deliverable:

Well, I'm thinking in terms of OOD/OOA/OOP -- Design, Architecture, Programming. That's about the only way to model a bog system. Say I have a stock market model -- I'll have a database of tickers, a simulator to backtest things, a trading strategy, etc.

Do Haskell modules provide enough encapsulation to design a system in terms of them? What are the design/architecture units in Haskell if not OO-based?

Haskell's pretty big on encapsulation (we like our strong statically checked guarantees after all) Some of the encapsulation mechanisms used in large (>5k loc up to 100k + Haskell programs I've hacked on): modules qualified modules type classes to specify generic interfaces existential types to hide implementations completely (and statically) existentials using typeclasses to package the interface monads for state/effect encapsulation abstract data types data types with smart constructors first class modules via existentials purity laziness So the same kind of encapsulation as OO stuff provides (existentials are essentially OO objects), and a few more besides. Monads in particular are perfect for encapsulating interesting effects, and having that encapsulation statically enforced. Probably some of the OO refugees can think of other mechanisms. Cheers, Don