FW: Another H'98 Report query

Simon Peyton-Jones simonpj@microsoft.com
Wed, 13 Feb 2002 09:00:01 -0800


There was a short thread relating to Malcolm's proposal, below.
The tenor of the discussion was that indeed his proposal makes
sense.   It excludes no programs, and makes the language more
consistent. =20

I propose to adopt it.


-----Original Message-----
From: Malcolm Wallace [mailto:Malcolm.Wallace@cs.york.ac.uk]=20
Sent: 31 January 2002 11:08
To: Haskell list
Subject: Another H'98 Report query

The revised H'98 Report, in the section on Modules, 5.2 (Export Lists),
under the description of the forms T (c_i,...) and C (f_i,...) for
explicitly named constructors, fieldnames, and methods of the respective
type or class, says:

    The subordinate names c_i (f_i) must not contain duplicates.

Yet later in the text it is stated that

    Exports lists are cumulative: the set of entities exported by an
    export list is the union of the entities exported by the individual
    items of the list.

I see no reason to disallow duplicates at the subordinate level if they
are permitted otherwise.


    module M (T,T(C))) where		-- legal
    module M (T(),T(C))) where		-- legal
    module M (T(C),T(C))) where		-- legal
    module M (T(C,C)) where		-- illegal

I propose we should drop the text that disallows duplicates, to make the
last example legal.


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