Re: newbie: running a state transformer in context of a state rea der

Tue, 20 Feb 2001 17:52:33 -0800, Konst Sushenko pisze:

lookahead p = do { s <- fetch ; lift (evalState p s) }

is typed as

lookahead:: State MyState Maybe a -> State MyState Maybe (a,MyState)

but i need

lookahead:: State MyState Maybe a -> State MyState Maybe a

myEvalState = liftM fst yourEvalState Andy Gill's monadic modules provide evalState as a wrapper for runState, which throws away the state component returned. -- __("< Marcin Kowalczyk * qrczak@knm.org.pl http://qrczak.ids.net.pl/ \__/ ^^ SYGNATURA ZASTÊPCZA QRCZAK