You know what the difference between -'foo' and '-foo' is? nothing

This could be a gotcha if you needed the + sign.

Sure, but why use the - in that case?

:) see Re: Why is this auto-quoted? (because) and perlglossary#identifier and nans, infs, and vomit

$ perl -wle " print +foo"
Unquoted string "foo" may clash with future reserved word at -e line 1
+.
Name "main::foo" used only once: possible typo at -e line 1.
print() on unopened filehandle foo at -e line 1.

$ perl -wle " print -+foo"
Unquoted string "foo" may clash with future reserved word at -e line 1
+.
-foo

$ perl -wle " print -'+foo'"
-foo

$ perl -wle " print -(-foo)"
+foo
[download]

This also works:

$perl -wle " print - -foo "
+foo
[download]

The space between the two minus signs is significant; otherwise Perl thinks you're trying to decrement a constant.

Also:

$perl -wle " print -+-foo "
+foo

$perl -wle " print +-+-foo "
+foo

$perl -wle " print -+-+-foo "
-foo

$perl -wle " print +-+-+-foo "
-foo

$perl -wle " print -+-+-+-foo "
+foo

$perl -wle " print +-+-+-+-foo "
+foo
[download]

...etc

package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name

Sure, but why use the - in that case?

You may not know there is a + there, as in an eval or "$interpolation".

-QM
--
Quantum Mechanics: The dreams stuff is made of