X-Git-Url: https://git.martlubbers.net/?a=blobdiff_plain;f=src%2Fyard.icl;h=81e58837495df4a2fa86e9f7c817835b8cda89fa;hb=7c16c9353b324301ee8c028e39c33aa2a46895f8;hp=b5e3c61f885002285eab6d8c6fc38aa6bd189385;hpb=43d45105726b3ad3e5cc5165f8c9b066ec8d2790;p=cc1516.git

diff --git a/src/yard.icl b/src/yard.icl
index b5e3c61..81e5883 100644
--- a/src/yard.icl
+++ b/src/yard.icl
@@ -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)