Citation needed. The argument for Haskell is usually about correctness; industry perception and my experience is that writing a Haskell version of a program will usually take longer than an "acceptably buggy" Python or Ruby equivalent.

Well, there's the 1994 US Navy experiment that shows Haskell is a serious contender for rapid prototyping: http://cpsc.yale.edu/sites/default/files/files/tr1049.pdf

Of course, there was no Ruby back then. The comparison was against C++, Ada, Awk (!?), something called "relational Lisp" and a variety of in-house languages. Haskell comes just after Lisp in development time, with a mind-boggling 8 hours! (No C++ times were reported... heh heh). The Haskell solution also got top marks in general, not just in development time. As a downside, some of the reviewers didn't understand it because they weren't well-versed in functional programming, and felt some of the Haskell code was "tricky".

All of that's about runtime performance, not programming time.