

@@ -195,7 +195,7 @@ goFunctionDefHelper f = do
   when (f ^. funDefInstance) $
     goInstance f
   goExpression (Just (f ^. funDefName)) (f ^. funDefType)
-  mapM_ (goFunctionClause (f ^. funDefName)) (f ^. funDefClauses)
+  goExpression (Just (f ^. funDefName)) (f ^. funDefBody)
 
 -- constructors of an inductive type depend on the inductive type, not the other
 -- way round; an inductive type depends on the types of its constructors
@@ -204,11 +204,6 @@ goConstructorDef indName c = do
   addEdge (c ^. inductiveConstructorName) indName
   goExpression (Just indName) (c ^. inductiveConstructorType)
 
-goFunctionClause :: (Members '[State DependencyGraph, State StartNodes, Reader ExportsTable] r) => Name -> FunctionClause -> Sem r ()
-goFunctionClause p c = do
-  mapM_ (goPattern (Just p)) (c ^. clausePatterns)
-  goExpression (Just p) (c ^. clauseBody)
-
 goPattern :: forall r. (Member (State DependencyGraph) r) => Maybe Name -> PatternArg -> Sem r ()
 goPattern n p = case p ^. patternArgPattern of
   PatternVariable {} -> return ()

src/Juvix/Compiler/Internal/Language.hs

@@ -86,7 +86,7 @@ data FunctionDef = FunctionDef
   { _funDefName :: FunctionName,
     _funDefType :: Expression,
     _funDefExamples :: [Example],
-    _funDefClauses :: NonEmpty FunctionClause,
+    _funDefBody :: Expression,
     _funDefTerminating :: Bool,
     _funDefInstance :: Bool,
     _funDefBuiltin :: Maybe BuiltinFunction,
@@ -96,15 +96,6 @@ data FunctionDef = FunctionDef
 
 instance Hashable FunctionDef
 
-data FunctionClause = FunctionClause
-  { _clauseName :: FunctionName,
-    _clausePatterns :: [PatternArg],
-    _clauseBody :: Expression
-  }
-  deriving stock (Eq, Generic, Data)
-
-instance Hashable FunctionClause
-
 data Iden
   = IdenFunction Name
   | IdenConstructor Name
@@ -214,7 +205,7 @@ data Lambda = Lambda
   deriving stock (Eq, Generic, Data)
 
 data LambdaClause = LambdaClause
-  { _lambdaPatterns :: NonEmpty PatternArg, -- only explicit patterns are allowed
+  { _lambdaPatterns :: NonEmpty PatternArg,
     _lambdaBody :: Expression
   }
   deriving stock (Eq, Generic, Data)
@@ -327,7 +318,6 @@ makeLenses ''Example
 makeLenses ''PatternArg
 makeLenses ''Import
 makeLenses ''FunctionDef
-makeLenses ''FunctionClause
 makeLenses ''InductiveDef
 makeLenses ''AxiomDef
 makeLenses ''ModuleBody'
@@ -438,11 +428,8 @@ instance HasLoc LambdaClause where
 instance HasLoc Lambda where
   getLoc l = getLocSpan (l ^. lambdaClauses)
 
-instance HasLoc FunctionClause where
-  getLoc f = getLoc (f ^. clauseName) <> getLoc (f ^. clauseBody)
-
 instance HasLoc FunctionDef where
-  getLoc f = getLoc (f ^. funDefName) <> getLocSpan (f ^. funDefClauses)
+  getLoc f = getLoc (f ^. funDefName) <> getLoc (f ^. funDefBody)
 
 instance HasLoc MutualBlockLet where
   getLoc (MutualBlockLet defs) = getLocSpan defs

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

@@ -238,26 +238,18 @@ instance PrettyCode FunctionDef where
     builtin' <- fmap (kwBuiltin <+>) <$> mapM ppCode (f ^. funDefBuiltin)
     funDefName' <- ppCode (f ^. funDefName)
     funDefType' <- ppCode (f ^. funDefType)
-    clauses' <- mapM ppCode (f ^. funDefClauses)
+    body' <- ppCode (f ^. funDefBody)
     return $
       builtin'
         <?+> funDefName'
           <+> kwColon
           <+> funDefType'
-            <> hardline
-            <> vsep (toList clauses')
+            <> oneLineOrNext (kwAssign <+> body')
 
 instance PrettyCode PreLetStatement where
   ppCode = \case
     PreLetFunctionDef f -> ppCode f
 
-instance PrettyCode FunctionClause where
-  ppCode c = do
-    funName <- ppCode (c ^. clauseName)
-    clausePatterns' <- hsepMaybe <$> mapM ppCodeAtom (c ^. clausePatterns)
-    clauseBody' <- ppCode (c ^. clauseBody)
-    return $ nest 2 (funName <+?> clausePatterns' <+> kwAssign <+> clauseBody')
-
 instance PrettyCode Import where
   ppCode i = do
     name' <- ppCode (i ^. importModule . moduleIxModule . moduleName)

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

@@ -435,28 +435,34 @@ goTopFunctionDef FunctionDef {..} = do
   _funDefType <- goDefType
   _funDefExamples <- goExamples _signDoc
   _funDefPragmas <- goPragmas _signPragmas
-  _funDefClauses <- goBody
+  _funDefBody <- goBody
   let fun = Internal.FunctionDef {..}
   whenJust _signBuiltin (registerBuiltinFunction fun . (^. withLocParam))
   return fun
   where
-    goBody :: Sem r (NonEmpty Internal.FunctionClause)
+    goBody :: Sem r Internal.Expression
     goBody = do
       commonPatterns <- concatMapM (fmap toList . argToPattern) _signArgs
-      let _clauseName = goSymbol _signName
-          goClause :: FunctionClause 'Scoped -> Sem r Internal.FunctionClause
+      let goClause :: FunctionClause 'Scoped -> Sem r Internal.LambdaClause
           goClause FunctionClause {..} = do
-            let _clauseName = goSymbol _signName
-            _clauseBody <- goExpression _clausenBody
-            extraPatterns <- toList <$> (mapM goPatternArg _clausenPatterns)
-            let _clausePatterns = commonPatterns <> extraPatterns
-            return Internal.FunctionClause {..}
+            _lambdaBody <- goExpression _clausenBody
+            extraPatterns <- mapM goPatternArg _clausenPatterns
+            let _lambdaPatterns = prependList commonPatterns extraPatterns
+            return Internal.LambdaClause {..}
       case _signBody of
         SigBodyExpression body -> do
-          _clauseBody <- goExpression body
-          let _clausePatterns = commonPatterns
-          return (pure Internal.FunctionClause {..})
-        SigBodyClauses cls -> mapM goClause cls
+          body' <- goExpression body
+          return $ case nonEmpty commonPatterns of
+            Nothing -> body'
+            Just _lambdaPatterns -> do
+              let _lambdaBody = body'
+                  _lambdaType :: Maybe Internal.Expression = Nothing
+                  _lambdaClauses = pure Internal.LambdaClause {..}
+              Internal.ExpressionLambda Internal.Lambda {..}
+        SigBodyClauses cls -> do
+          _lambdaClauses <- mapM goClause cls
+          let _lambdaType :: Maybe Internal.Expression = Nothing
+          return (Internal.ExpressionLambda Internal.Lambda {..})
 
     goDefType :: Sem r Internal.Expression
     goDefType = do