TypeScript 5.0 - Hackdot

Re:TypeScript 5.0 by throwaway09432 on Thursday March 16, 2023 @09:45PM (#35191783)

Typescript is a good try, but ultimately our favourite JS runtime errors still happen, even with all the strictest ts settings. Syntactically it is quite clumsy, you can see the uninspired mix of C++ and Java in there. The typings now although people are doing lots of cute things with them, don't do some really fundamental things. For example there is currently no sensible way to type a non empty array in Typescript. Also the discriminated union with the identifying string literal in there is not terribly elegant.

Personally I wish either Rescript or Purescript gained adoption instead.

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Re:TypeScript 5.0 by NoInkling on Thursday March 16, 2023 @11:32PM (#35192671)

> there is currently no sensible way to type a non empty array in Typescript

If we remove the "sensible" requirement:

    type NonEmptyArray = [any, ...any[]]

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Re:TypeScript 5.0 by triyambakam on Friday March 17, 2023 @01:59PM (#35200531)

Or better:

    type NonEmptyArray = [unknown, ...unknown[]];
    const nea: NonEmptyArray = [];
    //    ^^^ Type '[]' is not assignable to type 'NonEmptyArray'.
    //        Source has 0 element(s) but target requires 1.

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Re:TypeScript 5.0 by throwaway09432 on Saturday March 18, 2023 @01:30AM (#35206420)

Can you map over this and preserve the NonEmptyArray type?

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Re:TypeScript 5.0 by triyambakam on Sunday March 19, 2023 @03:00AM (#35216711)

Do you mean pass in a type?

    type NonEmptyArray<T> = [T, ...T[]];

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Re:TypeScript 5.0 by throwaway09432 on Sunday March 19, 2023 @09:00AM (#35218504)

I mean if I have a NonEmptyArray say xs, and I then xs.map(x=>2*x), will the result of this expression be a NonEmptyArray ?

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Re:TypeScript 5.0 by triyambakam on Tuesday March 21, 2023 @08:28PM (#35254947)

No, unfortunately it will just be number[] as the return type.

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