“Aha!” moments

I just had one, reading SICP, looking at the coins code. I'd never really properly looked into it and thought it was kind of complex, but I just spent 15 minutes examining the code and I got it! Tackling an iterative version will be interesting.

ITT your last “aha!” moment

Note: if you don't remember when your last “aha!” moment was, perhaps you need to read SICP. (Or just consider that you really should.)

When I figured out how [i]QuickCheck[i] used type classes to basically recursively pattern match (at the type level) on function signatures to feed functions arbitrary (or should I say, Arbitrary) arguments. Its a technique I've since used to bind (in the sense of scripting languages) Haskell functions to work with my Lisp interpreter.