Create types with Semigroups
An introduction to concatting items via the formal Semi-group interface. Semi-groups are simply a type with a concat method that are associative. We define three semigroup instances and see them in action.
Benji Shine
~ 7 years ago
Can you explain the {x: y} in the parameter to concat?
x,
concat: ({x: y}) =>
Sum(x + y),Is that the same x as on the line above it?
Benji Shine
~ 7 years ago
I think I understand, now that I've read the transcript:
I like to destructure this other Sum so why don't we say x and we'll assign it to y, and now we can just say x + y, much simpler. We are destructuring Sum type and just grabbing x off of it and calling it a y here. It should still work, and there we have it.
In the statement lots = Sum(3).concat(50) , the destructuring assignment makes the values be...
concat({x: y}) => {
// x is 3 and y is 50
return Sum(3 + 50);
}),This is just like saying:
const { x: y } = { x: 50 };
// now y = 50