This is a somewhat older thread, but I ask you to enlighten me. Norman Ramsey wrote:
A fact that I know but don't understand the implication of is that Haskell dispatches on the static type of a value, whereas OO languages dispatch on the dynamic type of a value. But I suspect I'll leave that out :-)
Dean Herington:
Perhaps I misunderstand, but I would suggest that "fact" is, if not incorrect, at least oversimplified. I would say Haskell dispatches on the dynamic type of a value, in the sense that a single polymorphic function varies its behavior based on the specific type(s) of its argument(s). What may distinguish Haskell from typical OO languages (I'm not an expert on them) is that in Haskell such polymorphic functions could (always or at least nearly so) be specialized statically for their uses at different types.
Fergus Henderson wrote:
I agree. The above characterization is highly misleading. It would be more accurate and informative to say that both Haskell and OO languages dispatch on the dynamic type of a value.
================================ Now my brain ceased to understand... Are you sure that OO dispatch schemas are based on the *argument* type? I would say that - unless I am dead wrong, the OO languages such as Smalltalk do not dispatch on dynamic types of a value. The receiver is known, so its vir. f. table (belonging to the receiver's class) is known as well, the dispatching is based on the *message identifiers* independently of subsidiary arguments. Only after that - perhaps - some "reversions", message propagation depending on the arg(s) value(s), etc. may take place, but all this is irrelevant... Forgive me if I write stupidities. Jerzy Karczmarczuk