My CS professor tries to use less mainstream languages for exactly this purpose–to put everyone on an even playing field. The first two months of labs in the course are taught entirely in Haskell. The lectures are about DFAs and NFAs.

I've graded and TA'd the course for two years, and I think his approach works extremely well. It lets you filter out the people who really get it from the people who are just pattern matching from previous experience.