withSyntax with repeaters

withSyntax.js

macro withSyntax_unzip {
    case { _ $name ($ps ...) ($es ...) ($p = $e:expr , $rest ...) $body } => {
        return #{
            withSyntax_unzip $name ($ps ... ($p)) ($es ... ($e)) ($rest ...) $body
        }
    }
    case { _ $name ($ps ...) ($es ...) ($p = $e:expr) $body } => {
        return #{
            withSyntax_unzip $name ($ps ... ($p)) ($es ... ($e)) () $body
        }
    }
    case { _ $name ($ps ...) ($es ...) ($p $punc = $e:expr , $rest ...) $body } => {
        var punc = #{$punc};
        if (punc[0].token.type !== parser.Token.Punctuator ||
            punc[0].token.value !== '...') {
            throwSyntaxError('withSyntax', 'Unexpected token', punc);
        }
        return #{
            withSyntax_unzip $name ($ps ... ($p $punc)) ($es ... ($e)) ($rest ...) $body
        }
    }
    case { $name ($ps ...) ($es ...) ($p $punc = $e:expr) $body } => {
        var punc = #{$punc};
        if (punc[0].token.type !== parser.Token.Punctuator ||
            punc[0].token.value !== '...') {
            throwSyntaxError('withSyntax', 'Unexpected token', punc);
        }

        return #{
            withSyntax_unip $name ($ps ... ($p $punc)) ($es ... ($e)) () $body
        }
    }
    case { _ $name ($ps ...) ($es ...) () $body } => {
        var name = #{$name};
        var here = #{here};
        var res = [makeIdent('syntaxCase', name)];
        var args = #{[$(makeDelim('()', $es)) (,) ...],};

        args = args.concat(makeIdent('context', name));
        res = res.concat(makeDelim('()', args, here));
        res = res.concat(#{
            { case { $ps ... } => $body }
        });

        return [makeDelim('()', res, here),
                makePunc('.', here),
                makeIdent('result', here)];
    }
}

let withSyntax = macro {
    case { $name ($vars ...) {$body ...} } => {
        return #{
            withSyntax_unzip $name () () ($vars ...) {$body ...}
        }
    }
}