The parts of the action method

method if_stmt($/) {
    my $past := PAST::Op.new(
                  $( $<expression> ),    # condition
                  $( $<statement> ),     # eval if true
                  :pasttype('if')
                );
    make $past;
}

• $/ is the node representing the if_stmt just matched
• $past becomes the newly created PAST::Op node
• $<expression> is the parse tree of the expression
• $( $<expression> ) is the AST of the expression
• "make $past" sets the AST for the if_stmt node