| 1 | /** |
| 2 | * Builds pattern matchers for TypeScript values. |
| 3 | * |
| 4 | * `Match` lets you add ordered cases and then finish them with a result, |
| 5 | * fallback, `Option`, or exhaustive check. Use `Match.type` to define a |
| 6 | * reusable matcher for a type, or `Match.value` to match one value immediately. |
| 7 | * Cases can match literal values, predicates, object shapes, tags, negated |
| 8 | * patterns, and common checks such as strings, numbers, records, and class |
| 9 | * instances. |
| 10 | * |
| 11 | * @since 4.0.0 |
| 12 | */ |
| 13 | import * as internal from "./internal/matcher.ts" |
| 14 | import type * as Option from "./Option.ts" |
| 15 | import type { Pipeable } from "./Pipeable.ts" |
| 16 | import * as Predicate from "./Predicate.ts" |
| 17 | import type * as Result from "./Result.ts" |
| 18 | import type * as T from "./Types.ts" |
| 19 | import type { Unify } from "./Unify.ts" |
| 20 | |
| 21 | const TypeId = internal.TypeId |
| 22 | |
| 23 | // The conditional must stay deferred until P is inferred. Replacing it with an |
| 24 | // intersection loses contextual typing for nested generic calls (microsoft/TypeScript#52864). |
| 25 | type Contextual<P, Fallback> = [P] extends [never] ? Fallback : P |
| 26 | |
| 27 | type TagHandlers<D extends string, R, Ret> = { |
| 28 | readonly [Tag in Types.Tags<D, R> & string]: (_: Extract<R, Record<D, Tag>>) => Ret |
| 29 | } |
| 30 | |
| 31 | type PartialTagHandlers<D extends string, R, Ret> = { |
| 32 | readonly [Tag in Types.Tags<D, R> & string]?: ((_: Extract<R, Record<D, Tag>>) => Ret) | undefined |
| 33 | } |
| 34 | |
| 35 | type ValueTagHandlers<I> = { |
| 36 | readonly [Tag in Types.Tags<"_tag", I> & string]: (_: Extract<I, { readonly _tag: Tag }>) => any |
| 37 | } |
| 38 | |
| 39 | /** |
| 40 | * Marker used by `Matcher` to distinguish matchers created with `Match.value`. |
| 41 | * |
| 42 | * @category models |
| 43 | * @since 4.0.0 |
| 44 | */ |
| 45 | export type ValueFlavor = "value" |
| 46 | |
| 47 | /** |
| 48 | * Union type for matchers created by `Match.type` and `Match.value`. |
| 49 | * |
| 50 | * **Details** |
| 51 | * |
| 52 | * A `Matcher` carries the input type, accumulated filters, remaining cases, |
| 53 | * result type, and a flavor distinguishing the two matcher variants: `never` |
| 54 | * for matchers created with `Match.type` and `ValueFlavor` for matchers created |
| 55 | * with `Match.value`. Because the flavor never depends on the input type, |
| 56 | * terminal combinators resolve even when the input contains type parameters. |
| 57 | * |
| 58 | * **Example** (Matching string and number values) |
| 59 | * |
| 60 | * ```ts import.meta.vitest |
| 61 | * import { Match } from "effect" |
| 62 | * |
| 63 | * // Simulated dynamic input that can be a string or a number |
| 64 | * const input: string | number = "some input" |
| 65 | * |
| 66 | * // ┌─── string |
| 67 | * // ▼ |
| 68 | * const result = Match.value(input).pipe( |
| 69 | * // Match if the value is a number |
| 70 | * Match.when(Match.number, (n) => `number: ${n}`), |
| 71 | * // Match if the value is a string |
| 72 | * Match.when(Match.string, (s) => `string: ${s}`), |
| 73 | * // Ensure all possible cases are covered |
| 74 | * Match.exhaustive |
| 75 | * ) |
| 76 | * |
| 77 | * result // => "string: some input" |
| 78 | * ``` |
| 79 | * |
| 80 | * @category models |
| 81 | * @since 4.0.0 |
| 82 | */ |
| 83 | export type Matcher< |
| 84 | Input, |
| 85 | Filters, |
| 86 | RemainingApplied, |
| 87 | Result, |
| 88 | Flavor, |
| 89 | Return = any, |
| 90 | Args extends Array<any> = [] |
| 91 | > = |
| 92 | | TypeMatcher<Input, Filters, RemainingApplied, Result, Return, Args> |
| 93 | | ValueMatcher<Input, Filters, RemainingApplied, Result, Input, Return, Flavor> |
| 94 | |
| 95 | /** |
| 96 | * Represents a pattern matcher that operates on types rather than specific values. |
| 97 | * |
| 98 | * **Details** |
| 99 | * |
| 100 | * A `TypeMatcher` is created when using `Match.type<T>()` and allows you to define |
| 101 | * patterns that will be applied to values of the specified type. It maintains |
| 102 | * type-level information about the input type, applied filters, remaining cases, |
| 103 | * and expected results. |
| 104 | * |
| 105 | * **Example** (Creating a type matcher) |
| 106 | * |
| 107 | * ```ts import.meta.vitest |
| 108 | * import { Match } from "effect" |
| 109 | * |
| 110 | * // Create a TypeMatcher for string | number |
| 111 | * const matcher = Match.type<string | number>().pipe( |
| 112 | * Match.when(Match.string, (s) => `String: ${s}`), |
| 113 | * Match.when(Match.number, (n) => `Number: ${n}`), |
| 114 | * Match.exhaustive |
| 115 | * ) |
| 116 | * |
| 117 | * matcher("hello") // => "String: hello" |
| 118 | * matcher(42) // => "Number: 42" |
| 119 | * ``` |
| 120 | * |
| 121 | * @category models |
| 122 | * @since 4.0.0 |
| 123 | */ |
| 124 | export interface TypeMatcher< |
| 125 | in Input, |
| 126 | out Filters, |
| 127 | out Remaining, |
| 128 | out Result, |
| 129 | out Return = any, |
| 130 | in Args extends Array<any> = [] |
| 131 | > extends Pipeable { |
| 132 | readonly _tag: "TypeMatcher" |
| 133 | readonly [TypeId]: { |
| 134 | readonly _input: T.Contravariant<Input> |
| 135 | readonly _filters: T.Covariant<Filters> |
| 136 | readonly _remaining: T.Covariant<Remaining> |
| 137 | readonly _result: T.Covariant<Result> |
| 138 | readonly _return: T.Covariant<Return> |
| 139 | readonly _args: T.Contravariant<Args> |
| 140 | } |
| 141 | readonly cases: ReadonlyArray<Case> |
| 142 | readonly select: (...args: Array<any>) => unknown |
| 143 | add<I, R, RA, A>(_case: Case): TypeMatcher<I, R, RA, A, Return, Args> |
| 144 | } |
| 145 | |
| 146 | /** |
| 147 | * Represents a pattern matcher that operates on a specific provided value. |
| 148 | * |
| 149 | * **Details** |
| 150 | * |
| 151 | * A `ValueMatcher` is created when using `Match.value(someValue)` and contains |
| 152 | * the actual value to be matched against. It tracks both the provided value |
| 153 | * and the result of applying patterns to determine matches. Its optional |
| 154 | * seventh type parameter is the matcher flavor and defaults to `ValueFlavor`. |
| 155 | * |
| 156 | * **Example** (Creating a value matcher) |
| 157 | * |
| 158 | * ```ts import.meta.vitest |
| 159 | * import { Match } from "effect" |
| 160 | * |
| 161 | * const input = { type: "user", name: "Alice", age: 30 } |
| 162 | * |
| 163 | * // Create a ValueMatcher for the specific input |
| 164 | * const result = Match.value(input).pipe( |
| 165 | * Match.when({ type: "user" }, (user) => `User: ${user.name}`), |
| 166 | * Match.when({ type: "admin" }, (admin) => `Admin: ${admin.name}`), |
| 167 | * Match.orElse(() => "Unknown type") |
| 168 | * ) |
| 169 | * |
| 170 | * result // => "User: Alice" |
| 171 | * ``` |
| 172 | * |
| 173 | * @category models |
| 174 | * @since 4.0.0 |
| 175 | */ |
| 176 | export interface ValueMatcher< |
| 177 | in Input, |
| 178 | Filters, |
| 179 | out Remaining, |
| 180 | out Result, |
| 181 | Provided, |
| 182 | out Return = any, |
| 183 | out Flavor = ValueFlavor |
| 184 | > extends Pipeable { |
| 185 | readonly _tag: "ValueMatcher" |
| 186 | readonly [TypeId]: { |
| 187 | readonly _input: T.Contravariant<Input> |
| 188 | readonly _filters: T.Covariant<Filters> |
| 189 | readonly _result: T.Covariant<Result> |
| 190 | readonly _return: T.Covariant<Return> |
| 191 | readonly _flavor: T.Covariant<Flavor> |
| 192 | } |
| 193 | readonly provided: Provided |
| 194 | readonly value: Result.Result<Provided, Remaining> |
| 195 | add<I, R, RA, A, Provided>(_case: Case): ValueMatcher<I, R, RA, A, Provided> |
| 196 | } |
| 197 | |
| 198 | /** |
| 199 | * Represents a single pattern matching case. |
| 200 | * |
| 201 | * **When to use** |
| 202 | * |
| 203 | * Use as the common public type for code that needs to inspect, store, or pass |
| 204 | * either positive or negative pattern matching cases. |
| 205 | * |
| 206 | * **Details** |
| 207 | * |
| 208 | * A `Case` can be either a positive match (`When`) or a negative match (`Not`). |
| 209 | * Cases are the building blocks of pattern matching logic and determine |
| 210 | * how values are tested and transformed. |
| 211 | * |
| 212 | * @see {@link When} for positive cases |
| 213 | * @see {@link Not} for negative cases |
| 214 | * |
| 215 | * @category models |
| 216 | * @since 4.0.0 |
| 217 | */ |
| 218 | export type Case = When | Not |
| 219 | |
| 220 | /** |
| 221 | * Represents a positive pattern matching case. |
| 222 | * |
| 223 | * **Details** |
| 224 | * |
| 225 | * A `When` case contains the logic to test if a value matches a specific pattern |
| 226 | * and the function to evaluate when the pattern matches. It's the primary |
| 227 | * building block for pattern matching conditions. |
| 228 | * |
| 229 | * **Example** (Creating positive match cases) |
| 230 | * |
| 231 | * ```ts import.meta.vitest |
| 232 | * import { Match } from "effect" |
| 233 | * |
| 234 | * // When creates cases that match specific patterns |
| 235 | * const stringMatcher = Match.type<string | number>().pipe( |
| 236 | * Match.when(Match.string, (s: string) => `Got string: ${s}`), |
| 237 | * Match.when(Match.number, (n: number) => `Got number: ${n}`), |
| 238 | * Match.exhaustive |
| 239 | * ) |
| 240 | * |
| 241 | * stringMatcher("hello") // => "Got string: hello" |
| 242 | * stringMatcher(42) // => "Got number: 42" |
| 243 | * ``` |
| 244 | * |
| 245 | * @category models |
| 246 | * @since 4.0.0 |
| 247 | */ |
| 248 | export interface When { |
| 249 | readonly _tag: "When" |
| 250 | guard(u: unknown): boolean |
| 251 | evaluate(input: unknown, ...args: Array<any>): any |
| 252 | } |
| 253 | |
| 254 | /** |
| 255 | * Represents a negative pattern matching case. |
| 256 | * |
| 257 | * **Details** |
| 258 | * |
| 259 | * A `Not` case contains the logic to test if a value does NOT match a specific |
| 260 | * pattern and the function to evaluate when the pattern doesn't match. It's used |
| 261 | * for exclusion-based pattern matching. |
| 262 | * |
| 263 | * **Example** (Creating negative match cases) |
| 264 | * |
| 265 | * ```ts import.meta.vitest |
| 266 | * import { Match } from "effect" |
| 267 | * |
| 268 | * // Not creates cases that exclude specific patterns |
| 269 | * const matcher = Match.type<string>().pipe( |
| 270 | * // Match any string except "forbidden" |
| 271 | * Match.not("forbidden", (s) => `Allowed: ${s}`), |
| 272 | * Match.orElse(() => "This string is forbidden") |
| 273 | * ) |
| 274 | * |
| 275 | * matcher("hello") // => "Allowed: hello" |
| 276 | * matcher("forbidden") // => "This string is forbidden" |
| 277 | * ``` |
| 278 | * |
| 279 | * @category models |
| 280 | * @since 4.0.0 |
| 281 | */ |
| 282 | export interface Not { |
| 283 | readonly _tag: "Not" |
| 284 | guard(u: unknown): boolean |
| 285 | evaluate(input: unknown, ...args: Array<any>): any |
| 286 | } |
| 287 | |
| 288 | /** |
| 289 | * Creates a matcher for a specific type. |
| 290 | * |
| 291 | * **When to use** |
| 292 | * |
| 293 | * Use to build a reusable matcher function for values of a known input type. |
| 294 | * |
| 295 | * **Details** |
| 296 | * |
| 297 | * This function defines a `Matcher` that operates on a given type, allowing you |
| 298 | * to specify conditions for handling different cases. Once the matcher is |
| 299 | * created, you can use pattern-matching functions like {@link when} to define |
| 300 | * how different values should be processed. |
| 301 | * |
| 302 | * **Example** (Matching Numbers and Strings) |
| 303 | * |
| 304 | * ```ts import.meta.vitest |
