fantasia/src/coyoneda.js

Free yourself in the land of fantasies.

var combinators = require('fantasy-combinators'),
    daggy = require('daggy'),

    compose = combinators.compose,
    identity = combinators.identity,

    Coyoneda = daggy.tagged('f', 'x');

Coyoneda.lift = function(x) {
    return Coyoneda(identity, x);
};

Coyoneda.prototype.map = function(f) {
    return Coyoneda(compose(f)(this.f), this.x);
};

Coyoneda.prototype.lower = function() {
    return this.x.map(this.f);
};

// Export
if (typeof module != 'undefined')
    module.exports = Coyoneda;