I'm having trouble with the following exercise :
Utilizing list comprehension, define a function with the following signature:
reproduce :: [Int] -> [Int]
This function exchanges the every number in a list by x copies of itself.
eg:
input: reproduce[3,5,1]
output: [3,3,3,5,5,5,5,5,1]
I have done the following:
reproduce :: [Int] -> [Int]
reproduce xs = [ x | x <- [1,2..10 ] , x `elem` xs , replicate x x ]
My line of thought was making x belong to a small interval, x had to be an element of the original list so using elemx would only be added if it did belong to the original list, and replicating x , x times, to get the x copies of himself.
When i try to load this function i get the following error message:
Couldn't match expected type `Bool' with actual type `[Int]'
In the return type of a call of `replicate'
In the expression: replicate x x
In a stmt of a list comprehension: replicate x x
I have no idea how to fix this error, I'm assuming it has something to do with the elem part but I don't know what.
NOTE: This is a beginners exercise and thus should be solved in a simple manner.