replace s///r ?

[Marc Chantreux]

hello people,

in perl5, i can

        print for
            map  s/^/4/r,
            grep /^\d+$/,
            <ARGV>

the perl6 version is a Seq, so much more memory friendly
but i expected (and haven't found in the documentation)
a short equivalent of s///r so the shorter i have is:

    $*ARGFILES
     . lines
     . grep( / ^ <digit>+ $ / )
     .  map( *.subst(/^/," * ") )
     .  map(&other-things-to-do)
     .  map(&say)

when, of course, i want to replace

     .  map( *.subst(/^/," * ") )

by something like

     .  map( s:r/^/* / )

any idea?

regards
marc