Wed Mar 3 11:23:41 CET 2010
The Actor model is not composable
I recently ran into this in practice (in Java): a system with a lot of
message passing suddenly needed a sequential behaviour. This then
lead me to remove all synchronous message passing and use semaphores
It talks about something I've tried to hint at earlier:
* FP allows for ``exponential'' expressivity: since everything can
compose with everything else, the total number of expressable
behaviours grows very fast.
* Stateful programming allow for ``linear'' expressivity: you can
add stuff, but in general it can't be combined as-is with other
This is of course a black&white picture, but it seems to be true in
spirit: it's harder to reach exponential expressivity in stateful
languages exactly because of the inertia present in state -- hidden
assumptions as mentioned in .