Re: records

[Jost Boekemeier <jostobfe@linux.zrz.TU-Berlin.DE>]

Maciej Stachowiak <mstachow@alum.mit.edu> writes:

> The way I have always seen it used in papers on type
> theory is that a polymorphic type is one that has one or more other types
> as a parameter.[...]
> sometype[T] = int, T -> (list T)

When we talk about the OO paradigm I think we should apply OO terminology.
Following Booch, Rumbaugh, Meyer, Stourstrup and others, the above example 
is a "template".  A template can be used to create new types. It consists
of a _generic_ type with one or more _concrete_ types as the parameter.

According to Rumbaugh, Booch, Wirth, Meyer and others an _operation_
is polymorph if there exists two or more _methods_ implementing the
operation. For example the operation "vehicle move" will be
implemented differendly for a car and a bike.  Although a car is a
vecicle and a bicicle is a vehicle and thus both use the same
operation, the methods are differend.


Jost