JavaScript Pattern Matching Proposal

Post by edflsafoiewq » Thu, Apr 26, 2018, 2:58 PM UTC

LOLCAT1024 wrote: post #228

edflsafoiewq wrote: post #162

Earlier quoted context omitted.

Can you elaborate? What do you mean "match objects by their fields"? How does the proposal not already do that?

Maybe I did not express my self correctly, what I meant was - in it's current state the proposal rquires, when matching against an object, to specify all it's fileds, say you have an object with keys a, b, c then even if you match soley against the values of a , b you are required to specify c and by doing so notify it's existence. This poses a problem , since if you now remove c or add a filed d then the match will…

Post by kreas » Thu, Apr 26, 2018, 4:20 PM UTC

chc wrote: post #141

christophilus wrote: post #125

Earlier quoted context omitted.

> But a large percentage of JS developers don't really have much background in non-mainstream languages or programming language theory Not to side-track the issue, but I keep hearing this. I'm wondering if this is true, and if so, how such a statement is verified. I'm currently a full-time JS dev, but have written my own programming languages, have professionally written in C, C++, C#, F#, Ruby, and others, and have…

I think you're a super anomalous member of any programming language's community. I doubt even one programmer in a thousand has written F# professionally (not being hipster here — I haven't done it myself).

Post by codedokode » Thu, Apr 26, 2018, 5:47 PM UTC

Prefinem wrote: post #84

codedokode wrote: post #53

Earlier quoted context omitted.

By the way, I don't think it is a good idea to write a function as a constant. Please compare this function getDate(date) { .. } to this: const getDate = (date) => { ... } The first version is more readable. We instantly see that it is a function and in a second case it looks like a constant at first. Also without the equal and arrow sign it looks simpler.

Life is more fun with fat arrows sometimes new Promise(function (resolve, reject) { methodOne(data, function (error, response) { if (erorr) { reject(error); } else { resolve(response); } }) }) vs new Promise((resolve, reject) => methodOne(data, (error, response) => error ? reject(error) : resolve(response)));

    var numbers = [1, 2, 3, 4].map(x => x * x);
    var bestUsers = users.filter(u => u.getRating() > 100);

    var deferred = new Deferred;

    methodOne(data, function (error, response) {
        if (erorr) {
            deferred.reject(error);
        } else {
            deferred.resolve(response);
        }
    });

    return deferred.getPromise();

Post by codedokode » Thu, Apr 26, 2018, 5:54 PM UTC

Zacru wrote: post #174

codedokode wrote: post #53

Earlier quoted context omitted.

By the way, I don't think it is a good idea to write a function as a constant. Please compare this function getDate(date) { .. } to this: const getDate = (date) => { ... } The first version is more readable. We instantly see that it is a function and in a second case it looks like a constant at first. Also without the equal and arrow sign it looks simpler.

But function getDate(date) is hoisted. The const version isn't.

Post by Prefinem » Thu, Apr 26, 2018, 6:04 PM UTC

codedokode wrote: post #245

Prefinem wrote: post #84

Earlier quoted context omitted.

Life is more fun with fat arrows sometimes new Promise(function (resolve, reject) { methodOne(data, function (error, response) { if (erorr) { reject(error); } else { resolve(response); } }) }) vs new Promise((resolve, reject) => methodOne(data, (error, response) => error ? reject(error) : resolve(response)));

Yes, there are cases when arrow functions are useful: when small functions are used inline, like this: var numbers = [1, 2, 3, 4].map(x => x * x); var bestUsers = users.filter(u => u.getRating() > 100); But for a case when you have a large non-anonymous function, `function` keyword suits better. You don't need to use `const` keyword just becase it is something trendy now. In your example, the code with arrow function…

    const run = async () => {
        const response = await new Promise((resolve, reject) => methodOne(data, (e, res) => e ? reject(e) : resolve(res)));
    };

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