One of the parser combinator libraries for Clean had the (<:>)
combinator that captures the idiom (sorry!) in Doaitse's version.
Defined applicatively it would be:
(<:>) :: Applicative f => f a -> f [a] -> f [a]
(<:>) p1 p2 = (:) <$> p1 <*> p2
so pToken would be
pToken [] = pSucced []
pToken (x:xs) = pSym x <:> pToken xs
Admittedly this is not as succinct as
pToken = traverse pSym
... but I have used it from time to time.
Regards,
Stephen
2009/10/28 Ross Paterson
On Wed, Oct 28, 2009 at 06:07:49PM +0100, S. Doaitse Swierstra wrote:
pToken [] = pSucceed [] pToken (x:xs) = (:) <$> pSym x <*> pToken xs
pKeyword_Float = pToken "Float"
pToken = traverse pSym _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe