Export lists in modules

[Johannes Waldmann]

Malcolm Wallace wrote:

> ... but that if there are thus two signatures for an entity, they
> must be identical.  This is to prevent the case where one modifies the
> definition of the function, making it more general, but forgets to
> modify the corresponding export.

Sounds like the perfect example to illustrate the point
that information shouldn't be doubled in the first place.

Can you say why you want the type in the export list?
Or really, why you want an export list at all?

Presumably because it constitutes the module's "interface",
but it is an ad-hoc thing (one interface per module).
We already have the concept of "type class"
which gives us re-usable interfaces. Isn't that much better?

I was discussing that in (the second paragraph of):
http://www.haskell.org//pipermail/haskell-prime/2006-January/000230.html

Respectfully submitted,
-- 
-- Johannes Waldmann -- Tel/Fax (0341) 3076 6479/80 --
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