nominal VS ts-toolbelt

Hey OP here, Wanted to share something we recently discovered in typescript. This is a way to to create haskell style Newtype using the lesser known \`symbols\` ```ts type Minutes = number type Seconds = number const minutesToSeconds = (minutes: Minutes) => minutes * 60 const seconds: Seconds = 420 // uh-oh, we can use Minutes and Seconds interchangeably minutesToSeconds(seconds) ``` Nominal types solve this problem ```ts import { Nominal, nominal } from 'nominal-types'; type Minutes = Nominal<'Minutes', number>; type Seconds = Nominal<'Seconds', number>; const minutesToSeconds = (minutes: Minutes) => minutes * 60 // You can directly type cast or use nominal.make const seconds = nominal.make(420) const minutes = 1337 as Minutes // doesn't work, yay type safety minutesToSeconds(seconds) // does work! minutesToSeconds(minutes) ``` We have some lot cooler examples https://github.com/modfy/nominal#examples You can also read more about it here: https://zackoverflow.dev/writing/nominal-and-refinement-types-typescript

There are a bunch of awesome type utility libraries that may boost your works on types, like ts-toolbelt, utility-types, SimplyTyped, etc., which you can already use.

We have only scratched the surface of type manipulation in Typescript, if you want to get your mind blown, checkout community projects like ts-toolbelt and type-challenges.

Do you mean https://github.com/millsp/ts-toolbelt? You didn’t provide a link so I’m not sure which repo you’re referring to.

I am guessing that since it does not exists as an built in type, in utility-types, or in ts-toolbelt that it currently isn't possible.

Since posting this, some comments have made me aware that ts-toolbelt has this feature and a couple other really useful ones built in. So their source code could be worth skimming through to see how they did things.

I was curios enough to dug the definition along with a related types Narrowable and Cast

ts-toolbelt has a "Path" Type https://github.com/millsp/ts-toolbelt