TypeScript 3.5

Post by phillipcarter » Thu, May 30, 2019, 1:02 AM UTC

phiresky wrote: post #11

sli wrote: post #2

I would really love to enjoy TypeScript, especially now that they've added HKTs, but I am constantly running into type errors when the types clearly match, leading to weird workaround code where the type of some key in some object is specified as: false | 'x' | 'y' | undefined Meaning passing in `'x'` should work just fine. But instead, it specializes it to just a string, then throws a type error. The workaround requ…

> in many cases being unable to import a JS library in that doesn't include typedefs Make sure you have "allowJs": true in your tsconfig.json. Otherwise, you'll have to create a minimal file with `declare module "xyz";` > I fail to see how TS can be considered a superset of JS You have to interpret all TS "errors" as warnings for that to be true (which they mostly are considering tsc still emits code regardless of no…

Post by negativegate » Thu, May 30, 2019, 1:35 AM UTC

hajile wrote: post #49

IceDane wrote: post #23

Earlier quoted context omitted.

I can't downvote you but I want to point out that the only thing you accomplish with such a comment is coming off as ignorant and bitter. I have no idea why on Earth you think the type system is broken. Objectively, it simply isn't, obviously, but I'd love to see you trip over your own feet trying to argue that it is. Moreover, it's honestly remarkable how they've managed to retrofit such an amazing type system on to…

I don't know if 3.5 fixes this, but here's an example from 3.4 function messUpTheArray(arr: Array ): void { arr.push(3); } const strings: Array = ['foo', 'bar']; messUpTheArray(strings); const s: string = strings[2]; console.log(s.toLowerCase()) You obviously can't push a number into an Array , yet typescript allows it. For my money, ReasonML is a better solution for type issues (hindley-milner types are awesome).

Post by logicchains » Thu, May 30, 2019, 2:06 AM UTC

phillipcarter wrote: post #51

phiresky wrote: post #11

Earlier quoted context omitted.

> in many cases being unable to import a JS library in that doesn't include typedefs Make sure you have "allowJs": true in your tsconfig.json. Otherwise, you'll have to create a minimal file with `declare module "xyz";` > I fail to see how TS can be considered a superset of JS You have to interpret all TS "errors" as warnings for that to be true (which they mostly are considering tsc still emits code regardless of no…

> There is no other programming language that has union types as powerful as TypeScript I suggest looking into Idris and other languages with dependent types. Nothing against typescript, but it’s not even close.

Post by mattigames » Thu, May 30, 2019, 2:51 AM UTC

farnsworth wrote: post #56

mattigames wrote: post #52

The 2 big things missing on typescript: 1) Operator overloading 2) Runtime type checking of JSON payloads (on dev env at least) Can't believe in 2019 every library has to create its own way to add 2 elements of the same class together e.g dataframe1.addTo(dataframe2) vs dataframe1 + dataframe2 And the most common error that it should help catch during development is that you get a JSON and you cast it but it means no…

> 1) Operator overloading Please, please, please, no.

Post by jasonhansel » Thu, May 30, 2019, 3:58 AM UTC

Roboprog wrote: post #44

It sounds like type inference for object literals is coming along, even if there a few quibbles about some of the defaults on literals mentioned here. Did they ever get a solution in place for partial function application (e.g. - as for Ramda.js)? When this gets to the point where the only place I have to define explicit types is for JSON data read from the network, I’ll consider using it. I know I’m in the minority,…