-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 7/30/10 11:48 , Ivan Lazar Miljenovic wrote: > Ertugrul Soeylemez <[email protected]> writes: >> it's a bit hidden in Haskell, but a monad instance consists of three >> functions: >> >> fmap :: (a -> b) -> (m a -> m b) > > You don't even need fmap defined for it to be a monad, since fmap f m = > liftM f m = m >>= (return . f)
fmap/join and return/bind are isomorphic; given either set, you can produce the other. The usual category-theory definition of monads uses the former; Haskell uses the latter, because it allows operations to easily be chained together. - -- brandon s. allbery [linux,solaris,freebsd,perl] [email protected] system administrator [openafs,heimdal,too many hats] [email protected] electrical and computer engineering, carnegie mellon university KF8NH -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.10 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkxS9foACgkQIn7hlCsL25Uc2ACgoLG8uti3d0oWrv1H56fRJ3W4 xZIAn1KotatZklktHpKEwdib6AKXrNOr =Io9w -----END PGP SIGNATURE----- _______________________________________________ Haskell-Cafe mailing list [email protected] http://www.haskell.org/mailman/listinfo/haskell-cafe
