If I can tco a named recursive function there should be a way to tco anonymous recursive function.If there is a way please explain how to do this below is my recursive function and TCO function.
function recursive(length, callback) {
tco((function (i, sum) {
var args = arguments;
if (i > length) {
console.log("break statement");
callback(sum)
return sum
} else {
return args.callee(i + 1, sum + i)
}
}))(0, 0)
}
function tco(f) {
var value;
var active = false;
var accumulated = [];
return function accumulator() {
accumulated.push(arguments);
if (!active) {
active = true;
while (accumulated.length) {
value = f.apply(this, accumulated.shift());
}
active = false;
return value;
}
}
}
ES6 proposes changes to the tail-call system, an engine optimization. A tail-call is when a function is called as the last statement in another function, like this:
function doSomething() {
return doSomethingElse(); // tail call
}
ECMAScript 6 seeks to reduce the size of the call stack for certain tail calls in strict mode. With this optimization, instead of creating a new stack frame for a tail call, the current stack frame is cleared and reused so long as the following conditions are met :
Perhaps the hardest situation to avoid is in using closures. Because a closure has access to variables in the containing scope, tail call optimization may be turned off. For example:
"use strict";
function doSomething() {
var num = 1,
func = () => num;
// not optimized - function is a closure
return func();
}
Consider this function, which computes factorials:
"use strict";
function factorial(n) {
if (n <= 1) {
return 1;
} else {
// not optimized - must multiply after returning
return n * factorial(n - 1);
}
}
In order to optimize the function, you need to ensure that the multiplication doesn't happen after the last function call.
"use strict";
function factorial(n, p = 1) {
if (n <= 1) {
return 1 * p;
} else {
let result = n * p;
// optimized
return factorial(n - 1, result);
}
}
Source: An Awesome book by Nicholas Zakas, Understanding ECMAScript 6.
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