Distance to nearest vowel
Write a function that takes a string as argument. Each character in the string will be a letter. The function should return a sequence containing the distances from each corresponding letter in the string to the nearest vowel in the string.
For example:
(nearest-vowels "aeiou") ;=> [0 0 0 0 0] ;; if the letter is a vowel, the distance is 0
(nearest-vowels "babbb") ;=> [1 0 1 2 3]
(nearest-vowels "babbba") ;=> [1 0 1 2 1 0]