Probably because many university students are taught Clean (the 'other' purely functional lazy programming language) [1] which is developed in the Netherlands.

[1] http://en.wikipedia.org/wiki/Clean_(programming_language)

I would not bet on that. Utrecht (http://www.cs.uu.nl/wiki/UHC) is in the Netherlands, too. I also expect/guess that it has more CS students than Nijmegen

So every dutch university teaches a language they themselves wrote the compiler for. The university of twente used to teach FP in a miranda dialect called amanda, which ofcourse was developed at utwente :p

The University of Groningen uses Haskell and Hugs for their functional programming course ;). So, there seem to be exceptions to that rule.

I thought Clean was mostly taught only at Radboud, since it originated there.

Yeah, Utrecht University has some of the world's leading Haskell researchers, I think it is taught in Groningen as well. In Nijmegen they teach Clean, which is very similar to Haskell.

Did not know that about Utrecht Uni.