-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Creighton Hogg wrote:
Now maybe I'm being dense here, but would you really *want* a way in Haskell to do something like memo :: (a->b) -> a->b since it changes the semantics of the function? It seems like a better abstraction would be to have memo :: (a->b)-> M a b where M is an instance of Arrow so that you can keep a proper notion of composition between memoized functions. Is there something wrong with my thinking?
"memoize f gives you back a function that maintains a cache of previously computed values, so that subsequent calls with the same input will be faster." Speed isn't part of Haskell function semantics (luckily, or we wouldn't be able to have an optimizer in the first place). memoize does not change the semantics of the function (I think) Your "better abstraction" is, anyway, better in terms of being implementable in existing Haskell - you might need an (Eq a) context or something. However it interferes with code structure for a non-semantical change (strong effects on memory use and speed which you might _want_ to manage more explicitly, but that's not theoretically affecting purity) Isaac -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFGXZPDHgcxvIWYTTURAi9fAJ44oIE85tZd+OtUOKswZnleBdt7eACeJuET 65AkQ2zI15CH6pnMHFmQddE= =n5OS -----END PGP SIGNATURE-----