Ozgur Akgun wrote:
Hi cafe,
Is such a thing possible,
add :: Int -> Int -> Int add x y = x + y
-- a list of partially applied functions adds = [add 3, add 5, add 7, add 3, add 5, add 8]
-- an example usage of the list k = map (\ f -> f 10 ) adds
add3s = filter (?) adds -- add3s = [add 3, add 3] addEvens = filter (?) adds --addEvens = [add 8]
I want to have functions in place of the ? signs. I guess one would need a way of extracting the applied value from a partially applied function (or totally, doesn't matter)
Well, sure you can: add3s = filter (\f -> f 0 == 3) adds addEvens = filter (\f -> isEven $ f 0) adds This is only possible since there is that special property of the addition that (add a) 0 == a forall a, i.e. you can extract the first parameter back out of the partial applied function by passing 0 as a second parameter. It clearly depends on the function how much information about the parameters can be read from the result. -- Steffen