Function that applies a function x times on an argument

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Write a doItX :: (a -> a -> a) -> a -> Int -> a function that applies the first parameter f x times on the second parameter.

doItX (*) 2 1 == 2

doItX (++) "a" 6 == "aaaaaa"

doItX (*) 2 3 == 8

I have the following code:

doItX f a x
  | x==1 = a
  | x>1 = doItX f (f a a) (x-1)

That works fine if x is 2 or less, but for the third example, it returns 16 instead of 8.



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