There has been [a question on Stack Overflow] asking for a way to group a
list by an equivalence relation. Several answers were proposed over time, and I
too [have offered a variant]. [I also wrote a benchmark.]
I propose that the function be added to the standard libraries.
I strongly support adding this to base, I personally have had to use something like this quite often. One suggestion I have though is to use [NonEmpty a] as the return type, as NonEmpty is already in base and it is a more accurate type.