supertransformer.js

var rules = [ // WIP
    // trim value white space
    [,/^ +| +$/g,''],
    // cast to boolean
    ['featured',, Boolean],
    // cast to date
    ['lastupdate',, Date]].map(transform);

Catalog(someObject, orArraysThereof);

/*
┌─┐┌─┐┌┬┐┌─┐┬  ┌─┐┌─┐
│  ├─┤ │ ├─┤│  │ ││ ┬
└─┘┴ ┴ ┴ ┴ ┴┴─┘└─┘└─┘ */
function Catalog(...items){
    return items.reduce((catalog), {});

    function catalog(dict, item){
        for (let [key, value] of Object.entries(item)){
            let initial = key in dict? dict[key]: new Map;
            switch (value.constructor.name){
                case 'Array':
                    dict[key] = value.reduce(catalog, initial);
                    break;
                case 'Object':
                    dict[key] = [value].reduce(catalog, initial);
                    break;
                default:
                    dict[key] = archive(initial, value, item);
                    break;
            }
        }
        return dict;

        function archive(context, key, item){
            context[key] = key in context ?
                [item].concat(context[key])
                : [item];
            return context;
        }
    }
}

//WIP
function transform(rules){
    var [l, r, lambda] = rules;
    return rules.map(function(rule){
        
        return function(key, value){
            return [key, value];
        }
    });
}
//WIP
function reductor(tuple, fn){
    //console.warn(tuple[0], tuple[1]);
    return tuple;
}

// II. transform by key pattern
// 1. featured: Boolean
// 2. lastupdate: Date
// 3. owner: Person
// 4. url: protocol, host, port, pathname, search, hash
// 5. type: Navigation