X-Git-Url: https://git.martlubbers.net/?a=blobdiff_plain;f=src%2Fyard.icl;h=81e58837495df4a2fa86e9f7c817835b8cda89fa;hb=f63b1c16836bebf6eef2baa5f20d4d6ebc73e4dd;hp=bded7fb94b2c110c8230f7acf8692c8b91a07de2;hpb=4c779c9791b03d96a76956e314cbc95f056448ce;p=cc1516.git

diff --git a/src/yard.icl b/src/yard.icl
index bded7fb..81e5883 100644
--- a/src/yard.icl
+++ b/src/yard.icl
@@ -24,7 +24,7 @@ runParser (Parser f) i = f i
 instance + Error where
     (+) ParseError r = r 
     (+) r ParseError = r
-    (+) _ r          = r
+    (+) r _          = r
  
 instance Functor (Parser a) where
     fmap f m = liftM f m
@@ -60,9 +60,17 @@ top = Parser \i -> case i of
     []      = (Left ParseError, [])
     [x:xs]  = (Right x, xs)
 
+peek :: Parser a a
+peek = Parser \i -> case i of
+    []      = (Left ParseError, [])
+    [x:xs]  = (Right x, [x:xs])
+
 satisfy :: (a -> Bool) -> Parser a a
 satisfy f = top >>= \r -> if (f r) (return r) fail
 
+check :: (a -> Bool) -> Parser a a
+check f = peek >>= \r -> if (f r) (return r) fail
+
 item :: a -> Parser a a | Eq a
 item a  = satisfy ((==)a)