fix: preserve literal types in Infer by using const type parameter#7
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mhweiner merged 1 commit intologfoxai:mainfrom Jan 30, 2026
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- Change literal<T extends any> to literal<const T> for proper type inference
- Add type-level tests to verify literal types are preserved
- Add TypeScript 5.0+ requirement to README
- Add optional peerDependency on TypeScript >=5.0.0
The const type parameter modifier (TS 5.0+) prevents type widening,
so Infer<typeof literal('text')> now correctly produces 'text' instead of string.
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Use TypeScript 5.0's
consttype parameter modifier to preserve literal types through inference. Previously,literal('text')would infer asstringinstead of'text', breaking discriminated union narrowing.Before:
const v = literal('text');
type T = Infer; // string
After:
const v = literal('text');
type T = Infer; // 'text'
This removes the need for callers to use
as constat call sites.