[kryptiskt]

It takes an idea[0] and runs with it as far as it goes. The best part is that when they got to obstacles like handling of IO, they didn't take the easy route and compromise the vision in favor of a pragmatic solution. Instead they went into unexplored territory and came back with monads, which proved an extremely fertile ground for more than IO.

Obviously, Haskell being an academic language helps here, since novel ideas lead to papers and boring old ideas don't.

[0]: That is statically typed lazy functional programming.