map(($_ => 2*$_), @list)
map +($_ => 2*$_), @list
map { $_ => 2*$_ } @list

##</code><code>##

map(($_ => 2*$_), @list)

##</code><code>##

map ($_ => 2*$_), @list   # XXX

##</code><code>##

map(($_ => 2*$_), ()), @list   # XXX

##</code><code>##

map +($_ => 2*$_), @list