On 30/05/2012, at 10:16 AM, Eric Rasmussen wrote:
One idea (contrived and silly though it is) is modeling a Courier that delivers message to Persons. There is a standard default reply for all Persons, some individuals have their own default reply, and there are conditional replies based on the sender. Each reply has the ability to alter a Person's mood. The goal of the exercise would be to read in a CSV file in the form of "To, From, Message", and then output the interactions based on rules.
Simulation is of course what Simula 67, the first well known object oriented language, was devised for. Simula 67 was also one of the first three languages I know of to include concurrency as a standard feature, the others being PL/I and Algol 68. And to an Erlang programmer, the obvious way to model a simulation is with one process per entity. It's also not accidental that Smalltalk has had concurrency since it first appeared, and the simulation example in the Blue Book (and the simulation library derived form it) makes essential use of concurrency. In ML I would use the Concurrent ML facilities (supported in SML/NJ and MLton). Using Haskell I would definitely consider simulation using concurrency. And objects per se might not be all that useful. In F# I would expect to use threads but not classes.