| 305 | * import { Match } from "effect" |
| 306 | * |
| 307 | * // Create a matcher for values that are either strings or numbers |
| 308 | * // |
| 309 | * // ┌─── (u: string | number) => string |
| 310 | * // ▼ |
| 311 | * const match = Match.type<string | number>().pipe( |
| 312 | * // Match when the value is a number |
| 313 | * Match.when(Match.number, (n) => `number: ${n}`), |
| 314 | * // Match when the value is a string |
| 315 | * Match.when(Match.string, (s) => `string: ${s}`), |
| 316 | * // Ensure all possible cases are handled |
| 317 | * Match.exhaustive |
| 318 | * ) |
| 319 | * |
| 320 | * match(0) // => "number: 0" |
| 321 | * |
| 322 | * match("hello") // => "string: hello" |
| 323 | * ``` |
| 324 | * |
| 325 | * @see {@link value} for creating a matcher from a specific value. |
| 326 | * |
| 327 | * @category constructors |
| 328 | * @since 4.0.0 |
| 329 | */ |
| 330 | export const type: <I>() => Matcher<I, Types.Without<never>, I, never, never> = internal.type |
| 331 | |
| 332 | /** |
| 333 | * Creates a reusable matcher from a function that selects the value to match. |
| 334 | * |
| 335 | * **Details** |
| 336 | * |
| 337 | * The compiled matcher keeps the selector's original argument list. Case |
| 338 | * handlers receive the narrowed selected value followed by those arguments. |
| 339 | * |
| 340 | * **Example** (Creating a reusable matcher) |
| 341 | * |
| 342 | * ```ts import.meta.vitest |
| 343 | * import { Match } from "effect" |
| 344 | * |
| 345 | * const format = Match.fn((prefix: string, value: "a" | "b") => value).pipe( |
| 346 | * Match.when("a", (_value, prefix) => `${prefix}: A`), |
| 347 | * Match.when("b", (_value, prefix) => `${prefix}: B`), |
| 348 | * Match.exhaustive |
| 349 | * ) |
| 350 | * |
| 351 | * format("status", "a") // => "status: A" |
| 352 | * ``` |
| 353 | * |
| 354 | * @category constructors |
| 355 | * @since 4.0.0 |
| 356 | */ |
| 357 | export const fn: <Args extends Array<any>, I>( |
| 358 | select: (...args: Args) => I |
| 359 | ) => Matcher<I, Types.Without<never>, I, never, never, any, Args> = internal.fn |
| 360 | |
| 361 | /** |
| 362 | * Creates a matcher from a specific value. |
| 363 | * |
| 364 | * **When to use** |
| 365 | * |
| 366 | * Use to match one concrete input immediately. |
| 367 | * |
| 368 | * **Details** |
| 369 | * |
| 370 | * This function allows you to define a `Matcher` directly from a given value, |
| 371 | * rather than from a type. This is useful when working with known values, |
| 372 | * enabling structured pattern matching on objects, primitives, or any data |
| 373 | * structure. |
| 374 | * |
| 375 | * Once the matcher is created, you can use pattern-matching functions like |
| 376 | * {@link when} to define how different cases should be handled. |
| 377 | * |
| 378 | * **Example** (Matching an Object by Property) |
| 379 | * |
| 380 | * ```ts import.meta.vitest |
| 381 | * import { Match } from "effect" |
| 382 | * |
| 383 | * const input = { name: "John", age: 30 } |
| 384 | * |
| 385 | * // Create a matcher for the specific object |
| 386 | * const result = Match.value(input).pipe( |
| 387 | * // Match when the 'name' property is "John" |
| 388 | * Match.when( |
| 389 | * { name: "John" }, |
| 390 | * (user) => `${user.name} is ${user.age} years old` |
| 391 | * ), |
| 392 | * // Provide a fallback if no match is found |
| 393 | * Match.orElse(() => "Oh, not John") |
| 394 | * ) |
| 395 | * |
| 396 | * result // => "John is 30 years old" |
| 397 | * ``` |
| 398 | * |
| 399 | * @see {@link type} for creating a matcher from a specific type. |
| 400 | * |
| 401 | * @category constructors |
| 402 | * @since 4.0.0 |
| 403 | */ |
| 404 | export const value: <const I>( |
| 405 | i: I |
| 406 | ) => Matcher<I, Types.Without<never>, I, never, ValueFlavor> = internal.value |
| 407 | |
| 408 | /** |
| 409 | * Creates a match function for a specific value with discriminated union handling. |
| 410 | * |
| 411 | * **Details** |
| 412 | * |
| 413 | * This function provides a convenient way to pattern match on discriminated unions |
| 414 | * by providing an object that maps each `_tag` value to its corresponding handler. |
| 415 | * It's similar to a switch statement but with better type safety and exhaustiveness checking. |
| 416 | * |
| 417 | * **Example** (Matching value tags) |
| 418 | * |
| 419 | * ```ts import.meta.vitest |
| 420 | * import { Match } from "effect" |
| 421 | * |
| 422 | * type Status = { readonly _tag: "Success"; readonly data: string } |
| 423 | * |
| 424 | * const success: Status = { _tag: "Success", data: "Hello" } |
| 425 | * |
| 426 | * // Simple valueTags usage |
| 427 | * const message = Match.valueTags(success, { |
| 428 | * Success: (result) => `Success: ${result.data}` |
| 429 | * }) |
| 430 | * |
| 431 | * message // => "Success: Hello" |
| 432 | * ``` |
| 433 | * |
| 434 | * @category constructors |
| 435 | * @since 4.0.0 |
| 436 | */ |
| 437 | export const valueTags: { |
| 438 | < |
| 439 | const I, |
| 440 | P extends |
| 441 | & ValueTagHandlers<I> |
| 442 | & { readonly [Tag in Exclude<keyof P, Types.Tags<"_tag", I>>]: never } |
| 443 | >( |
| 444 | fields: Contextual<P, ValueTagHandlers<I>> |
| 445 | ): (input: I) => Unify<ReturnType<P[keyof P]>> |
| 446 | < |
| 447 | const I, |
| 448 | P extends |
| 449 | & ValueTagHandlers<I> |
| 450 | & { readonly [Tag in Exclude<keyof P, Types.Tags<"_tag", I>>]: never } |
| 451 | >( |
| 452 | input: I, |
| 453 | fields: Contextual<P, ValueTagHandlers<I>> |
| 454 | ): Unify<ReturnType<P[keyof P]>> |
| 455 | } = internal.valueTags |
| 456 | |
| 457 | /** |
| 458 | * Creates a type-safe match function for discriminated unions based on `_tag` field. |
| 459 | * |
| 460 | * **Details** |
| 461 | * |
| 462 | * This function allows you to define exhaustive pattern matching for discriminated unions |
| 463 | * by providing handlers for each possible `_tag` value. It ensures type safety and |
| 464 | * can optionally enforce a specific return type across all branches. |
| 465 | * |
| 466 | * **Example** (Matching type tags) |
| 467 | * |
| 468 | * ```ts import.meta.vitest |
| 469 | * import { Match } from "effect" |
| 470 | * |
| 471 | * type Result = |
| 472 | * | { readonly _tag: "Success"; readonly data: string } |
| 473 | * | { readonly _tag: "Error"; readonly message: string } |
| 474 | * | { readonly _tag: "Loading" } |
| 475 | * |
| 476 | * // Create a matcher with specific return type |
| 477 | * const formatResult = Match.typeTags<Result, string>()({ |
| 478 | * Success: (result) => `Data: ${result.data}`, |
| 479 | * Error: (result) => `Error: ${result.message}`, |
| 480 | * Loading: () => "Loading..." |
| 481 | * }) |
| 482 | * |
| 483 | * formatResult({ _tag: "Success", data: "Hello World" }) // => "Data: Hello World" |
| 484 | * |
| 485 | * formatResult({ _tag: "Error", message: "Network failed" }) // => "Error: Network failed" |
| 486 | * |
| 487 | * // Create a matcher with inferred return type |
| 488 | * const processResult = Match.typeTags<Result>()({ |
| 489 | * Success: (result) => ({ type: "ok", value: result.data }), |
| 490 | * Error: (result) => ({ type: "error", error: result.message }), |
| 491 | * Loading: () => ({ type: "pending" }) |
| 492 | * }) |
| 493 | * |
| 494 | * processResult({ _tag: "Loading" }) // => { type: "pending" } |
| 495 | * ``` |
| 496 | * |
| 497 | * @category constructors |
| 498 | * @since 4.0.0 |
| 499 | */ |
| 500 | export const typeTags: { |
| 501 | <I, Ret>(): < |
| 502 | P extends |
| 503 | & { |
| 504 | readonly [Tag in Types.Tags<"_tag", I> & string]: ( |
| 505 | _: Extract<I, { readonly _tag: Tag }> |
| 506 | ) => Ret |
| 507 | } |
| 508 | & { readonly [Tag in Exclude<keyof P, Types.Tags<"_tag", I>>]: never } |
| 509 | >(fields: P) => (input: I) => Ret |
| 510 | <I>(): < |
| 511 | P extends |
| 512 | & { |
| 513 | readonly [Tag in Types.Tags<"_tag", I> & string]: ( |
| 514 | _: Extract<I, { readonly _tag: Tag }> |
| 515 | ) => any |
| 516 | } |
| 517 | & { readonly [Tag in Exclude<keyof P, Types.Tags<"_tag", I>>]: never } |
| 518 | >(fields: P) => (input: I) => Unify<ReturnType<P[keyof P]>> |
| 519 | } = internal.typeTags |
| 520 | |
| 521 | /** |
| 522 | * Ensures that all branches of a matcher return a specific type. |
| 523 | * |
| 524 | * **Details** |
| 525 | * |
| 526 | * This function enforces a consistent return type across all pattern-matching |
| 527 | * branches. By specifying a return type, TypeScript will check that every |
| 528 | * matching condition produces a value of the expected type. |
| 529 | * |
| 530 | * **Important:** This function must be the first step in the matcher pipeline. |
| 531 | * If used later, TypeScript will not enforce type consistency correctly. |
| 532 | * |
| 533 | * **Example** (Validating return type consistency) |
| 534 | * |
| 535 | * ```ts import.meta.vitest |
| 536 | * import { Match } from "effect" |
| 537 | * |
| 538 | * const match = Match.type<{ a: number } | { b: string }>().pipe( |
| 539 | * // Ensure all branches return a string |
| 540 | * Match.withReturnType<string>(), |
| 541 | * // ❌ Type error: 'number' is not assignable to type 'string' |
| 542 | * // @ts-expect-error |
| 543 | * Match.when({ a: Match.number }, (_) => _.a), |
| 544 | * // ✅ Correct: returns a string |
| 545 | * Match.when({ b: Match.string }, (_) => _.b), |
| 546 | * Match.exhaustive |
| 547 | * ) |
| 548 | * ``` |
| 549 | * |
| 550 | * @category utility types |
| 551 | * @since 4.0.0 |
| 552 | */ |
| 553 | export const withReturnType: <Ret>() => <I, F, R, A, Pr, _, Args extends Array<any>>( |
| 554 | self: Matcher<I, F, R, A, Pr, _, Args> |
| 555 | ) => [Ret] extends [[A] extends [never] ? any : A] ? Matcher<I, F, R, A, Pr, Ret, Args> |
| 556 | : "withReturnType constraint does not extend Result type" = internal.withReturnType |
| 557 | |
| 558 | /** |
| 559 | * Defines a condition for matching values. |
| 560 | * |
| 561 | * **When to use** |
| 562 | * |
| 563 | * Use to add one positive pattern case to a `Match.type` or `Match.value` |
| 564 | * pipeline when a direct value, predicate, or structured object pattern should |
| 565 | * run a handler for matching input. |
| 566 | * |
| 567 | * **Details** |
| 568 | * |
| 569 | * Supports both direct value comparisons and predicate functions. If the |
| 570 | * pattern matches, the associated function is executed and the matched input is |
| 571 | * removed from the remaining cases tracked by the matcher. |
| 572 | * |
| 573 | * **Example** (Matching with values and predicates) |
| 574 | * |
| 575 | * ```ts import.meta.vitest |
| 576 | * import { Match } from "effect" |
| 577 | * |
| 578 | * // Create a matcher for objects with an "age" property |
| 579 | * const match = Match.type<{ age: number }>().pipe( |
| 580 | * // Match when age is greater than 18 |
| 581 | * Match.when( |
| 582 | * { age: (age: number) => age > 18 }, |
| 583 | * (user: { age: number }) => `Age: ${user.age}` |
| 584 | * ), |
| 585 | * // Match when age is exactly 18 |
| 586 | * Match.when({ age: 18 }, () => "You can vote"), |
| 587 | * // Fallback case for all other ages |
| 588 | * Match.orElse((user: { age: number }) => `${user.age} is too young`) |
| 589 | * ) |
| 590 | * |
| 591 | * match({ age: 20 }) // => "Age: 20" |
| 592 | * |
| 593 | * match({ age: 18 }) // => "You can vote" |
| 594 | * |
| 595 | * match({ age: 4 }) // => "4 is too young" |
| 596 | * ``` |
| 597 | * |
| 598 | * @see {@link whenOr} for handling any one of several patterns with the same handler |
| 599 | * @see {@link whenAnd} for requiring all provided patterns to match before running a handler |
