arktype•2mo ago

arktype with isolatedDeclarations

If you have a package that uses arktype and isolatedDeclarations: true in tsconfig.json (for speed, OXC/tsdown support), then you'll likely see this error:

RollupError: TS9010: Variable must have an explicit type annotation with --isolatedDeclarations.
  x TS9010: Variable must have an explicit type annotation with
  | --isolatedDeclarations.
   ,-[/Users/eric/Projects/testdriverai/monorepo/packages/sdk/src/types.ts:7:14]
 6 | 
 7 | export const $ = type.scope({

RollupError: TS9010: Variable must have an explicit type annotation with --isolatedDeclarations.
  x TS9010: Variable must have an explicit type annotation with
  | --isolatedDeclarations.
   ,-[/Users/eric/Projects/testdriverai/monorepo/packages/sdk/src/types.ts:7:14]
 6 | 
 7 | export const $ = type.scope({

Is there a way to explicitly provide a return type annotation without redeclaring the whole thing?

7 Replies

ssalbdivad•2mo ago

No, you'll run into this problem with any library with schema inference. It's inherently in conflict with isolatedDeclarations, which is why I don't recommend that setting unless you're a really large project with very few dependencies that rely on inference and have a ton of tolerance for repetitive declarations to help somewhat improve compilation speed.

EricOP•2mo ago

Good to know. You’re right. Didn’t know if there was a “simple” answer. There probably is one, and that’s to use tsup or zshy in Arktype projects, not tsdown 😅

ssalbdivad•2mo ago

I'm sitting next to Colin right now he recommends zshy 👍

EricOP•2mo ago

lol, I have both - I needed to inline some private packages which means ✨ bundle ✨ Tell Colin I said hi! And that turbo watch build should close a few open issues 🙏 Where you at? Some coffee shop someplace? Wait, hang on. OR Did he come to your place because of all the snarky Zod tweets you made!?

ssalbdivad•2mo ago

Yeah it's a beatdown

ssalbdivad•2mo ago

We are at Squiggle Conf https://squiggleconf.com/

SquiggleConf 2025 | Supercharging web devs and their tools

A Boston conference for excellent web dev tooling.

EricOP•2mo ago

Oh, cool! I've yet to go. Money's tight af here 🙁

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arktype with isolatedDeclarations

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