Prelude> :load myFunctions.hs
[1 of 1] Compiling Main             ( myFunctions.hs, interpreted )
Ok, modules loaded: Main.
*Main> myIntersperse "." ["aaa","bbb","CCC","dDd"]

<interactive>:1:20:
    Couldn't match expected type `[Char]' with actual type `Char'
    Expected type: [[Char]]
      Actual type: [Char]
    In the expression: "aaa"
    In the second argument of `myIntersperse', namely
      `["aaa", "bbb", "CCC", "dDd"]'