$use StdIO;

$func Perm e1 c2 = ;

Perm {
  e1 [t2] = <WriteLN e1 t2>;
  e1 [t2]+c3, <Perm e1 t2 c3>, $fail;
  e1 c2 = /*empty*/;
}

Main = <Perm [1,2,3,4]>;