首页 > 代码库 > [JS Compose] 5. Create types with Semigroups
[JS Compose] 5. 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.
A semigroup is a type with a concat method. Let‘s see if we have a string A, we can concat that with the string B. String is the semigroup here because it has a concat method. If we log this out here, we shall see the results AB and there we are.
"a".concat("b").concat("c"); //"abc""a".concat("b".concat("c")); //"abc"
We can also define our own semi-group:
const Sum = x => ({ x, // we need to export x, so we can access it concat: o => Sum(o.x + x), // o -> Sum(x) toString: () => `Sum(${x})` });const res = Sum(1).concat(Sum(2));console.log(res.toString()); // Sum(3)
const All = x => ({ x, concat: o => All(o.x && x), toString: ()=> `All(${x})`});const res = All(true).concat(All(false));console.log(res.toString()); // All(false)
const First = x => ({ x, concat: o => First(x), toString: () => `First(${x})`});const res = First(true).concat(First(false));console.log(res.toString()); // First(true)
[JS Compose] 5. Create types with Semigroups
声明：以上内容来自用户投稿及互联网公开渠道收集整理发布，本网站不拥有所有权，未作人工编辑处理，也不承担相关法律责任，若内容有误或涉及侵权可进行投诉： 投诉/举报 工作人员会在5个工作日内联系你，一经查实，本站将立刻删除涉嫌侵权内容。