99 Clojure Problems – 20: Remove the Kth Element from a List

Return the list and the removed element in a tuple. Elements are numbered from 0.

Example:

(deftest p20-remove-at
  (is (= '((a c d) b) (remove-at 1 '(a b c d)))))

Solution:

A quick one: Reuse split from problem 17 to cut the input sequence into two parts. I called them head and tail, which is not quite accurate as head usually refers to the first element of a sequence only. You can then concatenate the head part and the tail part again into a single sequence. Calling rest on the tail before concatenating removes the right element. Calling first on the tail allows you to return the removed element as required (Source).

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