Haskell.

This obscure language represents a peculiar corner of the programming language world called functional languages. One of the peculiar things about such languages is that they don’t have variables. Although Haskell isn’t widely known among programmers, those who know of functional languages suspect that they, too, are rather slow

It needs to be said very firmly that LISP is not a functional language at all. My suspicion is that the success of Lisp set back the development of a properly functional style of programming by at least ten years. -- David Turner