> I have built plenty of large software systems. And the source of cost in those systems is always -- by at least a factor of a 100 -- was coupling and imprecis

> I have built plenty of large software systems. And the source of cost in those systems is always -- by at least a factor of a 100 -- was coupling and imprecise semantics. One thing I find interesting about this is that a good type system, combined with something like OCaml's module system, is that you can force decoupling. In OCaml, you can create an abstract type, which cannot be used in any way that isn't specified through the interface. You don't have to wrap the runtime value in anything, it's purely a compile time abstraction.