| 600 | * @see {@link not} for handling inputs that do not match a pattern |
| 601 | * @see {@link orElse} for providing a fallback when no pattern case matches |
| 602 | * |
| 603 | * @category defining patterns |
| 604 | * @since 4.0.0 |
| 605 | */ |
| 606 | export const when: < |
| 607 | R, |
| 608 | const P extends Types.PatternPrimitive<R> | Types.PatternBase<R>, |
| 609 | Ret, |
| 610 | Args extends Array<any>, |
| 611 | Fn extends (_: Types.WhenMatch<R, P>, ...args: Args) => Ret |
| 612 | >( |
| 613 | pattern: P, |
| 614 | f: Fn |
| 615 | ) => <I, F, A, Pr>( |
| 616 | self: Matcher<I, F, R, A, Pr, Ret, Args> |
| 617 | ) => Matcher< |
| 618 | I, |
| 619 | Types.AddWithout<F, Types.PForExclude<P>>, |
| 620 | Types.ApplyFilters<I, Types.AddWithout<F, Types.PForExclude<P>>>, |
| 621 | A | ReturnType<Fn>, |
| 622 | Pr, |
| 623 | Ret, |
| 624 | Args |
| 625 | > = internal.when |
| 626 | |
| 627 | /** |
| 628 | * Matches one of multiple patterns in a single condition. |
| 629 | * |
| 630 | * **Details** |
| 631 | * |
| 632 | * This function allows defining a condition where a value matches any of the |
| 633 | * provided patterns. If a match is found, the associated function is executed. |
| 634 | * It simplifies cases where multiple patterns share the same handling logic. |
| 635 | * |
| 636 | * Unlike {@link when}, which requires separate conditions for each pattern, |
| 637 | * this function enables combining them into a single statement, making the |
| 638 | * matcher more concise. |
| 639 | * |
| 640 | * **Example** (Matching one of several patterns) |
| 641 | * |
| 642 | * ```ts import.meta.vitest |
| 643 | * import { Match } from "effect" |
| 644 | * |
| 645 | * type ErrorType = |
| 646 | * | { readonly _tag: "NetworkError"; readonly message: string } |
| 647 | * | { readonly _tag: "TimeoutError"; readonly duration: number } |
| 648 | * | { readonly _tag: "ValidationError"; readonly field: string } |
| 649 | * |
| 650 | * const handleError = Match.type<ErrorType>().pipe( |
| 651 | * Match.whenOr( |
| 652 | * { _tag: "NetworkError" }, |
| 653 | * { _tag: "TimeoutError" }, |
| 654 | * () => "Retry the request" |
| 655 | * ), |
| 656 | * Match.when({ _tag: "ValidationError" }, (_) => `Invalid field: ${_.field}`), |
| 657 | * Match.exhaustive |
| 658 | * ) |
| 659 | * |
| 660 | * handleError({ _tag: "NetworkError", message: "No connection" }) // => "Retry the request" |
| 661 | * |
| 662 | * handleError({ _tag: "ValidationError", field: "email" }) // => "Invalid field: email" |
| 663 | * ``` |
| 664 | * |
| 665 | * @category defining patterns |
| 666 | * @since 4.0.0 |
| 667 | */ |
| 668 | export const whenOr: < |
| 669 | R, |
| 670 | const P extends ReadonlyArray<Types.PatternPrimitive<R> | Types.PatternBase<R>>, |
| 671 | Ret, |
| 672 | Args extends Array<any>, |
| 673 | Fn extends (_: Types.WhenMatch<R, P[number]>, ...args: Args) => Ret |
| 674 | >( |
| 675 | ...args: [...patterns: P, f: Fn] |
| 676 | ) => <I, F, A, Pr>( |
| 677 | self: Matcher<I, F, R, A, Pr, Ret, Args> |
| 678 | ) => Matcher< |
| 679 | I, |
| 680 | Types.AddWithout<F, Types.PForExclude<P[number]>>, |
| 681 | Types.ApplyFilters<I, Types.AddWithout<F, Types.PForExclude<P[number]>>>, |
| 682 | A | ReturnType<Fn>, |
| 683 | Pr, |
| 684 | Ret, |
| 685 | Args |
| 686 | > = internal.whenOr |
| 687 | |
| 688 | /** |
| 689 | * Matches a value that satisfies all provided patterns. |
| 690 | * |
| 691 | * **Details** |
| 692 | * |
| 693 | * This function allows defining a condition where a value must match all the |
| 694 | * given patterns simultaneously. If the value satisfies every pattern, the |
| 695 | * associated function is executed. |
| 696 | * |
| 697 | * Unlike {@link when}, which matches a single pattern at a time, this function |
| 698 | * ensures that multiple conditions are met before executing the callback. It is |
| 699 | * useful when checking for values that need to fulfill multiple criteria at |
| 700 | * once. |
| 701 | * |
| 702 | * **Example** (Matching all provided patterns) |
| 703 | * |
| 704 | * ```ts import.meta.vitest |
| 705 | * import { Match } from "effect" |
| 706 | * |
| 707 | * type User = { readonly age: number; readonly role: "admin" | "user" } |
| 708 | * |
| 709 | * const checkUser = Match.type<User>().pipe( |
| 710 | * Match.whenAnd( |
| 711 | * { age: (n) => n >= 18 }, |
| 712 | * { role: "admin" }, |
| 713 | * () => "Admin access granted" |
| 714 | * ), |
| 715 | * Match.orElse(() => "Access denied") |
| 716 | * ) |
| 717 | * |
| 718 | * checkUser({ age: 20, role: "admin" }) // => "Admin access granted" |
| 719 | * |
| 720 | * checkUser({ age: 20, role: "user" }) // => "Access denied" |
| 721 | * ``` |
| 722 | * |
| 723 | * @category defining patterns |
| 724 | * @since 4.0.0 |
| 725 | */ |
| 726 | export const whenAnd: < |
| 727 | R, |
| 728 | const P extends ReadonlyArray<Types.PatternPrimitive<R> | Types.PatternBase<R>>, |
| 729 | Ret, |
| 730 | Args extends Array<any>, |
| 731 | Fn extends (_: Types.WhenMatch<R, T.UnionToIntersection<P[number]>>, ...args: Args) => Ret |
| 732 | >( |
| 733 | ...args: [...patterns: P, f: Fn] |
| 734 | ) => <I, F, A, Pr>( |
| 735 | self: Matcher<I, F, R, A, Pr, Ret, Args> |
| 736 | ) => Matcher< |
| 737 | I, |
| 738 | Types.AddWithout<F, Types.PForExclude<T.UnionToIntersection<P[number]>>>, |
| 739 | Types.ApplyFilters<I, Types.AddWithout<F, Types.PForExclude<T.UnionToIntersection<P[number]>>>>, |
| 740 | A | ReturnType<Fn>, |
| 741 | Pr, |
| 742 | Ret, |
| 743 | Args |
| 744 | > = internal.whenAnd |
| 745 | |
| 746 | /** |
| 747 | * Matches values based on a specified discriminant field. |
| 748 | * |
| 749 | * **When to use** |
| 750 | * |
| 751 | * Use to match one or more exact values of a discriminator field. |
| 752 | * |
| 753 | * **Details** |
| 754 | * |
| 755 | * This function is used to define pattern matching on objects that follow a |
| 756 | * **discriminated union** structure, where a specific field (e.g., `type`, |
| 757 | * `kind`, `_tag`) determines the variant of the object. It allows matching |
| 758 | * multiple values of the discriminant and provides a function to handle the |
| 759 | * matched cases. |
| 760 | * |
| 761 | * **Example** (Matching on a discriminator field) |
| 762 | * |
| 763 | * ```ts import.meta.vitest |
| 764 | * import { Match, pipe } from "effect" |
| 765 | * |
| 766 | * const match = pipe( |
| 767 | * Match.type< |
| 768 | * { type: "A"; a: string } | { type: "B"; b: number } | { |
| 769 | * type: "C" |
| 770 | * c: boolean |
| 771 | * } |
| 772 | * >(), |
| 773 | * Match.discriminator("type")("A", "B", (_) => `A or B: ${_.type}`), |
| 774 | * Match.discriminator("type")("C", (_) => `C(${_.c})`), |
| 775 | * Match.exhaustive |
| 776 | * ) |
| 777 | * match({ type: "A", a: "ok" }) // => "A or B: A" |
| 778 | * match({ type: "C", c: true }) // => "C(true)" |
| 779 | * ``` |
| 780 | * |
| 781 | * @see {@link discriminators} for defining several discriminator handlers at once |
| 782 | * @see {@link discriminatorStartsWith} for matching string discriminator values by prefix |
| 783 | * |
| 784 | * @category defining patterns |
| 785 | * @since 4.0.0 |
| 786 | */ |
| 787 | export const discriminator: <D extends string>( |
| 788 | field: D |
| 789 | ) => <R, P extends Types.Tags<D, R> & string, Ret, Fn extends (_: Extract<R, Record<D, P>>) => Ret>( |
| 790 | ...pattern: [first: P, ...values: Array<P>, f: Fn] |
| 791 | ) => <I, F, A, Pr>( |
| 792 | self: Matcher<I, F, R, A, Pr, Ret> |
| 793 | ) => Matcher< |
| 794 | I, |
| 795 | Types.AddWithout<F, Extract<R, Record<D, P>>>, |
| 796 | Types.ApplyFilters<I, Types.AddWithout<F, Extract<R, Record<D, P>>>>, |
| 797 | A | ReturnType<Fn>, |
| 798 | Pr, |
| 799 | Ret |
| 800 | > = internal.discriminator |
| 801 | |
| 802 | /** |
| 803 | * Matches values where a specified field starts with a given prefix. |
| 804 | * |
| 805 | * **When to use** |
| 806 | * |
| 807 | * Use to match string discriminator values by prefix instead of exact value. |
| 808 | * |
| 809 | * **Details** |
| 810 | * |
| 811 | * Instead of checking for exact matches, this helper matches values that share |
| 812 | * a common prefix. For example, if the discriminant field contains hierarchical |
| 813 | * names like `"A"`, `"A.A"`, and `"B"`, a single `"A"` rule can match both |
| 814 | * `"A"` and `"A.A"`. |
| 815 | * |
| 816 | * **Example** (Matching discriminator prefixes) |
| 817 | * |
| 818 | * ```ts import.meta.vitest |
| 819 | * import { Match, pipe } from "effect" |
| 820 | * |
| 821 | * const match = pipe( |
| 822 | * Match.type<{ type: "A" } | { type: "B" } | { type: "A.A" } | {}>(), |
| 823 | * Match.discriminatorStartsWith("type")("A", (_) => 1 as const), |
| 824 | * Match.discriminatorStartsWith("type")("B", (_) => 2 as const), |
| 825 | * Match.orElse((_) => 3 as const) |
| 826 | * ) |
| 827 | * |
| 828 | * match({ type: "A" }) // => 1 |
| 829 | * match({ type: "B" }) // => 2 |
| 830 | * match({ type: "A.A" }) // => 1 |
| 831 | * ``` |
| 832 | * |
| 833 | * @see {@link discriminator} for matching exact discriminator values |
| 834 | * |
| 835 | * @category defining patterns |
| 836 | * @since 4.0.0 |
| 837 | */ |
| 838 | export const discriminatorStartsWith: <D extends string>( |
| 839 | field: D |
| 840 | ) => <R, P extends string, Ret, Fn extends (_: Extract<R, Record<D, `${P}${string}`>>) => Ret>( |
| 841 | pattern: P, |
| 842 | f: Fn |
| 843 | ) => <I, F, A, Pr>( |
| 844 | self: Matcher<I, F, R, A, Pr, Ret> |
| 845 | ) => Matcher< |
| 846 | I, |
| 847 | Types.AddWithout<F, Extract<R, Record<D, `${P}${string}`>>>, |
| 848 | Types.ApplyFilters<I, Types.AddWithout<F, Extract<R, Record<D, `${P}${string}`>>>>, |
| 849 | A | ReturnType<Fn>, |
| 850 | Pr, |
| 851 | Ret |
| 852 | > = internal.discriminatorStartsWith |
| 853 | |
| 854 | /** |
| 855 | * Matches values based on a field that serves as a discriminator, mapping each |
| 856 | * possible value to a corresponding handler. |
| 857 | * |
| 858 | * **When to use** |
| 859 | * |
| 860 | * Use to define several discriminator handlers at once without finalizing the |
| 861 | * matcher. |
| 862 | * |
| 863 | * **Details** |
| 864 | * |
| 865 | * This function simplifies working with discriminated unions by letting you |
| 866 | * define a set of handlers for each possible value of a given field. Instead of |
| 867 | * chaining multiple calls to {@link discriminator}, this function allows |
| 868 | * defining all possible cases at once using an object where the keys are the |
| 869 | * possible values of the field, and the values are the corresponding handler |
| 870 | * functions. |
| 871 | * |
| 872 | * **Example** (Mapping discriminator handlers) |
| 873 | * |
| 874 | * ```ts import.meta.vitest |
| 875 | * import { Match, pipe } from "effect" |
| 876 | * |
| 877 | * const match = pipe( |
| 878 | * Match.type< |
| 879 | * { type: "A"; a: string } | { type: "B"; b: number } | { |
| 880 | * type: "C" |
| 881 | * c: boolean |
| 882 | * } |
| 883 | * >(), |
| 884 | * Match.discriminators("type")({ |
| 885 | * A: (a) => a.a, |
| 886 | * B: (b) => b.b, |
| 887 | * C: (c) => c.c |
| 888 | * }), |
| 889 | * Match.exhaustive |
| 890 | * ) |
| 891 | * match({ type: "A", a: "ok" }) // => "ok" |
| 892 | * match({ type: "B", b: 42 }) // => 42 |
| 893 | * ``` |
| 894 | * |
| 895 | * @see {@link discriminator} for adding one discriminator case to a matcher pipeline |
| 896 | * @see {@link discriminatorsExhaustive} for handling every discriminator value and finalizing the matcher |
| 897 | * |
| 898 | * @category defining patterns |
| 899 | * @since 4.0.0 |
| 900 | */ |
| 901 | export const discriminators: <D extends string>( |
