On Fri, Feb 22, 2013 at 7:27 PM, xiao Ling
h :: M Int -> M Int -> M Int h x y = bind ( \x-> g x y ) x
where g is
g :: Int -> W Int -> W Int g x y = y >>= (return . (+x))
for the monad:
data M a = M a deriving Show
Now I am a little confused, how can you put x in g if it takes an Int as first parameter but x is M Int?
Because it's a different "x". Lemme rewrite it slightly: h :: M Int -> M Int -> M Int h x y = bind ( \w -> g w y ) x All I did was replace the inner "x" with "w", to demonstrate that it has no relationship to the outer "x"; the \... -> syntax introduces new local bindings unrelated to any outside of it, in this case for "w" (or what he had "x", shadowing the original binding of "x" within the lambda). -- brandon s allbery kf8nh sine nomine associates allbery.b@gmail.com ballbery@sinenomine.net unix, openafs, kerberos, infrastructure, xmonad http://sinenomine.net