On Thu, 2010-05-13 at 10:06 -0300, Edgar Z. Alvarenga wrote:
Hi,
I created a small Genetic Algorithm program, replicating this work ("Statistical mechanics of program systems" - JP Neirotti, N. Caticha, Journal of Physics A Math and Gen) made in Lisp. When a restricted the problem just for one type, the Haskell program worked perfectly with much less lines and a lot faster than the Lisp program. The problem was when I tried to generalize to polymorphic types.
I'm using this datatype to represent a program:
data Tree a = Bin (String, (a -> a -> a)) (Tree a) (Tree a) | Un (String, (a -> a)) (Tree a) | V
And can convert a Tree to a function with:
treeToFunc :: Tree a -> a -> a treeToFunc (Bin f l r) = (snd f) <$> treeToFunc l <*> treeToFunc r treeToFunc (Un f u) = (snd f).(treeToFunc u) treeToFunc V = id
I already create another datatype to represent a polymorphic program (using GADT or existentials), but doesn't see a way to convert this kind of tree to a function.
Anyone has any idea?
Thanks, Edgar
Hmm. What GDAT/existential do you use (for lazy people who do not want to read paper)? How is it programmed in Lisp? data Tree a where Bin :: String -> (c -> (a, b)) -> (a -> b -> c) -> Tree a -> Tree b -> Tree c Un :: String -> (a -> a) -> Tree a V :: Tree a treeToFunc :: Tree a -> a -> a treeToFunc (Bin _ f g l r) v = let ~(x, y) = f v in g (treeToFunc l x) (treeToFunc r y) treeToFunc (Un _ f) v = f v treeToFunc V v = v Or data Tree a where Bin :: String -> Tree a -> Tree b -> Tree (a, b) Un :: String -> (a -> a) -> Tree a V :: Tree a treeToFunc :: Tree a -> a -> a treeToFunc (Bin _ l r) (a, b) = (treeToFunc l a, treeToFunc r b) treeToFunc (Un _ f) v = f v treeToFunc V v = v Both compiles but I'm not sure if they are what you want. Regards