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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: relax double parens in expression_function_declaration?
Date: Mon, 20 Feb 2017 21:16:18 +0000
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Date: 2017-02-20T21:16:18+00:00
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Stephen Leake <stephen_leake@stephe-leake.org> writes:

> However, I can't find a rule in the ARM that allows it.
> ARM 6.8 says:
>
>    expression_function_declaration ::=
>         [overriding_indicator]
>         function_specification is
>             (expression)
>             [aspect_specification];

Actually there is, I think, a typo: the first semicolon in
http://www.ada-auth.org/standards/rm12_w_tc1/html/RM-6-8.html#p2 should
be a pipe, '|'.

> This requires double parens:
>
>    function Key return Result is
>      ((A => 1,
>        B => 2));
>
> ARM 4.5.7(7) gives permission to remove the double parens for
> conditional_expression; is there a similar rule or AI for aggregates?

AARM 4.5.7(7.j),
http://www.ada-auth.org/standards/aarm12_w_tc1/html/AA-4-5-7.html#p7.j,
says

   The English-language rule applies in all places that could surround
   an expression with parentheses, including pragma arguments, type
   conversion and qualified expression operands, and array index
   expressions.

but it's far from clear what that means, & if it applies to aggregates,
why that couldn't have been made explicit in (7) in the first place!