(I'm not sure why my postings seem somewhat anonymous, I'll mess with the headers in this post to see if that fixes it. I post to other mailman lists and haven't noticed this problem.) I'm working through Paul Hudak's SOE, and have a question about problem 9.4, which is to define a function applyEach. I've come up with several versions, but not one which usefully uses currying (the exercise doesn't explicitly say to use currying, but that's the only thing in this section). My real question is whether I should be trying to apply currying here. Solutions are welcome, but I can think of several good reasons not to post solutions to this forum. The behavior of applyEach should be obvious from my attempts below. Output: applyEach [(+1), (+3), (+2)] 1 => [2,4,3] :: [Integer] Recursive version:
applyEach :: [a->b] -> a -> [b] applyEach [] _ = [] applyEach (h:t) x = (h x) : (applyEach t x)
Now with higher order functions:
applyEach' :: [a->b] -> a -> [b] applyEach' funs x = map applyx funs where applyx (fun) = fun x
With Lambda:
applyEach'' :: [a->b] -> a -> [b] applyEach'' funs x = map (\fun-> fun x) funs
With Currying: ? peace, isaac P.S. I'm enjoying this book a great deal :-)