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 _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe