Had the same experience while learning scheme. Lazy eval, continuation, continuation-passing-style, coroutine, OOP (yes!), lambda stuff, dynamic/lexical scope,

Had the same experience while learning scheme. Lazy eval, continuation, continuation-passing-style, coroutine, OOP (yes!), lambda stuff, dynamic/lexical scope, closure, thunks, tail recursion (not all of that is specific to scheme of course, but you get the idea)... I'm still not OK with monads though :-)