Improved error reporting with positions

[cc1516.git] / src / parse.icl

diff --git a/src/parse.icl b/src/parse.icl
index bc93239..f5cb0c8 100644 (file)
--- a/src/parse.icl
+++ b/src/parse.icl
@@ -12,6 +12,7 @@ import Control.Applicative
 import Data.Func
 from Data.List import intercalate, replicate, instance Functor []
 from Text import class Text(concat), instance Text String
+import GenPrint
 
 import yard
 import lex
@@ -172,8 +173,9 @@ trans2 t f = satTok t >>= \(_, r).pure (f r)
 trans1 :: TokenValue a -> Parser Token a
 trans1 t r = trans2 t $ const r
 
+derive gPrint TokenValue
 satTok :: TokenValue -> Parser Token Token
-satTok t = satisfy ((===) t)
+satTok t = top >>= \tok=:(pos, tv) -> if (t === tok) (return tok) (fail <?> (printToString t, pos))
 
 parseSepList :: TokenValue (Parser Token a) -> Parser Token [a]
 parseSepList sep p =