| 902 | field: D |
| 903 | ) => < |
| 904 | R, |
| 905 | Ret, |
| 906 | P extends |
| 907 | & PartialTagHandlers<D, R, Ret> |
| 908 | & { readonly [Tag in Exclude<keyof P, Types.Tags<D, R>>]: never } |
| 909 | >( |
| 910 | fields: Contextual<P, PartialTagHandlers<D, R, Ret>> |
| 911 | ) => <I, F, A, Pr>( |
| 912 | self: Matcher<I, F, R, A, Pr, Ret> |
| 913 | ) => Matcher< |
| 914 | I, |
| 915 | Types.AddWithout<F, Extract<R, Record<D, keyof P>>>, |
| 916 | Types.ApplyFilters<I, Types.AddWithout<F, Extract<R, Record<D, keyof P>>>>, |
| 917 | A | ReturnType<P[keyof P] & {}>, |
| 918 | Pr, |
| 919 | Ret |
| 920 | > = internal.discriminators |
| 921 | |
| 922 | /** |
| 923 | * Matches values by a discriminator field and requires every possible case to |
| 924 | * be handled. |
| 925 | * |
| 926 | * **When to use** |
| 927 | * |
| 928 | * Use to define an exhaustive discriminator handler map that finalizes the |
| 929 | * matcher. |
| 930 | * |
| 931 | * **Details** |
| 932 | * |
| 933 | * This is the exhaustive variant of {@link discriminators}. Each possible |
| 934 | * discriminator value must have a corresponding handler, so the matcher is |
| 935 | * finalized directly and does not require `Match.exhaustive` at the end of the |
| 936 | * pipeline. |
| 937 | * |
| 938 | * **Example** (Handling all discriminator cases) |
| 939 | * |
| 940 | * ```ts import.meta.vitest |
| 941 | * import { Match, pipe } from "effect" |
| 942 | * |
| 943 | * const match = pipe( |
| 944 | * Match.type< |
| 945 | * { type: "A"; a: string } | { type: "B"; b: number } | { |
| 946 | * type: "C" |
| 947 | * c: boolean |
| 948 | * } |
| 949 | * >(), |
| 950 | * Match.discriminatorsExhaustive("type")({ |
| 951 | * A: (a) => a.a, |
| 952 | * B: (b) => b.b, |
| 953 | * C: (c) => c.c |
| 954 | * }) |
| 955 | * ) |
| 956 | * match({ type: "C", c: true }) // => true |
| 957 | * ``` |
| 958 | * |
| 959 | * @see {@link discriminators} for defining discriminator handlers without finalizing the matcher |
| 960 | * |
| 961 | * @category defining patterns |
| 962 | * @since 4.0.0 |
| 963 | */ |
| 964 | export const discriminatorsExhaustive: <D extends string>( |
| 965 | field: D |
| 966 | ) => < |
| 967 | R, |
| 968 | Ret, |
| 969 | P extends |
| 970 | & TagHandlers<D, R, Ret> |
| 971 | & { readonly [Tag in Exclude<keyof P, Types.Tags<D, R>>]: never } |
| 972 | >( |
| 973 | fields: Contextual<P, TagHandlers<D, R, Ret>> |
| 974 | ) => <I, F, A, Pr>( |
| 975 | self: Matcher<I, F, R, A, Pr, Ret> |
| 976 | ) => [Pr] extends [never] ? (u: I) => Unify<A | ReturnType<P[keyof P]>> : Unify<A | ReturnType<P[keyof P]>> = |
| 977 | internal.discriminatorsExhaustive |
| 978 | |
| 979 | /** |
| 980 | * Matches discriminated union members by their `_tag` field. |
| 981 | * |
| 982 | * **When to use** |
| 983 | * |
| 984 | * Use to handle one or more `_tag` cases with the same matcher branch. |
| 985 | * |
| 986 | * **Details** |
| 987 | * |
| 988 | * This helper follows the Effect convention that discriminated unions use |
| 989 | * `"_tag"` as their discriminator field. Use {@link discriminator} for a |
| 990 | * different discriminator field. |
| 991 | * |
| 992 | * **Example** (Matching a discriminated union by tag) |
| 993 | * |
| 994 | * ```ts import.meta.vitest |
| 995 | * import { Match } from "effect" |
| 996 | * |
| 997 | * type Event = |
| 998 | * | { readonly _tag: "fetch" } |
| 999 | * | { readonly _tag: "success"; readonly data: string } |
| 1000 | * | { readonly _tag: "error"; readonly error: Error } |
| 1001 | * | { readonly _tag: "cancel" } |
| 1002 | * |
| 1003 | * const match = Match.type<Event>().pipe( |
| 1004 | * // Match either "fetch" or "success" |
| 1005 | * Match.tag("fetch", "success", () => `Ok!`), |
| 1006 | * // Match "error" and extract the error message |
| 1007 | * Match.tag("error", (event) => `Error: ${event.error.message}`), |
| 1008 | * // Match "cancel" |
| 1009 | * Match.tag("cancel", () => "Cancelled"), |
| 1010 | * Match.exhaustive |
| 1011 | * ) |
| 1012 | * |
| 1013 | * match({ _tag: "success", data: "Hello" }) // => "Ok!" |
| 1014 | * |
| 1015 | * match({ _tag: "error", error: new Error("Oops!") }) // => "Error: Oops!" |
| 1016 | * ``` |
| 1017 | * |
| 1018 | * @category defining patterns |
| 1019 | * @since 4.0.0 |
| 1020 | */ |
| 1021 | export const tag: < |
| 1022 | R, |
| 1023 | P extends Types.Tags<"_tag", R> & string, |
| 1024 | Ret, |
| 1025 | Args extends Array<any>, |
| 1026 | Fn extends (_: Extract<R, Record<"_tag", P>>, ...args: Args) => Ret |
| 1027 | >( |
| 1028 | ...pattern: [first: P, ...values: Array<P>, f: Fn] |
| 1029 | ) => <I, F, A, Pr>( |
| 1030 | self: Matcher<I, F, R, A, Pr, Ret, Args> |
| 1031 | ) => Matcher< |
| 1032 | I, |
| 1033 | Types.AddWithout<F, Extract<R, Record<"_tag", P>>>, |
| 1034 | Types.ApplyFilters<I, Types.AddWithout<F, Extract<R, Record<"_tag", P>>>>, |
| 1035 | ReturnType<Fn> | A, |
| 1036 | Pr, |
| 1037 | Ret, |
| 1038 | Args |
| 1039 | > = internal.tag |
| 1040 | |
| 1041 | /** |
| 1042 | * Matches values where the `_tag` field starts with a given prefix. |
| 1043 | * |
| 1044 | * **Details** |
| 1045 | * |
| 1046 | * This function allows you to match on values in a **discriminated union** |
| 1047 | * based on whether the `_tag` field starts with a specified prefix. It is |
| 1048 | * useful for handling hierarchical or namespaced tags, where multiple related |
| 1049 | * cases share a common prefix. |
| 1050 | * |
| 1051 | * **Example** (Matching tag prefixes) |
| 1052 | * |
| 1053 | * ```ts import.meta.vitest |
| 1054 | * import { Match, pipe } from "effect" |
| 1055 | * |
| 1056 | * const match = pipe( |
| 1057 | * Match.type<{ _tag: "A" } | { _tag: "B" } | { _tag: "A.A" } | {}>(), |
| 1058 | * Match.tagStartsWith("A", (_) => 1 as const), |
| 1059 | * Match.tagStartsWith("B", (_) => 2 as const), |
| 1060 | * Match.orElse((_) => 3 as const) |
| 1061 | * ) |
| 1062 | * |
| 1063 | * match({ _tag: "A" }) // => 1 |
| 1064 | * match({ _tag: "B" }) // => 2 |
| 1065 | * match({ _tag: "A.A" }) // => 1 |
| 1066 | * ``` |
| 1067 | * |
| 1068 | * @category defining patterns |
| 1069 | * @since 4.0.0 |
| 1070 | */ |
| 1071 | export const tagStartsWith: < |
| 1072 | R, |
| 1073 | P extends string, |
| 1074 | Ret, |
| 1075 | Fn extends (_: Extract<R, Record<"_tag", `${P}${string}`>>) => Ret |
| 1076 | >( |
| 1077 | pattern: P, |
| 1078 | f: Fn |
| 1079 | ) => <I, F, A, Pr>( |
| 1080 | self: Matcher<I, F, R, A, Pr, Ret> |
| 1081 | ) => Matcher< |
| 1082 | I, |
| 1083 | Types.AddWithout<F, Extract<R, Record<"_tag", `${P}${string}`>>>, |
| 1084 | Types.ApplyFilters<I, Types.AddWithout<F, Extract<R, Record<"_tag", `${P}${string}`>>>>, |
| 1085 | ReturnType<Fn> | A, |
| 1086 | Pr, |
| 1087 | Ret |
| 1088 | > = internal.tagStartsWith |
| 1089 | |
| 1090 | /** |
| 1091 | * Matches values based on their `_tag` field, mapping each tag to a |
| 1092 | * corresponding handler. |
| 1093 | * |
| 1094 | * **Details** |
| 1095 | * |
| 1096 | * This function provides a way to handle discriminated unions by mapping `_tag` |
| 1097 | * values to specific functions. Each handler receives the matched value and |
| 1098 | * returns a transformed result. If all possible tags are handled, you can |
| 1099 | * enforce exhaustiveness using `Match.exhaustive` to ensure no case is missed. |
| 1100 | * |
| 1101 | * **Example** (Mapping tag handlers) |
| 1102 | * |
| 1103 | * ```ts import.meta.vitest |
| 1104 | * import { Match, pipe } from "effect" |
| 1105 | * |
| 1106 | * const match = pipe( |
| 1107 | * Match.type< |
| 1108 | * { _tag: "A"; a: string } | { _tag: "B"; b: number } | { |
| 1109 | * _tag: "C" |
| 1110 | * c: boolean |
| 1111 | * } |
| 1112 | * >(), |
| 1113 | * Match.tags({ |
| 1114 | * A: (a) => a.a, |
| 1115 | * B: (b) => b.b, |
| 1116 | * C: (c) => c.c |
| 1117 | * }), |
| 1118 | * Match.exhaustive |
| 1119 | * ) |
| 1120 | * match({ _tag: "A", a: "ok" }) // => "ok" |
| 1121 | * ``` |
| 1122 | * |
| 1123 | * @category defining patterns |
| 1124 | * @since 4.0.0 |
| 1125 | */ |
| 1126 | export const tags: < |
| 1127 | R, |
| 1128 | Ret, |
| 1129 | P extends |
| 1130 | & PartialTagHandlers<"_tag", R, Ret> |
| 1131 | & { readonly [Tag in Exclude<keyof P, Types.Tags<"_tag", R>>]: never } |
| 1132 | >( |
| 1133 | fields: Contextual<P, PartialTagHandlers<"_tag", R, Ret>> |
| 1134 | ) => <I, F, A, Pr>( |
| 1135 | self: Matcher<I, F, R, A, Pr, Ret> |
| 1136 | ) => Matcher< |
| 1137 | I, |
| 1138 | Types.AddWithout<F, Extract<R, Record<"_tag", keyof P>>>, |
| 1139 | Types.ApplyFilters<I, Types.AddWithout<F, Extract<R, Record<"_tag", keyof P>>>>, |
| 1140 | A | ReturnType<P[keyof P] & {}>, |
| 1141 | Pr, |
| 1142 | Ret |
| 1143 | > = internal.tags |
| 1144 | |
| 1145 | /** |
| 1146 | * Matches values based on their `_tag` field and requires handling of all |
| 1147 | * possible cases. |
| 1148 | * |
| 1149 | * **Details** |
| 1150 | * |
| 1151 | * This function is designed for **discriminated unions** where every possible |
| 1152 | * `_tag` value must have a corresponding handler. Unlike {@link tags}, this |
| 1153 | * function ensures **exhaustiveness**, meaning all cases must be explicitly |
| 1154 | * handled. If a `_tag` value is missing from the mapping, TypeScript will |
| 1155 | * report an error. |
| 1156 | * |
| 1157 | * **Example** (Handling all tag cases) |
| 1158 | * |
| 1159 | * ```ts import.meta.vitest |
| 1160 | * import { Match, pipe } from "effect" |
| 1161 | * |
| 1162 | * const match = pipe( |
| 1163 | * Match.type< |
| 1164 | * { _tag: "A"; a: string } | { _tag: "B"; b: number } | { |
| 1165 | * _tag: "C" |
| 1166 | * c: boolean |
| 1167 | * } |
| 1168 | * >(), |
| 1169 | * Match.tagsExhaustive({ |
| 1170 | * A: (a) => a.a, |
| 1171 | * B: (b) => b.b, |
| 1172 | * C: (c) => c.c |
| 1173 | * }) |
| 1174 | * ) |
| 1175 | * match({ _tag: "B", b: 42 }) // => 42 |
| 1176 | * ``` |
| 1177 | * |
| 1178 | * @category defining patterns |
| 1179 | * @since 4.0.0 |
| 1180 | */ |
| 1181 | export const tagsExhaustive: < |
| 1182 | R, |
| 1183 | Ret, |
| 1184 | P extends |
| 1185 | & TagHandlers<"_tag", R, Ret> |
| 1186 | & { readonly [Tag in Exclude<keyof P, Types.Tags<"_tag", R>>]: never } |
| 1187 | >( |
| 1188 | fields: Contextual<P, TagHandlers<"_tag", R, Ret>> |
| 1189 | ) => <I, F, A, Pr>( |
| 1190 | self: Matcher<I, F, R, A, Pr, Ret> |
| 1191 | ) => [Pr] extends [never] ? (u: I) => Unify<A | ReturnType<P[keyof P]>> : Unify<A | ReturnType<P[keyof P]>> = |
| 1192 | internal.tagsExhaustive |
| 1193 | |
| 1194 | /** |
| 1195 | * Creates a pattern that excludes a specific value while allowing all others. |
| 1196 | * |
| 1197 | * **When to use** |
| 1198 | * |
| 1199 | * Use to add a negative pattern case for inputs that should match when another |
| 1200 | * pattern does not. |
| 1201 | * |
| 1202 | * **Details** |
| 1203 | * |
| 1204 | * Any excluded value bypasses the provided function and continues matching |
| 1205 | * through later cases. |
| 1206 | * |
| 1207 | * **Example** (Ignoring a specific value) |
| 1208 | * |
| 1209 | * ```ts import.meta.vitest |
| 1210 | * import { Match } from "effect" |
| 1211 | * |
| 1212 | * // Create a matcher for string or number values |
| 1213 | * const match = Match.type<string | number>().pipe( |
| 1214 | * // Match any value except "hi", returning "ok" |
| 1215 | * Match.not("hi", () => "ok"), |
| 1216 | * // Fallback case for when the value is "hi" |
| 1217 | * Match.orElse(() => "fallback") |
| 1218 | * ) |
| 1219 | * |
| 1220 | * match("hello") // => "ok" |
| 1221 | * |
| 1222 | * match("hi") // => "fallback" |
| 1223 | * ``` |
| 1224 | * |
