v5.6.0

This release contains two changes:

Typecheck pattern when using isMatching with 2 parameter.

It used to be possible to pass a pattern than could never match to isMatching. The new version checks that the provide pattern does match the value in second parameter:

type Pizza = { type: 'pizza'; topping: string };
type Sandwich = { type: 'sandwich'; condiments: string[] };
type Food = Pizza | Sandwich;

const fn = (food: Pizza | Sandwich) => {
    if (isMatching({ type: 'oops' }, food)) {
        //                  👆 used to type-check, now doesn't!
    }
}

Do not use P.infer as an inference point

When using P.infer<Pattern> to type a function argument, like in the following example:

const getWithDefault = <T extends P.Pattern>(
  input: unknown,
  pattern: T,
  defaultValue: P.infer<T> //  👈
): P.infer<T> =>
  isMatching(pattern, input) ? input : defaultValue

TypeScript could get confused and find type errors in the wrong spot:

const res = getWithDefault(null, { x: P.string }, 'oops') 
//                                     👆           👆 type error should be here
//                                 but it's here 😬

This new version fixes this problem.

What's Changed

• Improvements to P.infer and isMatching by @gvergnaud in #302
• build(deps-dev): bump rollup from 2.79.1 to 2.79.2 by @dependabot in #289

Full Changelog: v5.5.0...v5.6.0

v5.5.0

What's Changed

• Export Pattern types in package.json by @GGomez99 in #292 closing issue #291

New Contributors

• @GGomez99 made their first contribution in #292

Full Changelog: v5.4.0...v5.5.0

v5.4.0

The main thing — Faster type checking 🚀

This release brings a significant perf improvement to exhaustiveness checking, which led to a ~16% decrease in the time to type-check the full test suite of TS-Pattern:

Category	Before	After	Evolution (%)
Instantiations	6,735,991	4,562,378	-32.33%
Memory used	732,233K	746,454K	1.95%
Assignability cache size	209,959	205,926	-1.92%
Identity cache size	28,093	28,250	0.56%
Check time	5.78s	4.83s	-16.44%

What's Changed

• build(deps-dev): bump braces from 3.0.2 to 3.0.3 by @dependabot in #273
• build(deps-dev): bump webpack from 5.91.0 to 5.94.0 in /examples/gif-fetcher by @dependabot in #276
• build(deps): bump serve-static and express in /examples/gif-fetcher by @dependabot in #283
• perf: improve type checking performance of BuildMany by @gvergnaud in #286
• Fixes type InvertPatternForExcludeInternal to work with readonly array by @changwoolab in #284

New Contributors

• @changwoolab made their first contribution in #284

Full Changelog: v5.3.1...v5.4.0

v5.3.1

Pattern-matching on symbol keys

Symbols used to be ignored in object patterns. They are now taken into account:

const symbolA = Symbol('symbol-a');
const symbolB = Symbol('symbol-b');

const obj = { [symbolA]: { [symbolB]: 'foo' } };
    
if (isMatching({ [symbolA]: { [symbolB]: 'bar' } }, obj)) {
   //  👆 Used to return true, now returns false!
   
   //  Since TS-Pattern wasn't reading symbols, this pattern used to be equivalent
   //  to the `{}` pattern that matches any value except null and undefined.
}

.exhaustive now throws a custom error

People have expressed the need to differentiate runtime errors that .exhaustive() might throw when the input is of an unexpected type from other runtime errors that could have happened in the same match expression. It's now possible with err instanceof NonExhaustiveError:

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

const fn = (input: string | number) => {
  return match(input)
    .with(P.string, () => "string!")
    .with(P.number, () => "number!")
    .exhaustive()
}

try {
  fn(null as string) // 👈 💥 
} catch (e) {
  if (e instanceof NonExhaustiveError) {
    // The input was invalid
  } else {
    // something else happened
  }
}

What's Changed

• build(deps-dev): bump braces from 3.0.2 to 3.0.3 in /examples/gif-fetcher by @dependabot in #262
• feat: throw custom ExhaustiveError when no matched pattern by @adamhamlin in #270
• Symbols as keys by @Ayc0 in #272

New Contributors

• @adamhamlin made their first contribution in #270
• @Ayc0 made their first contribution in #272

