函数式编程的初次见面

vlambda
2021-03-18

函数式编程的初次见面

 function double(arrIn) { let arrOut = []; for (let i = 0; i < arrIn.length; i++) { arrOut[i] = arrIn[i] * 2; } return arrOut; }

 function increment(arrIn) { let arrOut = []; for (let i = 0; i < arrIn.length; i++) { arrOut[i] = arrIn[i] + 1; } return arrOut; }

 function foo(arrIn) { return increment(double(arrIn)); }
 foo([1,2,3])

上边的三个函数，进行优化后

 let double = (arrIn)=>arrIn.map((item) => item * 2); let increment= (arrIn)=>arrIn.map((item) => item + 1);  let foo = (arrIn)=>increment(double(arrIn));

发现了组合函数，最终结果

 let double = (arrIn)=>arrIn.map((item) => item * 2); let increment= (arrIn)=>arrIn.map((item) => item + 1); let foo = (f, g) => (x => f(g(x))); foo(increment,double)([1,2,3])