| 1225 | * @see {@link when} for adding a positive pattern case |
| 1226 | * |
| 1227 | * @category defining patterns |
| 1228 | * @since 4.0.0 |
| 1229 | */ |
| 1230 | export const not: < |
| 1231 | R, |
| 1232 | const P extends Types.PatternPrimitive<R> | Types.PatternBase<R>, |
| 1233 | Ret, |
| 1234 | Args extends Array<any>, |
| 1235 | Fn extends (_: Types.NotMatch<R, P>, ...args: Args) => Ret |
| 1236 | >( |
| 1237 | pattern: P, |
| 1238 | f: Fn |
| 1239 | ) => <I, F, A, Pr>( |
| 1240 | self: Matcher<I, F, R, A, Pr, Ret, Args> |
| 1241 | ) => Matcher< |
| 1242 | I, |
| 1243 | Types.AddOnly<F, Types.WhenMatch<R, P>>, |
| 1244 | Types.ApplyFilters<I, Types.AddOnly<F, Types.WhenMatch<R, P>>>, |
| 1245 | A | ReturnType<Fn>, |
| 1246 | Pr, |
| 1247 | Ret, |
| 1248 | Args |
| 1249 | > = internal.not |
| 1250 | |
| 1251 | /** |
| 1252 | * Matches non-empty strings. |
| 1253 | * |
| 1254 | * **When to use** |
| 1255 | * |
| 1256 | * Use to match strings whose length is greater than zero. |
| 1257 | * |
| 1258 | * **Details** |
| 1259 | * |
| 1260 | * This predicate matches any string that contains at least one character, |
| 1261 | * effectively filtering out empty strings (""). |
| 1262 | * |
| 1263 | * **Example** (Matching non-empty strings) |
| 1264 | * |
| 1265 | * ```ts import.meta.vitest |
| 1266 | * import { Match } from "effect" |
| 1267 | * |
| 1268 | * const processInput = Match.type<string>() |
| 1269 | * .pipe( |
| 1270 | * Match.when(Match.nonEmptyString, (str) => `Valid input: ${str}`), |
| 1271 | * Match.orElse(() => "Input cannot be empty") |
| 1272 | * ) |
| 1273 | * |
| 1274 | * processInput("hello") // => "Valid input: hello" |
| 1275 | * |
| 1276 | * processInput("") // => "Input cannot be empty" |
| 1277 | * |
| 1278 | * processInput(" ") // => "Valid input: " |
| 1279 | * ``` |
| 1280 | * |
| 1281 | * @see {@link string} for matching any string |
| 1282 | * |
| 1283 | * @category guards |
| 1284 | * @since 4.0.0 |
| 1285 | */ |
| 1286 | export const nonEmptyString: SafeRefinement<string, never> = internal.nonEmptyString |
| 1287 | |
| 1288 | /** |
| 1289 | * Matches a specific set of literal values (e.g., `Match.is("a", 42, true)`). |
| 1290 | * |
| 1291 | * **When to use** |
| 1292 | * |
| 1293 | * Use to match one of several literal primitive or null values. |
| 1294 | * |
| 1295 | * **Details** |
| 1296 | * |
| 1297 | * This function creates a predicate that matches any of the provided literal values. |
| 1298 | * It's useful for matching against multiple specific values in a single pattern. |
| 1299 | * |
| 1300 | * **Example** (Matching literal values) |
| 1301 | * |
| 1302 | * ```ts import.meta.vitest |
| 1303 | * import { Match } from "effect" |
| 1304 | * |
| 1305 | * const handleStatus = Match.type<string | number>() |
| 1306 | * .pipe( |
| 1307 | * Match.when(Match.is("success", "ok", 200), () => "Operation successful"), |
| 1308 | * Match.when(Match.is("error", "failed", 500), () => "Operation failed"), |
| 1309 | * Match.when(Match.is(0, false, null), () => "Falsy value"), |
| 1310 | * Match.orElse((value) => `Unknown status: ${value}`) |
| 1311 | * ) |
| 1312 | * |
| 1313 | * handleStatus("success") // => "Operation successful" |
| 1314 | * |
| 1315 | * handleStatus(200) // => "Operation successful" |
| 1316 | * |
| 1317 | * handleStatus("failed") // => "Operation failed" |
| 1318 | * |
| 1319 | * handleStatus(0) // => "Falsy value" |
| 1320 | * |
| 1321 | * handleStatus("pending") // => "Unknown status: pending" |
| 1322 | * ``` |
| 1323 | * |
| 1324 | * @category guards |
| 1325 | * @since 4.0.0 |
| 1326 | */ |
| 1327 | export const is: < |
| 1328 | Literals extends ReadonlyArray<string | number | bigint | boolean | null> |
| 1329 | >(...literals: Literals) => SafeRefinement<Literals[number]> = internal.is |
| 1330 | |
| 1331 | /** |
| 1332 | * Matches values of type `string`. |
| 1333 | * |
| 1334 | * **Details** |
| 1335 | * |
| 1336 | * This predicate refines unknown values to strings, allowing pattern matching |
| 1337 | * on string types. It's commonly used in type-based matchers to handle string cases. |
| 1338 | * |
| 1339 | * **Example** (Matching string values) |
| 1340 | * |
| 1341 | * ```ts import.meta.vitest |
| 1342 | * import { Match } from "effect" |
| 1343 | * |
| 1344 | * const processValue = Match.type<string | number | boolean>().pipe( |
| 1345 | * Match.when(Match.string, (str) => `String: ${str.toUpperCase()}`), |
| 1346 | * Match.when(Match.number, (num) => `Number: ${num * 2}`), |
| 1347 | * Match.when(Match.boolean, (bool) => `Boolean: ${bool ? "yes" : "no"}`), |
| 1348 | * Match.exhaustive |
| 1349 | * ) |
| 1350 | * |
| 1351 | * processValue("hello") // => "String: HELLO" |
| 1352 | * processValue(42) // => "Number: 84" |
| 1353 | * processValue(true) // => "Boolean: yes" |
| 1354 | * ``` |
| 1355 | * |
| 1356 | * @category guards |
| 1357 | * @since 4.0.0 |
| 1358 | */ |
| 1359 | export const string: Predicate.Refinement<unknown, string> = Predicate.isString |
| 1360 | |
| 1361 | /** |
| 1362 | * Matches values of type `number`. |
| 1363 | * |
| 1364 | * **When to use** |
| 1365 | * |
| 1366 | * Use to match primitive number values, including `NaN` and infinities. |
| 1367 | * |
| 1368 | * **Details** |
| 1369 | * |
| 1370 | * This predicate refines unknown values to numbers, allowing pattern matching |
| 1371 | * on numeric types. It matches all number values including integers, floats, |
| 1372 | * `Infinity`, `-Infinity`, and `NaN`. |
| 1373 | * |
| 1374 | * **Example** (Matching number values) |
| 1375 | * |
| 1376 | * ```ts import.meta.vitest |
| 1377 | * import { Match } from "effect" |
| 1378 | * |
| 1379 | * const categorizeNumber = Match.type<unknown>().pipe( |
| 1380 | * Match.when(Match.number, (num) => { |
| 1381 | * if (Number.isNaN(num)) return "Not a number" |
| 1382 | * if (!Number.isFinite(num)) return "Infinite" |
| 1383 | * if (Number.isInteger(num)) return `Integer: ${num}` |
| 1384 | * return `Float: ${num.toFixed(2)}` |
| 1385 | * }), |
| 1386 | * Match.orElse(() => "Not a number type") |
| 1387 | * ) |
| 1388 | * |
| 1389 | * categorizeNumber(42) // => "Integer: 42" |
| 1390 | * categorizeNumber(3.14) // => "Float: 3.14" |
| 1391 | * categorizeNumber(NaN) // => "Not a number" |
| 1392 | * categorizeNumber("hello") // => "Not a number type" |
| 1393 | * ``` |
| 1394 | * |
| 1395 | * @see {@link bigint} for matching primitive bigint values |
| 1396 | * |
| 1397 | * @category guards |
| 1398 | * @since 4.0.0 |
| 1399 | */ |
| 1400 | export const number: Predicate.Refinement<unknown, number> = Predicate.isNumber |
| 1401 | |
| 1402 | /** |
| 1403 | * Matches any value without restrictions. |
| 1404 | * |
| 1405 | * **When to use** |
| 1406 | * |
| 1407 | * Use to define an explicit catch-all pattern when the handler should receive |
| 1408 | * the unmatched value. |
| 1409 | * |
| 1410 | * **Details** |
| 1411 | * |
| 1412 | * This predicate matches every input, including `undefined`, `null`, objects, |
| 1413 | * primitives, and functions. |
| 1414 | * |
| 1415 | * **Gotchas** |
| 1416 | * |
| 1417 | * `Match.any` should usually be last because cases are checked in order and |
| 1418 | * the first matching case wins. |
| 1419 | * |
| 1420 | * **Example** (Matching any remaining value) |
| 1421 | * |
| 1422 | * ```ts import.meta.vitest |
| 1423 | * import { Match } from "effect" |
| 1424 | * |
| 1425 | * const describeValue = Match.type<unknown>() |
| 1426 | * .pipe( |
| 1427 | * Match.when(Match.string, (str) => `String: ${str}`), |
| 1428 | * Match.when(Match.number, (num) => `Number: ${num}`), |
| 1429 | * Match.when(Match.boolean, (bool) => `Boolean: ${bool}`), |
| 1430 | * Match.when(Match.any, (value) => `Other: ${typeof value}`), |
| 1431 | * Match.exhaustive |
| 1432 | * ) |
| 1433 | * |
| 1434 | * describeValue("hello") // => "String: hello" |
| 1435 | * |
| 1436 | * describeValue(42) // => "Number: 42" |
| 1437 | * |
| 1438 | * describeValue([1, 2, 3]) // => "Other: object" |
| 1439 | * |
| 1440 | * describeValue(null) // => "Other: object" |
| 1441 | * ``` |
| 1442 | * |
| 1443 | * @see {@link defined} for matching only non-nullish values |
| 1444 | * @see {@link orElse} for providing a fallback after earlier cases |
| 1445 | * |
| 1446 | * @category guards |
| 1447 | * @since 4.0.0 |
| 1448 | */ |
| 1449 | export const any: SafeRefinement<unknown, any> = internal.any |
| 1450 | |
| 1451 | /** |
| 1452 | * Matches any defined (non-null and non-undefined) value. |
| 1453 | * |
| 1454 | * **When to use** |
| 1455 | * |
| 1456 | * Use to exclude only `null` and `undefined` from a match branch. |
| 1457 | * |
| 1458 | * **Details** |
| 1459 | * |
| 1460 | * This predicate matches values that are neither `null` nor `undefined`, |
| 1461 | * effectively filtering out nullish values while preserving all other types. |
| 1462 | * |
| 1463 | * **Example** (Matching defined values) |
| 1464 | * |
| 1465 | * ```ts import.meta.vitest |
| 1466 | * import { Match } from "effect" |
| 1467 | * |
| 1468 | * const processValue = Match.type<string | number | null | undefined>() |
| 1469 | * .pipe( |
| 1470 | * Match.when(Match.defined, (value) => `Defined value: ${value}`), |
| 1471 | * Match.orElse(() => "Value is null or undefined") |
| 1472 | * ) |
| 1473 | * |
| 1474 | * processValue("hello") // => "Defined value: hello" |
| 1475 | * |
| 1476 | * processValue(42) // => "Defined value: 42" |
| 1477 | * |
| 1478 | * processValue(0) // => "Defined value: 0" |
| 1479 | * |
| 1480 | * processValue("") // => "Defined value: " |
| 1481 | * |
| 1482 | * processValue(null) // => "Value is null or undefined" |
| 1483 | * |
| 1484 | * processValue(undefined) // => "Value is null or undefined" |
| 1485 | * ``` |
| 1486 | * |
| 1487 | * @see {@link any} for matching every value without excluding nullish inputs |
| 1488 | * |
| 1489 | * @category guards |
| 1490 | * @since 4.0.0 |
| 1491 | */ |
| 1492 | export const defined: <A>(u: A) => u is A & {} = internal.defined |
| 1493 | |
| 1494 | /** |
| 1495 | * Matches values of type `boolean`. |
| 1496 | * |
| 1497 | * **When to use** |
| 1498 | * |
| 1499 | * Use to match primitive boolean values. |
| 1500 | * |
| 1501 | * **Details** |
| 1502 | * |
| 1503 | * This predicate refines unknown values to booleans, allowing pattern matching |
| 1504 | * on boolean types. It only matches the primitive boolean values `true` and `false`. |
| 1505 | * |
| 1506 | * **Example** (Matching boolean values) |
| 1507 | * |
| 1508 | * ```ts import.meta.vitest |
| 1509 | * import { Match } from "effect" |
| 1510 | * |
| 1511 | * const describeTruthiness = Match.type<unknown>().pipe( |
| 1512 | * Match.when( |
| 1513 | * Match.boolean, |
| 1514 | * (bool) => bool ? "Definitely true" : "Definitely false" |
| 1515 | * ), |
| 1516 | * Match.when(0, () => "Falsy number"), |
| 1517 | * Match.when("", () => "Empty string"), |
| 1518 | * Match.when(Match.null, () => "Null value"), |
| 1519 | * Match.orElse(() => "Some other truthy value") |
| 1520 | * ) |
| 1521 | * |
| 1522 | * describeTruthiness(true) // => "Definitely true" |
| 1523 | * describeTruthiness(false) // => "Definitely false" |
| 1524 | * describeTruthiness(0) // => "Falsy number" |
| 1525 | * describeTruthiness(1) // => "Some other truthy value" |
| 1526 | * ``` |
| 1527 | * |
| 1528 | * @see {@link is} for matching specific literal boolean values |
| 1529 | * |
| 1530 | * @category guards |
| 1531 | * @since 4.0.0 |
| 1532 | */ |
| 1533 | export const boolean: Predicate.Refinement<unknown, boolean> = Predicate.isBoolean |
| 1534 | |
| 1535 | const _undefined: Predicate.Refinement<unknown, undefined> = Predicate.isUndefined |
