arktype•4mo ago

Pipe required before narrow

const myFunc = (v: string) => true;
const MyString = type("50<string<200").narrow((s) => myFunc(s));

const myFunc = (v: string) => true;
const MyString = type("50<string<200").narrow((s) => myFunc(s));

Results in error:

error TS2345: Argument of type 'is<MoreThanLength<50> & LessThanLength<200>>' is not assignable to parameter of type 'string'.

error TS2345: Argument of type 'is<MoreThanLength<50> & LessThanLength<200>>' is not assignable to parameter of type 'string'.

However, adding pipe before calling narrow works:

const myFunc = (v: string) => true;
const MyString = type("50<string<200").pipe((s) => s).narrow((s) => myFunc(s));

const myFunc = (v: string) => true;
const MyString = type("50<string<200").pipe((s) => s).narrow((s) => myFunc(s));

Is this intentional?

4 Replies

ssalbdivad•4mo ago

No those branded types should never be inferred out like that. I'll fix it, thanks!

SynthLuvr•4mo ago

Also seems like I can't use two narrow in a row, I need to do narrow -> pipe -> narrow, with the pipe doing nothing more than return the value untouched

ssalbdivad•4mo ago

I'll see if I can get all these bug fixes merged today!

SynthLuvr•4mo ago

https://github.com/arktypeio/arktype/issues/969

GitHub

Cannot use narrow before pipe · Issue #969 · arktypeio/arktype

Report a bug 🔎 Search Terms narrow pipe 🧩 Context ArkType version: 2.0.0-dev.13 TypeScript version (5.1+): 5.3.3 Other context you think may be relevant (JS flavor, OS, etc.): 🧑‍💻 Repro const myFun...

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Pipe required before narrow