Thomas Sandlaß wrote: >> Or perhaps even >> >> sub foo (Num @in is copy does LinearInterpolation) >> { >> ... >> } > > > This is my big questionmark on roles: is the above a contraint > or merely a directive. In the former case only Arrays of Num that > do LinearInterpolation are allowed, in the latter case every > Array of Num that is used as argument gets the role attached while > it lingers in foo. Perhaps a new keyword/opertor is need to separate the constraints from the directives. C<that> would read nicely: sub foo ( Num @in is copy that does LinearInterpolation ) Dave.Thread Previous