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Date: Tue, 19 Mar 2019 15:46:35 -0700
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Subject: Re: [PHP-DEV] RFC Draft: Comprehensions
From: smalyshev@gmail.com (Stanislav Malyshev)

Hi!

> In Python, the difference is that []-syntax gives you a list
> (pre-comupted), whereas without the [] you get a generator
> (generate-on-demand). This distinction is important because the
> generator might be iterating over something non-repeatable (e.g. another
> generator), or have some destructive or mutating effect. You also might
> not want to take the performance penalty of computing it every time you
> iterate over it.

Understandable, but I wonder how important it is for the short syntax
implied by list comprehensions? I mean, there could be all kinds of
complex cases, but those are easily doable by using already existing
functional syntax. If you need a generator over non-repeatable sequence,
you can get it now with a functional syntax. But in my experience, about
99% times I use this syntax (in Python) is a simple sequence filter and
I want to get a list out of it. I suspect PHP usage would be the same.
So I wonder if it's worth to bother inventing special syntax for
something that will be used in 1% of cases, and even in those cases
might be more readable as a generator function?

> Why not apply the same approach to PHP? There is iterator_to_array() to
> convert a generator to an array, so we may not need both syntaxes.
> However, I think using [] for something that is *not an array* is
> counter-intuitive.

No, I would definitely be for []-syntax producing an array. As I said,
that's in my experience what people usually want.

-- 
Stas Malyshev
smalyshev@gmail.com