Perl 6 expression parser

expr.pl

grammar Expr {
    token number { \d+ {*} }

    token operator { <op> {*} }
    proto token op { <...> }
    token op:sym<+> { <sym> }
    token op:sym<-> { <sym> }
    token op:sym<*> { <sym> }
    token op:sym</> { <sym> }

    rule expr { <number> [ <operator> <expr> ]? {*} }
    rule TOP { ^<expr>$ }
}

class ExprEval {
    has %.ops = {
        '+' => &infix:<+>,
        '-' => &infix:<->,
        '*' => &infix:<*>,
        '/' => &infix:</>,
    };

    method expr($/) {
        if $/<operator> {
            my $op = $/<operator>[0].ast;
            make $op($/<number>.ast, $/<expr>[0].ast);
        } else {
            make $/<number>.ast;
        }
    }

    method TOP($/) { make $/<expr>.ast }
    method number($/) { make +$/ }
    method operator($/) { make %.ops{~$/<op><sym>} }
}

my $parse = Expr.parse("3 + 1 + 2", :actions(ExprEval.new)) || "unparsable";
say $parse.ast;