Nicholas Clark 提到:
So if the semicolon is replaced with a comma, like this,
my @x := [{1+1}, {2+2}];
the {} acts as a hash constructor, and @x is [{2 => undef}, {4 => undef}] ?
No, {} acts as a closure constructor, and @x contains two closures that
returns 2 and 4 respectively when called:
@x[0](); # 2
@x[1](); # 4
Basically, {} is only a hash constructor if the inside is either empty,
or contains only a list starting with a pair or a hash:
$hash = { };
$hash = { %stuff };
$hash = { "a" => 1 };
$hash = { "a" => 1, $b, $c, %stuff, @nonsense };
$code = { ; };
$code = { @stuff };
$code = { "a", 1 };
$code = { "a" => 1, $b, $c ==> print };
The examples above are from L<S04/"Statement parsing">.
Cheers,
Audrey
