Hello,
I hope these don't turn out to be RTFM questions, but I can't find them in my FM :-)
1) Is there a function to get the ith element from an array? 2) Is there a function to get the "index" of an entry in an array?
I've implemented these two functions below:
1) find 0 (x:xs) = x find n (x:xs) = find (n-1) xs
2)
index i (x:xs) =
if i == x
then 0
else 1 + index a xsThis was a fun exercise, but I can't shack off the feeling that I just re-invented the wheel.
I need these because I want to be able to swap any two elements from an array. This is my swap function:
-- swap i j array => swaps the ith and jth elements of 'array'.
--
swap i j arr = a_head ++ [item_j] ++ a_midd ++ [item_i] ++ a_tail
where a_head = [a | a <- arr, index a arr < i]
item_i = find i arr
a_midd = [a | a <- arr,(index a arr > i) && (index a arr < j)]
item_j = find j arr
a_tail = [a | a <- arr, index a arr > j]I'm sure this was a poor way to accomplish this, but it was a learning experience. If anyone would like to show me a more elegant solution, I would be happy to see it.
Cheers, Daniel. Haskell newbie. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
