On Wednesday 06 April 2005 16:15, Eijiro Sumii wrote:
> So here it goes: why don't we have polymorphic +, -, etc. while we
> have polymorphic =, <, etc.?  Many novices and (at least) some experts
> feel that +., -., etc. are not quite nice.  Why not define +, -,
> etc. for as many types as possible such as integers, floating-point
> numbers, and tuples?  I think they can be implemented almost in the
> same efficient way as =.  They can also raise an exception if applied
> to unsupported values such as functions, just as = does.

I'm just curious, but what would you have expected the result of:

# (1, 2, 3) * (2, 3, 4);;

to be? i.e. an inner product, element-wise multiplication or an outer product?

> P.S. I believe I'm not proposing anything as serious as Haskell type
> classes.

Oh, this isn't serious? ;-)

> If so, I can perhaps restate my question as: why is the line drawn between =
> and + now?

I would say that polymorphic comparisons are useful in many more circumstances 
than polymorphic arithmetics would be, so their inclusion is justified.

-- 
Dr Jon D Harrop, Flying Frog Consultancy Ltd.
Objective CAML for Scientists
http://www.ffconsultancy.com/products/ocaml_for_scientists