$_ =~ s/^&(\w+)([\(\)]*)/$1()/;

##</code><code>##

&foobar("asdf") # will only match &foobar(

##</code><code>##

s/^(&\w+)\(?((?:(?!;).)*)\)?;/$1($2);/

##</code><code>##

&foobar("a", 5, qw(dave jen anne matt), map({tr/[a-z]/[A-Z]/; $_;} @mixedCase));