New features

P.record patterns

To match a Record<Key, Value> (an object with consistent key and value types), you can use P.record(keyPattern, valuePattern). It takes a sub-pattern to match against the key, a sub-pattern to match against the value, and will match if all entries in the object match these two sub-patterns.

import { match, P } from 'ts-pattern';...

TS-Pattern v5.8.0 Release Notes

New Feature: .narrow() Method for Deep Type Narrowing

.narrow() gives you fine-grained control over type narrowing of deeply nested union types during pattern matching.

What is .narrow()?

The .narrow() method allows you to explicitly narrow the input type to exclude all values that have been handled by previous patterns. This is especial...

Type inference bug fixes

This new release fixes the following bug in exhaustiveness checking when matching on optional properties:

type Input = { type?: 'one' } | { type: 'two' };

const f1 = (input: Input) =>
  match(input)
    .with({ type: 'one' }, () => {})
    .with({ type: 'two' }, () => {})
    .exhaustive(); // shouldn't type-check, but does 👎


const f2 = (input:...

New feature

Exhaustive callback

By default, .exhaustive() will throw an error if the input value wasn't handled by any .with(...) clause. This should only happen if your types are incorrect.

It is possible to pass your own handler function as a parameter to decide what should happen if an unexpected value has been received. You can for example throw your own custom error:

What's Changed

• fix(isMatching): Fix non-object patterns by @gvergnaud in https://github.com/gvergnaud/ts-pattern/pull/307

Full Changelog: https://github.com/gvergnaud/ts-pattern/compare/v5.6.1...v5.6.2