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{-
Example for a LR(0) grammar that causes the parser to loop!
frown --debug Loop1.g
Try
x "$" :: Maybe ()
Using
frown --debug --trace Loop1.g
shows why. Try
x "$"
-}
module Loop
where
import Monad
instance MonadPlus IO where
mzero = fail "mzero"
m `mplus` n = putStrLn "** choice" >> m >> putStrLn "** backtrack" >> n
frown ts = putStrLn "*** syntax error" >> return undefined
type Terminal = Char
type Result = IO
{-
frown _ = fail "syntax error"
-}
%{
Terminal = 'a' | 'b' | 'c' | *'$';
Nonterminal = x | y;
x : y, x, 'c';
y : ;
}%
|
