Currently if you want to convert an array of strings to lower (or upper) you have to write a little thing to process through every element of the array and put it in a new array. This isn't an extremely complex thing to write, but it could be reasonably streamlined by making toLower or toUpper do it automatically.

Proposed syntax:

_lowerArray = toLower ["AN","aRrAy","OF","StRiNgS"];

resulting in:

["an","array","of","strings"]

For bonus points it could accept any array and convert any strings in it while leaving the rest untouched, but I accept that may be out of scope.