| 1536 | export { |
| 1537 | /** |
| 1538 | * Matches the value `undefined`. |
| 1539 | * |
| 1540 | * **When to use** |
| 1541 | * |
| 1542 | * Use when a matcher should handle only inputs with no defined value. |
| 1543 | * |
| 1544 | * **Details** |
| 1545 | * |
| 1546 | * This refinement is backed by `Predicate.isUndefined`, which checks |
| 1547 | * `input === undefined`. |
| 1548 | * |
| 1549 | * @see {@link defined} for matching non-nullish values |
| 1550 | * @see {@link is} for matching literal values |
| 1551 | * |
| 1552 | * @category guards |
| 1553 | * @since 4.0.0 |
| 1554 | */ |
| 1555 | _undefined as undefined |
| 1556 | } |
| 1557 | |
| 1558 | const _null: Predicate.Refinement<unknown, null> = Predicate.isNull |
| 1559 | export { |
| 1560 | /** |
| 1561 | * Matches the value `null`. |
| 1562 | * |
| 1563 | * **When to use** |
| 1564 | * |
| 1565 | * Use to handle only the `null` literal in a match branch. |
| 1566 | * |
| 1567 | * **Details** |
| 1568 | * |
| 1569 | * This refinement is backed by `Predicate.isNull`, which checks |
| 1570 | * `input === null`. |
| 1571 | * |
| 1572 | * @see {@link defined} for matching non-nullish values |
| 1573 | * @see {@link is} for matching literal values |
| 1574 | * |
| 1575 | * @category guards |
| 1576 | * @since 4.0.0 |
| 1577 | */ |
| 1578 | _null as null |
| 1579 | } |
| 1580 | |
| 1581 | /** |
| 1582 | * Matches values of type `bigint`. |
| 1583 | * |
| 1584 | * **When to use** |
| 1585 | * |
| 1586 | * Use to match primitive bigint values. |
| 1587 | * |
| 1588 | * **Details** |
| 1589 | * |
| 1590 | * This predicate refines unknown values to bigints, allowing pattern matching |
| 1591 | * on bigint types. BigInts are used for representing integers with arbitrary precision. |
| 1592 | * |
| 1593 | * **Example** (Matching bigint values) |
| 1594 | * |
| 1595 | * ```ts import.meta.vitest |
| 1596 | * import { Match } from "effect" |
| 1597 | * |
| 1598 | * const processLargeNumber = Match.type<unknown>().pipe( |
| 1599 | * Match.when(Match.bigint, (big) => { |
| 1600 | * if (big > 9007199254740991n) { |
| 1601 | * return `Large integer: ${big.toString()}` |
| 1602 | * } |
| 1603 | * return `BigInt: ${big.toString()}` |
| 1604 | * }), |
| 1605 | * Match.when(Match.number, (num) => `Regular number: ${num}`), |
| 1606 | * Match.orElse(() => "Not a numeric type") |
| 1607 | * ) |
| 1608 | * |
| 1609 | * processLargeNumber(123n) // => "BigInt: 123" |
| 1610 | * processLargeNumber(9007199254740992n) // => "Large integer: 9007199254740992" |
| 1611 | * processLargeNumber(123) // => "Regular number: 123" |
| 1612 | * processLargeNumber("123") // => "Not a numeric type" |
| 1613 | * ``` |
| 1614 | * |
| 1615 | * @see {@link number} for matching primitive number values |
| 1616 | * |
| 1617 | * @category guards |
| 1618 | * @since 4.0.0 |
| 1619 | */ |
| 1620 | export const bigint: Predicate.Refinement<unknown, bigint> = Predicate.isBigInt |
| 1621 | |
| 1622 | /** |
| 1623 | * Matches values of type `symbol`. |
| 1624 | * |
| 1625 | * **Details** |
| 1626 | * |
| 1627 | * This predicate refines unknown values to symbols, allowing pattern matching |
| 1628 | * on symbol types. Symbols are unique identifiers that are often used as |
| 1629 | * object keys or for creating private properties. |
| 1630 | * |
| 1631 | * **Example** (Matching symbol values) |
| 1632 | * |
| 1633 | * ```ts import.meta.vitest |
| 1634 | * import { Match } from "effect" |
| 1635 | * |
| 1636 | * const mySymbol = Symbol("my-symbol") |
| 1637 | * const globalSymbol = Symbol.for("global-symbol") |
| 1638 | * |
| 1639 | * const handleSymbol = Match.type<unknown>().pipe( |
| 1640 | * Match.when(Match.symbol, (sym) => { |
| 1641 | * const description = sym.description |
| 1642 | * if (description) { |
| 1643 | * return `Symbol with description: ${description}` |
| 1644 | * } |
| 1645 | * return "Symbol without description" |
| 1646 | * }), |
| 1647 | * Match.orElse(() => "Not a symbol") |
| 1648 | * ) |
| 1649 | * |
| 1650 | * handleSymbol(mySymbol) // => "Symbol with description: my-symbol" |
| 1651 | * handleSymbol(Symbol()) // => "Symbol without description" |
| 1652 | * handleSymbol("string") // => "Not a symbol" |
| 1653 | * ``` |
| 1654 | * |
| 1655 | * @category guards |
| 1656 | * @since 4.0.0 |
| 1657 | */ |
| 1658 | export const symbol: Predicate.Refinement<unknown, symbol> = Predicate.isSymbol |
| 1659 | |
| 1660 | /** |
| 1661 | * Matches values that are instances of `Date`. |
| 1662 | * |
| 1663 | * **When to use** |
| 1664 | * |
| 1665 | * Use to match `Date` instances. |
| 1666 | * |
| 1667 | * **Details** |
| 1668 | * |
| 1669 | * This predicate refines unknown values to Date instances, allowing pattern |
| 1670 | * matching on Date objects. It only matches actual Date instances, not |
| 1671 | * date strings or timestamps. |
| 1672 | * |
| 1673 | * **Example** (Matching Date instances) |
| 1674 | * |
| 1675 | * ```ts import.meta.vitest |
| 1676 | * import { Match } from "effect" |
| 1677 | * |
| 1678 | * const processDateValue = Match.type<unknown>().pipe( |
| 1679 | * Match.when(Match.date, (date) => { |
| 1680 | * if (isNaN(date.getTime())) { |
| 1681 | * return "Invalid date" |
| 1682 | * } |
| 1683 | * return `Date: ${date.toISOString().split("T")[0]}` |
| 1684 | * }), |
| 1685 | * Match.when(Match.string, (str) => `Date string: ${str}`), |
| 1686 | * Match.orElse(() => "Not a date-related value") |
| 1687 | * ) |
| 1688 | * |
| 1689 | * processDateValue(new Date("2024-01-01")) // => "Date: 2024-01-01" |
| 1690 | * processDateValue(new Date("invalid")) // => "Invalid date" |
| 1691 | * processDateValue("2024-01-01") // => "Date string: 2024-01-01" |
| 1692 | * processDateValue(1704067200000) // => "Not a date-related value" |
| 1693 | * ``` |
| 1694 | * |
| 1695 | * @see {@link instanceOf} for matching instances of any constructor |
| 1696 | * |
| 1697 | * @category guards |
| 1698 | * @since 4.0.0 |
| 1699 | */ |
| 1700 | export const date: Predicate.Refinement<unknown, Date> = Predicate.isDate |
| 1701 | |
| 1702 | /** |
| 1703 | * Matches non-null objects other than arrays. |
| 1704 | * |
| 1705 | * **When to use** |
| 1706 | * |
| 1707 | * Use to match broad non-null, non-array object values. |
| 1708 | * |
| 1709 | * **Details** |
| 1710 | * |
| 1711 | * This predicate uses `Predicate.isObject`: it returns `true` for values whose |
| 1712 | * runtime type is `"object"`, are not `null`, and are not arrays. It can match |
| 1713 | * `Date`, `RegExp`, and class instances; use `instanceOf` or a more specific |
| 1714 | * pattern when those cases need to be distinguished. |
| 1715 | * |
| 1716 | * **Example** (Matching record objects) |
| 1717 | * |
| 1718 | * ```ts import.meta.vitest |
| 1719 | * import { Match } from "effect" |
| 1720 | * |
| 1721 | * const analyzeValue = Match.type<unknown>().pipe( |
| 1722 | * Match.when(Match.record, (obj) => { |
| 1723 | * const keys = Object.keys(obj) |
| 1724 | * const valueCount = keys.length |
| 1725 | * return `Object with ${valueCount} properties: [${keys.join(", ")}]` |
| 1726 | * }), |
| 1727 | * Match.when( |
| 1728 | * Match.instanceOf(Array), |
| 1729 | * (arr) => `Array with ${arr.length} items` |
| 1730 | * ), |
| 1731 | * Match.orElse(() => "Not an object") |
| 1732 | * ) |
| 1733 | * |
| 1734 | * analyzeValue({ name: "Alice", age: 30 }) // => "Object with 2 properties: [name, age]" |
| 1735 | * analyzeValue([1, 2, 3]) // => "Array with 3 items" |
| 1736 | * analyzeValue(null) // => "Not an object" |
| 1737 | * analyzeValue("hello") // => "Not an object" |
| 1738 | * ``` |
| 1739 | * |
| 1740 | * @see {@link instanceOf} for matching a specific constructor |
| 1741 | * |
| 1742 | * @category guards |
| 1743 | * @since 4.0.0 |
| 1744 | */ |
| 1745 | export const record: Predicate.Refinement<unknown, { [x: PropertyKey]: unknown }> = Predicate.isObject |
| 1746 | |
| 1747 | /** |
| 1748 | * Matches instances of a given class. |
| 1749 | * |
| 1750 | * **When to use** |
| 1751 | * |
| 1752 | * Use to match values that are instances of a constructor with type-safe |
| 1753 | * narrowing. |
| 1754 | * |
| 1755 | * **Details** |
| 1756 | * |
| 1757 | * This predicate checks if a value is an instance of the specified constructor, |
| 1758 | * providing type-safe matching for class instances and built-in objects. |
| 1759 | * |
| 1760 | * **Example** (Matching class instances) |
| 1761 | * |
| 1762 | * ```ts import.meta.vitest |
| 1763 | * import { Match } from "effect" |
| 1764 | * |
| 1765 | * class CustomError extends Error { |
| 1766 | * constructor(message: string, public code: number) { |
| 1767 | * super(message) |
| 1768 | * } |
| 1769 | * } |
| 1770 | * |
| 1771 | * const handleValue = Match.type<unknown>() |
| 1772 | * .pipe( |
| 1773 | * Match.when( |
| 1774 | * Match.instanceOf(CustomError), |
| 1775 | * (err) => `Custom error: ${err.message} (code: ${err.code})` |
| 1776 | * ), |
| 1777 | * Match.when( |
| 1778 | * Match.instanceOf(Error), |
| 1779 | * (err) => `Standard error: ${err.message}` |
| 1780 | * ), |
| 1781 | * Match.when( |
| 1782 | * Match.instanceOf(Array), |
| 1783 | * (arr) => `Array with ${arr.length} items` |
| 1784 | * ), |
| 1785 | * Match.when( |
| 1786 | * Match.instanceOf(Map), |
| 1787 | * (map) => `Map with ${map.size} entries` |
| 1788 | * ), |
| 1789 | * Match.orElse((value) => `Other: ${typeof value}`) |
| 1790 | * ) |
| 1791 | * |
| 1792 | * handleValue(new CustomError("Failed", 404)) // => "Custom error: Failed (code: 404)" |
| 1793 | * handleValue(new Error("Generic error")) // => "Standard error: Generic error" |
| 1794 | * handleValue([1, 2, 3]) // => "Array with 3 items" |
| 1795 | * handleValue(new Map([["count", 1]])) // => "Map with 1 entries" |
| 1796 | * ``` |
| 1797 | * |
| 1798 | * @see {@link instanceOfUnsafe} for constructor matching without the same type-safety guarantee |
| 1799 | * @see {@link record} for matching broad non-null, non-array objects |
| 1800 | * |
| 1801 | * @category guards |
| 1802 | * @since 4.0.0 |
| 1803 | */ |
| 1804 | export const instanceOf: <A extends abstract new(...args: any) => any>( |
| 1805 | constructor: A |
| 1806 | ) => SafeRefinement<InstanceType<A>, never> = internal.instanceOf |
| 1807 | |
| 1808 | /** |
| 1809 | * Checks whether a value is an instance of a constructor without type-safe narrowing. |
| 1810 | * |
| 1811 | * **When to use** |
| 1812 | * |
| 1813 | * Use when you need constructor matching to use the unsafe refinement type. |
| 1814 | * |
| 1815 | * **Details** |
| 1816 | * |
| 1817 | * This predicate checks if a value is an instance of the specified constructor |
| 1818 | * but doesn't provide the same type safety guarantees as the regular `instanceOf`. |
| 1819 | * Use this when you need more flexibility but understand the type safety implications. |
| 1820 | * |
| 1821 | * **Example** (Matching class instances unsafely) |
| 1822 | * |
| 1823 | * ```ts import.meta.vitest |
| 1824 | * import { Match } from "effect" |
| 1825 | * |
| 1826 | * class CustomError extends Error { |
| 1827 | * constructor(message: string, public code: number) { |
| 1828 | * super(message) |
| 1829 | * } |
| 1830 | * } |
| 1831 | * |
| 1832 | * // When you need to match instances but handle type narrowing manually |
| 1833 | * const handleError = Match.type<unknown>().pipe( |
| 1834 | * Match.when(Match.instanceOfUnsafe(CustomError), (err: any) => { |
| 1835 | * // Manual type assertion needed |
| 1836 | * const customErr = err as CustomError |
| 1837 | * return `Custom error ${customErr.code}: ${customErr.message}` |
| 1838 | * }), |
