I don't think it's highly problematic.  I agree that it would be nice to have the type and value levels have a similar structure, but if there are compelling reasons to do otherwise that fine too.

You could still allow symbol type variables if they have an explicit binding occurence, which you can always(?) do with type variables.

  -- Lennart

On Dec 5, 2007 11:34 PM, Wolfgang Jeltsch <g9ks157k@acme.softbase.org> wrote:
Am Mittwoch, 5. Dezember 2007 17:05 schrieb Simon Peyton-Jones:
> […]

> Anyway, while on this subject, I am considering making the following
> change:
>
>         make all operator symbols into type constructors
>         (currently they are type variables)

This would be highly problematic!

Concerning syntax, everything that holds for values should also hold for
types.  For values, identifiers starting with a capital letter and operators
starting with a colon denote "constants", everything else denotes variables.
Exactly the same should hold for types since otherwise we would get a very
confusing result.  So we should keep things as they are concerning type
constructors and type variables.  And we should think about type functions
being denoted by lower case identifiers and operators not starting with a
colon because they are similar to non-constructor functions on the value
level.

We should strive for a systematic language and therefore not make ad-hoc
decisions which for the moment seem to serve a purpose in some specific
cases.

> […]

Best wishes,
Wolfgang
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