* fixed 'satisfy'

Author: Nick Obedin

src/Text/Parsing/Parser/String.purs

@@ -34,9 +34,13 @@ char = ParserT $ \s' ->
     _ -> { consumed: true, input: drop 1 s', result: Right (charAt 0 s') }
 
 satisfy :: forall m. (Monad m) => (String -> Boolean) -> ParserT String m String
-satisfy f = do
-  p <- char
-  if f p then return p else fail "Character did not satisfy predicate"
+satisfy f = ParserT $ \s' -> case s' of
+    "" -> return { consumed: false, input: s', result: Left (strMsg "Unexpected EOF") }
+    _  ->
+        let c = charAt 0 s'
+        in return $ if f c
+            then { consumed: true, input: drop 1 s', result: Right c }
+            else { consumed: false, input: s', result: Left (strMsg "Character did not satisfy predicate") }
 
 whiteSpace :: forall m. (Monad m) => ParserT String m String
 whiteSpace = do