[Ramda] Getter and Setter in Ramda & lens

Getter on Object:

1. prop:

R.prop('x', {x: }); //=> 100
R.prop('x', {}); //=> undefined

2. props:

R.props(['x', 'y'], {x: , y: }); //=> [1, 2]
R.props(['c', 'a', 'b'], {b: , a: }); //=> [undefined, 1, 2]

Setter ob Object:

R.assoc('c', , {a: , b: }); //=> {a: 1, b: 2, c: 3}

Another way to use Lens:

var xLens = R.lens(R.prop('x'), R.assoc('x'));

R.view(xLens, {x: , y: });            //=> 1
R.set(xLens, , {x: , y: });          //=> {x: 4, y: 2}