[Functional Programming] Daggy

const daggy = require('daggy');
const {tagged, taggedSum} = daggy;


const Coord = daggy.tagged('Coord', ['x', 'y', 'z'])
const Line = daggy.tagged('Line', ['from', 'to'])

Coord.prototype.translate = function(x, y, z) {
    return Coord(
        this.x + x,
        this.y + y,
        this.z + z
    )
}
const origin = Coord(1,2,3)
console.log(origin); // { x: 1, y: 2, z: 3 }
const myLine = Line(
    origin,
    origin.translate(2,4,6)
);
console.log(myLine) // { from: { x: 1, y: 2, z: 3 }, to: { x: 3, y: 6, z: 9 } }


const Shape = taggedSum('Shape', {
    Square: ['topleft', 'bottomright'],
    Circle: ['centre', 'radius']
})

Shape.prototype.translate = function(x, y, z) {
    return this.cata({
        Square: (topleft, bottomright) => Shape.Square(
            topleft.translate(x, y, z),
            bottomright.translate(x, y, z)
        ),
        Circle: (centre, radius) => Shape.Circle(
            centre.translate(x, y, z),
            radius
        )
    })
}

console.log(Shape.Square(Coord(2, 2, 0), Coord(3, 3, 0))
    .translate(3, 3, 3))
// Square(Coord(5, 5, 3), Coord(6, 6, 3))

console.log(Shape.Circle(Coord(1, 2, 3), 8)
    .translate(6, 5, 4))
// Circle(Coord(7, 7, 7), 8)

All the tagged function really does is give us a function to fill the given named properties on an object.

taggedSum is a combination of multi Typed class.