Full Changelog: v5.2.0...v5.3.1

v5.2.0

The main thing

new P.string.length(n) pattern

P.string.length(len) matches strings with exactly len characters.

const fn = (input: string) =>
  match(input)
    .with(P.string.length(2), () => '🎉')
    .otherwise(() => '❌');

console.log(fn('ok')); // logs '🎉'

What's Changed

• docs: fix typo in P.when patterns code example by @grigorischristainas in #260
• feat: Added P.string.length by @JUSTIVE in #257

New Contributors

• @grigorischristainas made their first contribution in #260

Full Changelog: v5.1.2...v5.2.0

v5.1.2

The main thing

When combining P.nonNullable and P.nullish, you should get an exhaustive pattern matching expression, but the following case was incorrectly considered non-exhaustive:

declare const input: {
  nested: string | number | null | undefined;
};

const res = match(input)
  .with({ nested: P.nonNullable }, (x) => {/* ... */})
  .with({ nested: P.nullish }, (x) => {/* ... */})
  // should type-check
  .exhaustive();

This is fixed now.

What's Changed

• build(deps): bump postcss and react-scripts in /examples/gif-fetcher by @dependabot in #243
• build(deps): bump loader-utils and react-scripts in /examples/gif-fetcher by @dependabot in #242
• build(deps): bump jsdom and react-scripts in /examples/gif-fetcher by @dependabot in #241
• build(deps): bump tough-cookie and react-scripts in /examples/gif-fetcher by @dependabot in #240
• build(deps): bump shell-quote and react-scripts in /examples/gif-fetcher by @dependabot in #239
• chore: add P.map specific jsdoc for P.map by @momentiris in #245
• build(deps-dev): bump ejs from 3.1.9 to 3.1.10 in /examples/gif-fetcher by @dependabot in #249
• build(deps-dev): bump ejs from 3.1.9 to 3.1.10 by @dependabot in #248
• fix: exhaustive checking with nested P.nonNullable patterns by @gvergnaud in #252

New Contributors

• @momentiris made their first contribution in #245

Full Changelog: v5.1.1...v5.1.2

v5.1.1

What's Changed

• Fix(P.nonNullable): narrowing of unions of objects by @gvergnaud in #237

Full Changelog: v5.1.0...v5.1.1

v5.1.0

New features

P.nonNullable wildcard

Add a new P.nonNullable pattern that will match any value except null or undefined.

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

const input = null;

const output = match<number | null | undefined>(input)
  .with(P.nonNullable, () => 'it is a number!')
  .otherwise(() => 'it is either null or undefined!');

console.log(output);
// => 'it is either null or undefined!'

Closes #60 #154 #190 and will be a work-around for #143.

What's Changed

• feat: Add P.nonNullable patterns by @gvergnaud in #229

Full Changelog: v5.0.8...v5.1.0

v5.0.8

The main thing

This release includes type narrowing improvement to isMatching when used in its curried form:

type Pizza = { type: 'pizza', topping: string };
type Sandwich = { type: 'sandwich', condiments: string[] }
type Food =  Pizza | Sandwich;

declare const food: Food

const isPizza = isMatching({ type: 'pizza' })

if (isPizza(food)) {
  x  // Used to  infer `food` as `Food`, no infers `Pizza`
}

This also improves type checking performance for complex patterns and fixes a small bug in the ES5 build of TS-Pattern.

What's Changed

• perf: support exhaustive match on larger unions by @gvergnaud in #214
• fix: make isMatching(p) infer the pattern as a const type parameter by @gvergnaud in #221
• fix: Make sure regeneratorRuntime isn't included in the cjs build by @gvergnaud in #224

Full Changelog: v5.0.6...v5.0.8

v5.0.6

Close issue issues

• Exhaustive matching fix for read only arrays #206
• Fix incorrect JS docs #196

What's Changed

• Update README.md by @ndstephens in #161
• docs: add install instructions for bun and pnpm by @colinhacks in #186
• build(deps-dev): bump postcss from 8.4.23 to 8.4.31 by @dependabot in #199
• build(deps-dev): bump @babel/traverse from 7.21.5 to 7.23.2 by @dependabot in #200
• fix(readonly): exhaustive matching on readonly array by @gvergnaud in #207

New Contributors

• @ndstephens made their first contribution in #161
• @colinhacks made their first contribution in #186

Full Changelog: v5.0.5...v5.0.6