Please write a function in Haskell which does the following, without using any prelude functions or importing any libraries. Make relevant helper functions where needed.

Write a function, variations, which creates all permutations of a non-empty input string and removes duplicates if present. The order of permutations doesn't matter. Example: input3 = "abc" expectedOutput 3=["abc","acb","bac","bca","cab","cba"] Note: No imports are allowed