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The [] metaoperator

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From:
Autrijus Tang
Date:
May 14, 2005 07:54
Subject:
The [] metaoperator
Message ID:
20050514145338.GA79539@aut.dyndns.org
On Sat, May 14, 2005 at 10:56:29PM +1000, Damian Conway wrote:
>     8. To verify the monotonicity of a sequence:
> 
>            $is_monotonic = [<] @numbers;

Hey.  Does this mean that the [] metaoperator folds with the
associativity of the operator inside it?

That is, if the operator inside is right-associative, it functions as
foldr; if the operator is left-associative, it functions as a foldl; and
if the operator is chain-associative like <, it assumes the special,
short-circuiting chained-folding semantic?

    [>]  1, 2, 3;    # 1 > 2 > 3	# 3 is not evaluated
    [**] 1, 2, 3;    # 1 ** (2 ** 3)
    [+]  1, 2, 3;    # (1 + 2) + 3

If so, should I send patches to S03, or is it already in the works?

Finally, what does this mean?

    say [x];

Is it a repeating metaoperator on an empty list, or a single-element
array reference that contains the return value of calling &x()?

Thanks,
/Autrijus/


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