Re: [Haskell-cafe] Questions about the Functor class and it's use in "Data types à la carte"

Ah, good old seq. How I loathe it. Seriously, though, good catch. I always forget about seq when I'm doing stuff like this.

When using seq and _|_ in the context of categories, keep in mind that Haskell "composition" (.) is not really composition in the category-theoretic sense, because it adds extra laziness. Use this instead: (.!) f g x = f `seq` g `seq` f (g x) -Yitz