Instantly share code, notes, and snippets.

Embed
What would you like to do?
Fantas, Eel, and Specification
import { tagged } from "daggy";
const First = tagged("First", ["val"]);
First.prototype.concat = function(that) {
return this;
};
const Min = tagged("Min", ["val"]);
Min.prototype.concat = function(that) {
return Min(Math.min(this.val, that.val));
};
const Any = tagged("Any", ["val"]);
Any.prototype.concat = function(that) {
return Any(this.val || that.val);
};
const Tuple4 = tagged("Tuple4", ["a", "b", "c", "d"]);
Tuple4.prototype.concat = function(that) {
return Tuple4(
this.a.concat(that.a),
this.b.concat(that.b),
this.c.concat(that.c),
this.d.concat(that.d)
);
};
const Customer = tagged("Customer", [
"name",
"favouriteThings",
"registrationDate",
"hasMadePurchase"
]);
const myStrategy = {
to: customer =>
Tuple4(
First(customer.name),
customer.favouriteThings,
Min(customer.registrationDate),
Any(customer.hasMadePurchase)
),
from: ({ a, b, c, d }) => Customer(a.val, b, c.val, d.val)
};
const merge = strategy => x => y =>
strategy.from(strategy.to(x).concat(strategy.to(y)));
const Tom1 = Customer("Tom", ["socks"], 100000, false);
const Tom2 = Customer("TomH", ["gloves"], 90000, true);
// { name: 'Tom'
// , favouriteThings: ['socks', 'gloves']
// , registrationDate: 90000
// , hasMadePurchase: true
// }
merge(myStrategy)(Tom1)(Tom2);
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment