parsing lambdas

[cc1516.git] / parse.icl

diff --git a/parse.icl b/parse.icl
index 766f1ce..a79ad2f 100644 (file)
--- a/parse.icl
+++ b/parse.icl
@@ -1,5 +1,6 @@
 implementation module parse
 
+import GenPrint
 import StdString
 import StdTuple
 import StdList
@@ -14,7 +15,6 @@ import Data.Func
 import StdMisc
 from Data.List import intercalate, replicate, instance Functor []
 from Text import class Text(concat), instance Text String
-import GenPrint
 
 import yard
 import lex
@@ -27,21 +27,34 @@ 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)
 
 parseStmt :: Parser Token Stmt
 parseStmt = parseIfStmt <|> parseWhileStmt <|>
        parseSColon parseAssStmt <|> parseSColon parseReturnStmt <|>
-       (parseSColon parseFunCall >>= \(ident, args)->pure $ FunStmt ident args)
+       (parseSColon parseFunCall 
+               >>= \(ident, args, fs)->pure $ FunStmt ident args fs)
        where
                parseSColon :: (Parser Token a) -> Parser Token a
                parseSColon p = p <* satTok SColonToken
@@ -72,12 +85,15 @@ 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 (->>) 
-                               ((parseBBraces parseFT <|> parseType) <* satTok ArrowToken)
-                               parseFT) <|> parseType
+               parseFT = (liftM2 (->>) (parseSF <* satTok ArrowToken) (parseFT)) <|>
+                       parseSF
+               parseSF :: Parser Token Type
+               parseSF = parseBBraces parseFT <|> parseType
 
 parseVarDecl :: Parser Token VarDecl
 parseVarDecl = liftM4 VarDecl
@@ -97,7 +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) $
@@ -125,9 +143,8 @@ parseExpr = //Operators in order of binding strength
 
                parseBasicExpr :: Parser Token Expr
                parseBasicExpr = peekPos >>= \pos ->
+                       (trans2 (StringToken []) (\(StringToken cs)->makeStrExpr pos cs)) <|>
                        (TupleExpr pos <$> (parseTuple parseExpr)) <|>
-                       (parseFunCall >>= \(ident, args)->parseFieldSelectors >>= \fs->
-                               pure $ FunExpr pos ident args fs) <|>
                        parseBBraces parseExpr <|>
                        trans1 EmptyListToken (EmptyListExpr pos) <|>
                        trans1 TrueToken (BoolExpr pos True) <|>
@@ -135,21 +152,36 @@ parseExpr = //Operators in order of binding strength
                        trans2 (NumberToken zero) (\(NumberToken i)->IntExpr pos i) <|>
                        trans2 (CharToken zero) (\(CharToken c)->CharExpr pos c) <|>
                        (Op1Expr pos <$> parseOp1 <*> parseExpr) <|>
+                       (parseFunCall >>= \(ident, args, fs)->
+                               pure $ FunExpr pos ident args fs) <|>
                        (VarExpr pos <$> parseVarDef)
 
-parseFunCall :: Parser Token (String, [Expr])
-parseFunCall = tuple <$> parseIdent <*> (
-       (parseBBraces $ parseSepList CommaToken parseExpr) <|> pure [])
+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)
+
+parseFunCall :: Parser Token (String, [Expr], [FieldSelector])
+parseFunCall = liftM3 (\x y z->(x, y, z))
+       parseIdent 
+       (parseBBraces $ parseSepList CommaToken parseExpr)
+       parseFieldSelectors
 
 parseVarDef :: Parser Token VarDef
 parseVarDef = liftM2 VarDef parseIdent parseFieldSelectors
 
 parseFieldSelectors :: Parser Token [FieldSelector]
-parseFieldSelectors = many (satTok DotToken *> (
-       (parseIdent >>= \i.if (i == "hd") (pure FieldHd) empty) <|>
-       (parseIdent >>= \i.if (i == "tl") (pure FieldTl) empty) <|>
-       (parseIdent >>= \i.if (i == "fst") (pure FieldFst) empty) <|>
-       (parseIdent >>= \i.if (i == "snd") (pure FieldSnd) empty)))
+parseFieldSelectors = many (satTok DotToken *> 
+       parseIdent >>= \i->case i of
+               "hd" = pure FieldHd
+               "tl" = pure FieldTl 
+               "fst" = pure FieldFst
+               "snd" = pure FieldSnd 
+               _ = empty)
 
 parseOp1 :: Parser Token Op1
 parseOp1 = trans1 DashToken UnMinus <|> trans1 ExclamationToken UnNegation
@@ -183,14 +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 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 =
@@ -198,7 +232,7 @@ parseSepList sep p =
        (liftM pure p) <|> pure empty
 
 parseIdent :: Parser Token String
-parseIdent = trans2 (IdentToken "") (\(IdentToken e).toString e)
+parseIdent = trans2 (IdentToken "") (\(IdentToken e)->toString e)
 
 //liftM only goes to liftM5
 liftM6 f m1 m2 m3 m4 m5 m6 = f <$> m1 <*> m2 <*> m3 <*> m4 <*> m5 <*> m6