Arguments to subrules

start:   word  rev[$item[1]]  {1}

rev:     word  {$return = 1 if $arg [0] eq reverse $item [1]; undef}

word:    /\w+/

In [1] := foo oof
Out [1] = 1
In [2] := foo bar
Out [2] = <<UNDEF>>

• Subrules can be called with arguments.
• Arguments are places inside square brackets.
• The arguments are in the subrule available as @arg or as %arg.
• Both @arg and %arg are always available - one is free to use whatever method one prefers.
• Arguments come before repetition specifier: rule: sub other[$item[1]](s)