TypeScript 5.0

Post by RyanCavanaugh » Thu, Mar 16, 2023, 7:21 PM UTC

throw_m239339 wrote: post #91

dimitropoulos wrote: post #2

Without Angular, we may very well not have TypeScript today. The top thing listed in this release (TypeScript doesn't follow semver, btw) is about Decorators. I find the whole story about Angular's role in TypeScript early days to be very fascinating because I don't hear people talk about it anymore (just search "AtScript TypeScript" if you weren't around at the time). It was the Angular team that forced Decorators t…

> Without Angular, we may very well not have TypeScript today. Typescript was started at Microsoft by the guy who designed Turbo Pascal and C#, so completely independently from Google's Angular team. Angular had its own "AtScript" and eventually ditched that. Typescript had experimental decorator support well before Angular Team moved from AtScript, because it was a ECMAScript proposal. Angular had zero influence in…

Post by explaininjs » Thu, Mar 16, 2023, 7:22 PM UTC

benatkin wrote: post #62

RyanCavanaugh wrote: post #55

Earlier quoted context omitted.

In TypeScript, type guards are considered to be exhaustive, so if you have a string | number and check it against a function that says it returns "x is number", then TypeScript will think that in the negative case, it's a string. If isInteger was marked as a type guard, then you could write code like this: function f(s: string | number) { if (!Number.isInteger(s)) { console.log(s.substring(0, 0)); } } which is clearl…

That seems like an important feature request. I see TypeScript adding fancy stuff without fixing core limitations.

    const intSymbol = Symbol('integer')
    type integer = number & {[intSymbol]: never}

    const isInteger = (n: unknown): n is integer => Number.isInteger(n)

    function f(s: string | number) {
        if (isInteger(s)) {
            const allowed = s.toExponential()
        } else {
            // s still string | number
        } 
    }

Post by nosianu » Thu, Mar 16, 2023, 7:24 PM UTC

pjmlp wrote: post #93

I wonder when will be Typescript done, there is only so much that one can do adding a type system to JavaScript, without starting to become C++ like complexity language, which arguably already is.

Post by hackandthink » Thu, Mar 16, 2023, 7:27 PM UTC

endisneigh wrote: post #50

I have a strange take - I think Typescript types are better most other languages, including Java, C++ and Go. It's strange since TypeScript is adding types to a weakly typed language. If we could push JavaScript performance to be another order of magnitude faster it wouldn't be necessary to use other languages, imho. Of course, pushing it that far without effectively creating a new one would be difficult, to say the…

Post by felipeccastro » Thu, Mar 16, 2023, 7:31 PM UTC

spion wrote: post #87

endisneigh wrote: post #50

I have a strange take - I think Typescript types are better most other languages, including Java, C++ and Go. It's strange since TypeScript is adding types to a weakly typed language. If we could push JavaScript performance to be another order of magnitude faster it wouldn't be necessary to use other languages, imho. Of course, pushing it that far without effectively creating a new one would be difficult, to say the…

I used to think so too, until I tried Rust. By comparison, JavaScript (and by extension, TypeScript) is still lacking fundamental features and the library ecosystem situation is pretty bad. I wish there was a modern language that took all the good non-manual-memory-management things from Rust and added a GC and some immutable data structures. Error handling, enums, macros (with compile_error! / diagnostics API), trai…