Agreed. I know a lot of Ruby and a bit of C, and it's great that I can write quite high level abstractions that run a few orders of magnitude faster than the eq

Agreed. I know a lot of Ruby and a bit of C, and it's great that I can write quite high level abstractions that run a few orders of magnitude faster than the equivalent Ruby. This is not to say that Haskell is always more performant. From the little I've done it seems as though you need an awareness of when thunks would take up more memory than the results of your expression and how to write code accordingly.