Re^4: Why? (each...)

In the current context, they definitely do NOT create a list. They override the relative precedence of the comma and assignment operators.

my %keys = (A => "b");
            -    ---
            1     2     List has two items
[download]

my %keys = A => "b";
------------    ---
     1           2      List still there without parens
[download]

Parens never create a list as far as I'm concerned, but people have debated me on two specific cases:

In some places where a list is already being created, «()» is needed to indicate the list contains no elements. The parens don't create the list (since it would also get created if one used «@a» instead of «()»), they simply indicate the list is empty.
In some places, the presence of parens affect the choice of operator to one that creates a list. (e.g. «$x = f();» vs «($x) = f();»). It's actually the assignment operator (not the parens) that creates the list as is gets created for «@a = f();» as well. Although both indirectly create a list, it makes no sense to say that parens create a list since noone says "«@a» creates a list".

Parens, curlies and square brackets have other uses than those I described, of course, but I doubt the other uses create confusion.

Lists value are created by operators that always take a list (e.g. foreach, list assignment, function calls, etc), and list literals are created by the comma operator.

foreach ($x) { }     @a = @b;     f $x;
         ^^          ^^   ^^        ^^
        list        list  list     list
        value      value  value    value

$i, $j;     @a = ($i, $j);
^^^^^^      ^^   ^^^^^^^^
 list      list  list value
literal   value  (from list literal)
[download]

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Re^5: Why? (each...) by Argel (Prior) on May 12, 2011 at 23:15 UTC
I was thinking of two things: when "()" is used to indicate you want or have an empty list, and then more for reading source code, where parens often indicate to the reader that he is looking at a list. The parens in foreach(), my($x,$y,$z)=@_, etc. Or e.g. in the case of %hash=(x=>"a",y="b") the parens indicate a list of key/value pairs. Or to put it differently, they indicate it's not an array and not a hash (and not a scalar). Elda Taluta; Sarks Sark; Ark Arks	[reply]
Re^6: Why? (each...) by ikegami (Patriarch) on May 12, 2011 at 23:53 UTC
where parens often indicate to the reader that he is looking at a list. You say foreach (), I say while () and if (). You say `my ($x,$y,$z) = @_;`, I say `($x+$y+$z)$n`. The parens in foreach(),* The parens of `foreach` not even part of the expression, and the list is still created when you omit them. `say foreach "a", "b";` [download] Or to put it differently, they indicate it's not an array and not a hash (and not a scalar). Really? `$s = ($x); %h = ($x); %h = ([]);` [download] Your model has too many holes to count :( Simple model: A list is created whenever something is evaluated in list context.	[reply] [d/l] [select]
Re^7: Why? (each...) by LanX (Saint) on May 13, 2011 at 00:06 UTC
>The parens of foreach not even part of the expression, and the list is still created when you omit them. `say foreach "a", "b";` Well, you know that postfix-commands follow different syntax rules! Cheers Rolf	[reply] [d/l]
Re^8: Why? (each...) by ikegami (Patriarch) on May 13, 2011 at 00:13 UTC
Re^9: Why? (each...) by Argel (Prior) on May 13, 2011 at 18:37 UTC
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