"Perl Programmers Reference Guide (англ.) (программ.) /19.12.1998/ " - читать интересную книгу автора

and here's another.
THAT

Just don't forget that you have to put a semicolon on the
end to finish the statement, as Perl doesn't know you're
not going to try to do this:

print < 179231
ABC
+ 20;


LLLLiiiisssstttt vvvvaaaalllluuuueeee ccccoooonnnnssssttttrrrruuuuccccttttoooorrrrssss

List values are denoted by separating individual values by
commas (and enclosing the list in parentheses where
precedence requires it):

(LIST)

In a context not requiring a list value, the value of the
list literal is the value of the final element, as with
the C comma operator. For example,

@foo = ('cc', '-E', $bar);

assigns the entire list value to array foo, but

$foo = ('cc', '-E', $bar);

assigns the value of variable bar to variable foo. Note
that the value of an actual array in a scalar context is
the length of the array; the following assigns the value 3
to $foo:

@foo = ('cc', '-E', $bar);
$foo = @foo; # $foo gets 3

You may have an optional comma before the closing
parenthesis of a list literal, so that you can say:

@foo = (
1,
2,
3,
);

LISTs do automatic interpolation of sublists. That is,
when a LIST is evaluated, each element of the list is