parsing lambdas

[cc1516.git] / parse.icl

diff --git a/parse.icl b/parse.icl
index e13b870..a79ad2f 100644 (file)
--- a/parse.icl
+++ b/parse.icl
@@ -27,14 +27,26 @@ parser ts = case runParser parseProgram ts of
        x = fst x
 
 parseProgram :: Parser Token AST
-parseProgram = AST <$> some parseFunDecl
+parseProgram = many parseLetDecl >>= \fds1->
+                some parseFunDecl >>= \fds2->
+                pure $ AST (fds1++fds2)
+
+parseLetDecl :: Parser Token FunDecl
+parseLetDecl = peekPos >>= \p->
+                satTok LetToken >>|
+                parseFunType >>= \mt->
+                parseIdent >>= \f->
+                satTok AssignmentToken >>|
+                parseExpr >>= \e->
+                satTok SColonToken >>|
+                pure (FunDecl p f [] (Just mt) [] [ReturnStmt $ Just e])
 
 parseFunDecl :: Parser Token FunDecl
 parseFunDecl = liftM6 FunDecl
     (peekPos)
     (parseIdent)
        (parseBBraces $ parseSepList CommaToken parseIdent)
-       (optional parseFunType)
+       (optional (satTok DoubleColonToken *> parseFunType))
        (satTok CBraceOpenToken *> many parseVarDecl)
        (many parseStmt <* satTok CBraceCloseToken)
 
@@ -73,7 +85,9 @@ parseStmt = parseIfStmt <|> parseWhileStmt <|>
                parseOneLine = pure <$> parseStmt
 
 parseFunType :: Parser Token Type
-parseFunType = satTok DoubleColonToken *> parseFT
+parseFunType = parseFT >>= \t -> case t of
+        t1 ->> t2   = pure t
+        simpleT     = pure $ FuncType simpleT
        where
         parseFT :: Parser Token Type
                parseFT = (liftM2 (->>) (parseSF <* satTok ArrowToken) (parseFT)) <|>
@@ -99,7 +113,9 @@ parseType =
        (IdType <$> parseIdent)
 
 parseExpr :: Parser Token Expr
-parseExpr = //Operators in order of binding strength
+parseExpr = parseValueExpr <|> parseLambda
+parseValueExpr :: Parser Token Expr
+parseValueExpr = //Operators in order of binding strength
        parseOpR (trans1 ColonToken BiCons) $
        parseOpR (trans1 PipesToken BiOr) $
        parseOpR (trans1 AmpersandsToken BiAnd) $
@@ -140,6 +156,11 @@ parseExpr = //Operators in order of binding strength
                                pure $ FunExpr pos ident args fs) <|>
                        (VarExpr pos <$> parseVarDef)
 
+parseLambda :: Parser Token Expr
+parseLambda = LambdaExpr <$> peekPos 
+                        <*> (satTok BackslashToken *> some parseIdent)
+                        <*> (satTok ArrowToken *> parseExpr)
+
 makeStrExpr :: Pos [Char] -> Expr
 makeStrExpr p [] = EmptyListExpr p
 makeStrExpr p [x:xs] = Op2Expr p (CharExpr zero x) BiCons (makeStrExpr p xs)
@@ -194,15 +215,16 @@ peekPos = fst <$> peek
 derive gPrint TokenValue
 derive gEq TokenValue
 satTok :: TokenValue -> Parser Token Token
-satTok t = top >>= \tok=:({line,col},token) -> if (eq t token)
+satTok t = top >>= \tok=:({line,col},token) -> if (tokEq t token)
        (pure tok) (fail <?> PositionalError line col
-               ("ParseError: Unexpected token: " +++ printToString token))
-       where
-               eq (IdentToken _) (IdentToken _) = True
-               eq (NumberToken _) (NumberToken _) = True
-               eq (CharToken _) (CharToken _) = True
-               eq (StringToken _) (StringToken _) = True
-               eq x y = gEq {|*|} x y
+               ("ParseError: Unexpected token: " +++ printToString token 
+            +++ "\nExpected: " +++ printToString t))
+
+tokEq (IdentToken _) (IdentToken _) = True
+tokEq (NumberToken _) (NumberToken _) = True
+tokEq (CharToken _) (CharToken _) = True
+tokEq (StringToken _) (StringToken _) = True
+tokEq x y = gEq {|*|} x y
 
 parseSepList :: TokenValue (Parser Token a) -> Parser Token [a]
 parseSepList sep p =