| 1839 | * Match.orElse(() => "Not a CustomError") |
| 1840 | * ) |
| 1841 | * handleError(new CustomError("failed", 500)) // => "Custom error 500: failed" |
| 1842 | * ``` |
| 1843 | * |
| 1844 | * @see {@link instanceOf} for type-safe constructor matching |
| 1845 | * |
| 1846 | * @category guards |
| 1847 | * @since 4.0.0 |
| 1848 | */ |
| 1849 | export const instanceOfUnsafe: <A extends abstract new(...args: any) => any>( |
| 1850 | constructor: A |
| 1851 | ) => SafeRefinement<InstanceType<A>, InstanceType<A>> = internal.instanceOf |
| 1852 | |
| 1853 | /** |
| 1854 | * Provides a fallback value when no patterns match. |
| 1855 | * |
| 1856 | * **When to use** |
| 1857 | * |
| 1858 | * Use to finalize a matcher with a fallback for unmatched input. |
| 1859 | * |
| 1860 | * **Details** |
| 1861 | * |
| 1862 | * This function ensures that a matcher always returns a valid result, even if |
| 1863 | * no defined patterns match. It acts as a default case, similar to the |
| 1864 | * `default` clause in a `switch` statement or the final `else` in an `if-else` |
| 1865 | * chain. |
| 1866 | * |
| 1867 | * **Example** (Providing a default value when no patterns match) |
| 1868 | * |
| 1869 | * ```ts import.meta.vitest |
| 1870 | * import { Match } from "effect" |
| 1871 | * |
| 1872 | * // Create a matcher for string or number values |
| 1873 | * const match = Match.type<string | number>().pipe( |
| 1874 | * // Match when the value is "a" |
| 1875 | * Match.when("a", () => "ok"), |
| 1876 | * // Fallback when no patterns match |
| 1877 | * Match.orElse(() => "fallback") |
| 1878 | * ) |
| 1879 | * |
| 1880 | * match("a") // => "ok" |
| 1881 | * |
| 1882 | * match("b") // => "fallback" |
| 1883 | * ``` |
| 1884 | * |
| 1885 | * @see {@link option} for finalizing unmatched input as `Option.none` |
| 1886 | * @see {@link result} for returning unmatched input as a `Result` failure |
| 1887 | * @see {@link orElseAbsurd} for finalizing when unmatched input should be impossible |
| 1888 | * |
| 1889 | * @category completion |
| 1890 | * @since 4.0.0 |
| 1891 | */ |
| 1892 | export const orElse: <RA, Ret, Args extends Array<any>, F extends (_: RA, ...args: Args) => Ret>( |
| 1893 | f: F |
| 1894 | ) => <I, R, A, Pr>( |
| 1895 | self: Matcher<I, R, RA, A, Pr, Ret, Args> |
| 1896 | ) => [Pr] extends [never] ? [Args] extends [[]] ? (input: I) => Unify<ReturnType<F> | A> |
| 1897 | : (...args: Args) => Unify<ReturnType<F> | A> |
| 1898 | : Unify<ReturnType<F> | A> = internal.orElse |
| 1899 | |
| 1900 | // TODO(4.0): Rename to "orThrow"? Like Result.getOrThrow |
| 1901 | /** |
| 1902 | * Returns a matcher that throws an error if no pattern matches. |
| 1903 | * |
| 1904 | * **When to use** |
| 1905 | * |
| 1906 | * Use to finalize a matcher when every remaining unmatched case should be |
| 1907 | * impossible. |
| 1908 | * |
| 1909 | * **Details** |
| 1910 | * |
| 1911 | * This function finalizes a matcher by ensuring that if no patterns match, an |
| 1912 | * error is thrown. It is useful when all cases should be covered, and any |
| 1913 | * unexpected input should trigger an error instead of returning a default |
| 1914 | * value. |
| 1915 | * |
| 1916 | * When used, this function removes the need for an explicit fallback case and |
| 1917 | * ensures that an unmatched value is never silently ignored. |
| 1918 | * |
| 1919 | * **Example** (Throwing on unmatched input) |
| 1920 | * |
| 1921 | * ```ts import.meta.vitest |
| 1922 | * import { Match } from "effect" |
| 1923 | * |
| 1924 | * const strictMatcher = Match.type<"a" | "b">().pipe( |
| 1925 | * Match.when("a", () => "Found A"), |
| 1926 | * Match.when("b", () => "Found B"), |
| 1927 | * // Will throw if input is neither "a" nor "b" |
| 1928 | * Match.orElseAbsurd |
| 1929 | * ) |
| 1930 | * |
| 1931 | * strictMatcher("a") // => "Found A" |
| 1932 | * strictMatcher("b") // => "Found B" |
| 1933 | * |
| 1934 | * // This would throw an error at runtime: |
| 1935 | * // strictMatcher("c" as any) // throws |
| 1936 | * ``` |
| 1937 | * |
| 1938 | * @see {@link exhaustive} for compile-time exhaustive matcher finalization |
| 1939 | * @see {@link orElse} for providing a fallback for unmatched input |
| 1940 | * |
| 1941 | * @category completion |
| 1942 | * @since 4.0.0 |
| 1943 | */ |
| 1944 | export const orElseAbsurd: <I, R, RA, A, Pr, Ret, Args extends Array<any>>( |
| 1945 | self: Matcher<I, R, RA, A, Pr, Ret, Args> |
| 1946 | ) => [Pr] extends [never] ? [Args] extends [[]] ? (input: I) => Unify<A> : (...args: Args) => Unify<A> : Unify<A> = |
| 1947 | internal.orElseAbsurd |
| 1948 | |
| 1949 | /** |
| 1950 | * Wraps the match result in a `Result`, distinguishing matched and unmatched |
| 1951 | * cases. |
| 1952 | * |
| 1953 | * **Details** |
| 1954 | * |
| 1955 | * This function ensures that the result of a matcher is always wrapped in an |
| 1956 | * `Result`, allowing clear differentiation between successful matches |
| 1957 | * (`Ok(value)`) and cases where no pattern matched (`Err(unmatched |
| 1958 | * value)`). |
| 1959 | * |
| 1960 | * This approach is particularly useful when handling optional values or when an |
| 1961 | * unmatched case should be explicitly handled rather than returning a default |
| 1962 | * value or throwing an error. |
| 1963 | * |
| 1964 | * **Example** (Extracting a user role with `Match.result`) |
| 1965 | * |
| 1966 | * ```ts import.meta.vitest |
| 1967 | * import { Match } from "effect" |
| 1968 | * |
| 1969 | * type User = { readonly role: "admin" | "editor" | "viewer" } |
| 1970 | * |
| 1971 | * // Create a matcher to extract user roles |
| 1972 | * const getRole = Match.type<User>().pipe( |
| 1973 | * Match.when({ role: "admin" }, () => "Has full access"), |
| 1974 | * Match.when({ role: "editor" }, () => "Can edit content"), |
| 1975 | * Match.result // Wrap the result in an Result |
| 1976 | * ) |
| 1977 | * |
| 1978 | * getRole({ role: "admin" })._tag // => "Success" |
| 1979 | * |
| 1980 | * getRole({ role: "viewer" })._tag // => "Failure" |
| 1981 | * ``` |
| 1982 | * |
| 1983 | * @category completion |
| 1984 | * @since 4.0.0 |
| 1985 | */ |
| 1986 | export const result: <I, F, R, A, Pr, Ret, Args extends Array<any>>( |
| 1987 | self: Matcher<I, F, R, A, Pr, Ret, Args> |
| 1988 | ) => [Pr] extends [never] ? [Args] extends [[]] ? (input: I) => Result.Result<Unify<A>, R> |
| 1989 | : (...args: Args) => Result.Result<Unify<A>, R> |
| 1990 | : Result.Result<Unify<A>, R> = internal.result |
| 1991 | |
| 1992 | /** |
| 1993 | * Wraps the match result in an `Option`, representing an optional match. |
| 1994 | * |
| 1995 | * **When to use** |
| 1996 | * |
| 1997 | * Use to finalize a matcher when unmatched input is expected and should become |
| 1998 | * `Option.none`. |
| 1999 | * |
| 2000 | * **Details** |
| 2001 | * |
| 2002 | * This function ensures that the result of a matcher is wrapped in an `Option`, |
| 2003 | * making it easy to handle cases where no pattern matches. If a match is found, |
| 2004 | * it returns `Some(value)`, otherwise, it returns `None`. |
| 2005 | * |
| 2006 | * This is useful in cases where a missing match is expected and should be |
| 2007 | * handled explicitly rather than throwing an error or returning a default |
| 2008 | * value. |
| 2009 | * |
| 2010 | * **Example** (Extracting a user role with `Match.option`) |
| 2011 | * |
| 2012 | * ```ts import.meta.vitest |
| 2013 | * import { Match } from "effect" |
| 2014 | * |
| 2015 | * type User = { readonly role: "admin" | "editor" | "viewer" } |
| 2016 | * |
| 2017 | * // Create a matcher to extract user roles |
| 2018 | * const getRole = Match.type<User>().pipe( |
| 2019 | * Match.when({ role: "admin" }, () => "Has full access"), |
| 2020 | * Match.when({ role: "editor" }, () => "Can edit content"), |
| 2021 | * Match.option // Wrap the result in an Option |
| 2022 | * ) |
| 2023 | * |
| 2024 | * getRole({ role: "admin" })._tag // => "Some" |
| 2025 | * |
| 2026 | * getRole({ role: "viewer" })._tag // => "None" |
| 2027 | * ``` |
| 2028 | * |
| 2029 | * @see {@link result} for preserving unmatched input as a `Result` failure |
| 2030 | * @see {@link orElse} for replacing unmatched input with a fallback value |
| 2031 | * |
| 2032 | * @category completion |
| 2033 | * @since 4.0.0 |
| 2034 | */ |
| 2035 | export const option: <I, F, R, A, Pr, Ret, Args extends Array<any>>( |
| 2036 | self: Matcher<I, F, R, A, Pr, Ret, Args> |
| 2037 | ) => [Pr] extends [never] ? [Args] extends [[]] ? (input: I) => Option.Option<Unify<A>> |
| 2038 | : (...args: Args) => Option.Option<Unify<A>> |
| 2039 | : Option.Option<Unify<A>> = internal.option |
| 2040 | |
| 2041 | /** |
| 2042 | * Completes a matcher that handles every remaining input case. |
| 2043 | * |
| 2044 | * **When to use** |
| 2045 | * |
| 2046 | * Use to require TypeScript to reject incomplete matcher definitions before the |
| 2047 | * matcher is turned into a function. |
| 2048 | * |
| 2049 | * **Details** |
| 2050 | * |
| 2051 | * If any case is still unmatched, the matcher does not type-check as |
| 2052 | * exhaustive. |
| 2053 | * |
| 2054 | * **Example** (Ensuring all cases are covered) |
| 2055 | * |
| 2056 | * ```ts import.meta.vitest |
| 2057 | * import { Match } from "effect" |
| 2058 | * |
| 2059 | * // Create a matcher for string or number values |
| 2060 | * const match = Match.type<string | number>().pipe( |
| 2061 | * // Match when the value is a number |
| 2062 | * Match.when(Match.number, (n) => `number: ${n}`), |
| 2063 | * // Mark the match as exhaustive, ensuring all cases are handled |
| 2064 | * // TypeScript will throw an error if any case is missing |
| 2065 | * // @ts-expect-error Type 'string' is not assignable to type 'never' |
| 2066 | * Match.exhaustive |
| 2067 | * ) |
| 2068 | * ``` |
| 2069 | * |
| 2070 | * @category completion |
| 2071 | * @since 4.0.0 |
| 2072 | */ |
| 2073 | export const exhaustive: <I, F, A, Pr, Ret, Args extends Array<any>>( |
| 2074 | self: Matcher<I, F, never, A, Pr, Ret, Args> |
| 2075 | ) => [Pr] extends [never] ? [Args] extends [[]] ? (u: I) => Unify<A> : (...args: Args) => Unify<A> : Unify<A> = |
| 2076 | internal.exhaustive |
| 2077 | |
| 2078 | const SafeRefinementId = "~effect/Match/SafeRefinement" |
| 2079 | |
| 2080 | /** |
| 2081 | * A safe refinement that narrows types without runtime errors. |
| 2082 | * |
| 2083 | * **Details** |
| 2084 | * |
| 2085 | * `SafeRefinement` provides a way to refine types in pattern matching while |
| 2086 | * maintaining type safety. Unlike regular predicates, safe refinements can |
| 2087 | * transform the matched value's type without throwing runtime errors. |
| 2088 | * |
| 2089 | * **Example** (Using safe refinements) |
| 2090 | * |
| 2091 | * ```ts import.meta.vitest |
| 2092 | * import { Match } from "effect" |
| 2093 | * |
| 2094 | * // Built-in safe refinements |
| 2095 | * const processValue = Match.type<unknown>().pipe( |
| 2096 | * Match.when(Match.string, (s) => s.toUpperCase()), |
| 2097 | * Match.when(Match.number, (n) => n * 2), |
| 2098 | * Match.when(Match.defined, (value) => `Defined: ${value}`), |
| 2099 | * Match.orElse(() => "Undefined or null") |
| 2100 | * ) |
| 2101 | * |
| 2102 | * processValue("hello") // => "HELLO" |
| 2103 | * processValue(21) // => 42 |
| 2104 | * processValue(true) // => "Defined: true" |
| 2105 | * processValue(null) // => "Undefined or null" |
| 2106 | * ``` |
| 2107 | * |
| 2108 | * @category models |
| 2109 | * @since 4.0.0 |
| 2110 | */ |
| 2111 | export interface SafeRefinement<in A, out R = A> { |
| 2112 | readonly [SafeRefinementId]: (a: A) => R |
| 2113 | } |
| 2114 | |
| 2115 | const Fail = Symbol.for("effect/Fail") |
