remove unnecessary brackets

[fp.git] / src / Lambda.hs

diff --git a/src/Lambda.hs b/src/Lambda.hs
index f9fbe2b..54c4065 100644 (file)
--- a/src/Lambda.hs
+++ b/src/Lambda.hs
@@ -28,7 +28,7 @@ parseVar = do
 parseLambda :: Parser Term
 parseLambda = do
   char '\\'
-  vars <- many1 (parseVar <* char ' ')
+  vars <- sepBy1 parseVar (char ' ')
   char '.'
   t <- parseTerm
   return $! createLambda vars t
@@ -40,15 +40,26 @@ createLambda _ _ = error "createLambda failed"
 
 parseApp :: Parser Term
 parseApp = do
+  aps <- sepBy1 (parseBraces <|> parseLambda <|> parseVar) (char ' ')
+  return $! createApp aps
+
+createApp :: [Term] -> Term
+createApp [t] = t
+createApp (t:ts:tss) = createApp (App t ts : tss)
+createApp [] = error "empty createApp"
+
+parseBraces :: Parser Term
+parseBraces = do
   char '('
   t <- parseTerm
-  char ' '
-  r <- parseTerm
   char ')'
-  return $! App t r
+  return t 
 
 parseTerm :: Parser Term
-parseTerm = parseVar <|> parseLambda <|> parseApp
+parseTerm = parseApp <|>
+            parseBraces <|>
+            parseLambda <|>
+            parseVar
 
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