[louthy]

"Computation is not just about functions, if computation was just about functions then quicksort and bubblesort would be the same because they're computing the same function. A computing device is something that goes through a sequence of states. What an assignment statement is doing is it is telling you "here is a new state". Functions alone don't solve the problems of programming because programs (on the whole) are non-deterministic; on the other hand, imperative programs are using assignment statements to compute functions, and that's silly."

That exact phrase was said to Erik Meijer by Leslie Lamport when Erik interviewed Leslie. [1]

It seems clear (if you take Leslie's word as gospel) that there is room for 'Mostly Functional'. That is, accept that your program goes through a series of states, but use pure functions to calculate those states.

However, as an imperative programmer who's found Haskell over the past few years (thanks, in a large part to Erik Meijer), I happen to think that Haskell has it just about right.

[1] http://channel9.msdn.com/Shows/Going+Deep/E2E-Erik-Meijer-an...