my $thing = 'foo/bar/goo';
( my $stuff ) = ( $thing =~ 
    m{                # Quote-like characters are now {}.
        ^             # Match at the start of the string.
        ( [^/]+ )     # Capture everything in the set of all
                      # characters that are not '/'
    }x                # Close the regexp. x modifier allows
                      # freeform (as in non-significant
                      # whitespace).
);
print "$stuff\n";