Learning Haskell: How to remove an item from a List in Haskell

Question

Trying to learn Haskell. I am trying to write a simple function to remove a number from a list without using built-in function (delete...I think). For the sake of simplicity, le

Answer 1

The : operator doesn't do what you think it does:

(:) :: a -> [a] -> [a]

It takes an item of type a and adds it to the beginning of a list of type a. You're using it to join two lists of type a. For that, you need to use ++:

(++) :: [a] -> [a] -> [a]

Also, if you make a recursive function, it needs an ending condition. So try this:

removeItem _ [] = []
removeItem x (y:ys) = areTheySame x y ++ removeItem x ys

That way, when you get to the end of the list, the function will stop recursing.