| 2116 | type Fail = typeof Fail |
| 2117 | |
| 2118 | /** |
| 2119 | * A namespace containing utility types for Match operations. |
| 2120 | * |
| 2121 | * **Details** |
| 2122 | * |
| 2123 | * This namespace provides advanced type-level utilities used internally by the |
| 2124 | * Match module to perform complex pattern matching, type narrowing, and filter |
| 2125 | * application. These types enable the sophisticated type inference that makes |
| 2126 | * pattern matching both type-safe and ergonomic. |
| 2127 | * |
| 2128 | * @since 4.0.0 |
| 2129 | */ |
| 2130 | export declare namespace Types { |
| 2131 | /** |
| 2132 | * Computes the matched type when a pattern P is applied to type R. |
| 2133 | * |
| 2134 | * **Details** |
| 2135 | * |
| 2136 | * This utility type determines what type a value will have after successfully |
| 2137 | * matching against a pattern. It handles refinements, predicates, and complex |
| 2138 | * object patterns to provide accurate type narrowing. |
| 2139 | * |
| 2140 | * **Example** (Computing matched types) |
| 2141 | * |
| 2142 | * ```ts import.meta.vitest |
| 2143 | * import type { Match } from "effect" |
| 2144 | * |
| 2145 | * // WhenMatch computes the narrowed type after pattern matching |
| 2146 | * type StringMatch = Match.Types.WhenMatch<string | number, typeof Match.string> |
| 2147 | * // Result: string |
| 2148 | * |
| 2149 | * type ObjectMatch = Match.Types.WhenMatch< |
| 2150 | * { type: "user"; name: string } | { |
| 2151 | * type: "admin" |
| 2152 | * permissions: Array<string> |
| 2153 | * }, |
| 2154 | * { type: "user" } |
| 2155 | * > |
| 2156 | * // Result: { type: "user"; name: string } |
| 2157 | * ``` |
| 2158 | * |
| 2159 | * @category utility types |
| 2160 | * @since 4.0.0 |
| 2161 | */ |
| 2162 | export type WhenMatch<R, P> = |
| 2163 | // check for any |
| 2164 | [0] extends [1 & R] ? ResolvePred<P> : |
| 2165 | P extends SafeRefinement<infer SP, never> ? SP |
| 2166 | : P extends Predicate.Refinement<infer _R, infer RP> |
| 2167 | // try to narrow refinement |
| 2168 | ? [Extract<R, RP>] extends [infer X] ? [X] extends [never] |
| 2169 | // fallback to original refinement |
| 2170 | ? RP |
| 2171 | : X |
| 2172 | : never |
| 2173 | : P extends PredicateA<infer PP> ? PP |
| 2174 | : ExtractMatch<R, P> |
| 2175 | |
| 2176 | /** |
| 2177 | * Computes the remaining type when a pattern P is excluded from type R. |
| 2178 | * |
| 2179 | * **Details** |
| 2180 | * |
| 2181 | * This utility type determines what type remains after a `Match.not` pattern |
| 2182 | * excludes certain values. It's the complement of `WhenMatch`, calculating |
| 2183 | * what's left after removing the matched portion. |
| 2184 | * |
| 2185 | * **Example** (Computing unmatched types) |
| 2186 | * |
| 2187 | * ```ts import.meta.vitest |
| 2188 | * import type { Match } from "effect" |
| 2189 | * |
| 2190 | * // NotMatch computes what remains after exclusion |
| 2191 | * type NotString = Match.Types.NotMatch< |
| 2192 | * string | number | boolean, |
| 2193 | * typeof Match.string |
| 2194 | * > |
| 2195 | * // Result: number | boolean |
| 2196 | * |
| 2197 | * type NotSpecificValue = Match.Types.NotMatch<"a" | "b" | "c", "a"> |
| 2198 | * // Result: "b" | "c" |
| 2199 | * ``` |
| 2200 | * |
| 2201 | * @category utility types |
| 2202 | * @since 4.0.0 |
| 2203 | */ |
| 2204 | export type NotMatch<R, P> = Exclude<R, ExtractMatch<R, PForNotMatch<P>>> |
| 2205 | |
| 2206 | type PForNotMatch<P> = [ToInvertedRefinement<P>] extends [infer X] ? X |
| 2207 | : never |
| 2208 | |
| 2209 | /** |
| 2210 | * Resolves a pattern to its matched type for use in type computations. |
| 2211 | * |
| 2212 | * **Details** |
| 2213 | * |
| 2214 | * This utility type processes patterns (predicates, refinements, objects) |
| 2215 | * and resolves them to their corresponding matched types. It's used internally |
| 2216 | * to compute type transformations during pattern matching. |
| 2217 | * |
| 2218 | * **Example** (Resolving match patterns) |
| 2219 | * |
| 2220 | * ```ts import.meta.vitest |
| 2221 | * import type { Match } from "effect" |
| 2222 | * |
| 2223 | * // PForMatch resolves patterns to their matched types |
| 2224 | * type StringPattern = Match.Types.PForMatch<typeof Match.string> |
| 2225 | * // Result: string |
| 2226 | * |
| 2227 | * type ObjectPattern = Match.Types.PForMatch<{ name: string }> |
| 2228 | * // Result: { name: string } |
| 2229 | * ``` |
| 2230 | * |
| 2231 | * @category utility types |
| 2232 | * @since 4.0.0 |
| 2233 | */ |
| 2234 | export type PForMatch<P> = [ResolvePred<P>] extends [infer X] ? X |
| 2235 | : never |
| 2236 | |
| 2237 | /** |
| 2238 | * Computes the excluded type when a pattern P is used for exclusion. |
| 2239 | * |
| 2240 | * **Details** |
| 2241 | * |
| 2242 | * This utility type determines what should be excluded from a union type |
| 2243 | * when a pattern is used in filtering operations. It transforms patterns |
| 2244 | * into their exclusion-safe representations. |
| 2245 | * |
| 2246 | * **Example** (Computing excluded patterns) |
| 2247 | * |
| 2248 | * ```ts import.meta.vitest |
| 2249 | * import type { Match } from "effect" |
| 2250 | * |
| 2251 | * // PForExclude computes what to exclude from type operations |
| 2252 | * type ExcludeString = Match.Types.PForExclude<typeof Match.string> |
| 2253 | * // Used internally to filter out string types |
| 2254 | * |
| 2255 | * type ExcludeObject = Match.Types.PForExclude<{ type: "admin" }> |
| 2256 | * // Used internally to filter out admin objects |
| 2257 | * ``` |
| 2258 | * |
| 2259 | * @category utility types |
| 2260 | * @since 4.0.0 |
| 2261 | */ |
| 2262 | export type PForExclude<P> = [SafeRefinementR<ToSafeRefinement<P>>] extends [infer X] ? X |
| 2263 | : never |
| 2264 | |
| 2265 | // utilities |
| 2266 | type PredicateA<A> = Predicate.Predicate<A> | Predicate.Refinement<A, A> |
| 2267 | |
| 2268 | type SafeRefinementR<A> = A extends never ? never |
| 2269 | : A extends SafeRefinement<infer _, infer R> ? R |
| 2270 | : A extends Function ? A |
| 2271 | : A extends Record<string, any> ? { [K in keyof A]: SafeRefinementR<A[K]> } |
| 2272 | : A |
| 2273 | |
| 2274 | type ResolvePred<A, Input = any> = A extends never ? never |
| 2275 | : A extends SafeRefinement<infer _A, infer _R> ? _A |
| 2276 | : A extends Predicate.Refinement<Input, infer P> ? P |
| 2277 | : A extends Predicate.Predicate<infer P> ? P |
| 2278 | : A extends Record<string, any> ? { [K in keyof A]: ResolvePred<A[K]> } |
| 2279 | : A |
| 2280 | |
| 2281 | type ToSafeRefinement<A> = A extends never ? never |
| 2282 | : A extends Predicate.Refinement<any, infer P> ? SafeRefinement<P, P> |
| 2283 | : A extends Predicate.Predicate<infer P> ? SafeRefinement<P, never> |
| 2284 | : A extends SafeRefinement<any> ? A |
| 2285 | : A extends Record<string, any> ? { [K in keyof A]: ToSafeRefinement<A[K]> } |
| 2286 | : NonLiteralsTo<A, never> |
| 2287 | |
| 2288 | type ToInvertedRefinement<A> = A extends never ? never |
| 2289 | : A extends Predicate.Refinement<any, infer P> ? SafeRefinement<P> |
| 2290 | : A extends Predicate.Predicate<infer _P> ? SafeRefinement<never> |
| 2291 | : A extends SafeRefinement<infer _A, infer _R> ? SafeRefinement<_R> |
| 2292 | : A extends Record<string, any> ? { [K in keyof A]: ToInvertedRefinement<A[K]> } |
| 2293 | : NonLiteralsTo<A, never> |
| 2294 | |
| 2295 | type NonLiteralsTo<A, T> = [A] extends [string | number | boolean | bigint] ? [string] extends [A] ? T |
| 2296 | : [number] extends [A] ? T |
| 2297 | : [boolean] extends [A] ? T |
| 2298 | : [bigint] extends [A] ? T |
| 2299 | : A |
| 2300 | : A |
| 2301 | |
| 2302 | /** |
| 2303 | * Defines the structure for complex object and array patterns. |
| 2304 | * |
| 2305 | * **Details** |
| 2306 | * |
| 2307 | * This type represents patterns that can match against complex data structures |
| 2308 | * like objects and arrays. It supports nested pattern matching and partial |
| 2309 | * object matching, enabling sophisticated pattern compositions. |
| 2310 | * |
| 2311 | * **Example** (Describing complex object patterns) |
| 2312 | * |
| 2313 | * ```ts import.meta.vitest |
| 2314 | * import { Match } from "effect" |
| 2315 | * |
| 2316 | * // PatternBase enables complex object patterns |
| 2317 | * type UserPattern = Match.Types.PatternBase<{ |
| 2318 | * name: string |
| 2319 | * age: number |
| 2320 | * role: "admin" | "user" |
| 2321 | * }> |
| 2322 | * // Allows: { name?: string | Predicate, age?: number | Predicate, ... } |
| 2323 | * |
| 2324 | * // Example usage: |
| 2325 | * const result = Match.value({ name: "Alice", age: 30, role: "admin" as const }).pipe( |
| 2326 | * Match.when( |
| 2327 | * { age: (n: number) => n >= 18, role: "admin" }, |
| 2328 | * (user: { name: string; age: number; role: "admin" }) => |
| 2329 | * `Admin: ${user.name}` |
| 2330 | * ), |
| 2331 | * Match.orElse(() => "Not an adult admin") |
| 2332 | * ) |
| 2333 | * result // => "Admin: Alice" |
| 2334 | * ``` |
| 2335 | * |
| 2336 | * @category utility types |
| 2337 | * @since 4.0.0 |
| 2338 | */ |
| 2339 | export type PatternBase<A> = A extends ReadonlyArray<infer _T> ? ReadonlyArray<any> | PatternPrimitive<A> |
| 2340 | : A extends Record<string, any> ? Partial< |
| 2341 | { [K in keyof A]: PatternPrimitive<A[K] & {}> | PatternBase<A[K] & {}> } |
| 2342 | > |
| 2343 | : never |
| 2344 | |
| 2345 | /** |
| 2346 | * Defines primitive patterns that can match simple values. |
| 2347 | * |
| 2348 | * **Details** |
| 2349 | * |
| 2350 | * This type represents the building blocks of pattern matching: predicates, |
| 2351 | * literal values, and safe refinements. These are the atomic patterns that |
| 2352 | * can be composed into more complex matching logic. |
| 2353 | * |
| 2354 | * @category utility types |
| 2355 | * @since 4.0.0 |
| 2356 | */ |
| 2357 | export type PatternPrimitive<A> = PredicateA<A> | A | SafeRefinement<any> |
| 2358 | |
| 2359 | /** |
| 2360 | * Represents a filter that excludes specific types from a union. |
| 2361 | * |
| 2362 | * **Details** |
| 2363 | * |
| 2364 | * `Without` is used internally to track which types should be excluded |
| 2365 | * from consideration during pattern matching. It helps implement the |
| 2366 | * type-level logic for `Match.not` and other exclusion operations. |
| 2367 | * |
| 2368 | * **Example** (Tracking excluded types) |
| 2369 | * |
| 2370 | * ```ts import.meta.vitest |
| 2371 | * import { Match } from "effect" |
| 2372 | * |
| 2373 | * // Without is used internally when you write: |
| 2374 | * const match = Match.type<string | number | boolean>().pipe( |
| 2375 | * Match.not(Match.string, (value) => `not string: ${value}`), |
| 2376 | * // At this point, type system uses Without<string> to track exclusion |
| 2377 | * Match.orElse(() => "was a string") |
| 2378 | * ) |
| 2379 | * match(42) // => "not string: 42" |
| 2380 | * ``` |
| 2381 | * |
| 2382 | * @category utility types |
| 2383 | * @since 4.0.0 |
| 2384 | */ |
| 2385 | export interface Without<out X> { |
| 2386 | readonly _tag: "Without" |
| 2387 | readonly _X: X |
| 2388 | } |
| 2389 | |
| 2390 | /** |
| 2391 | * Represents a filter that includes only specific types from a union. |
| 2392 | * |
| 2393 | * **Details** |
| 2394 | * |
| 2395 | * `Only` is used internally to track which types should be exclusively |
| 2396 | * considered during pattern matching. It helps implement the type-level |
| 2397 | * logic for positive matches and type narrowing. |
| 2398 | * |
| 2399 | * **Example** (Tracking included types) |
| 2400 | * |
| 2401 | * ```ts import.meta.vitest |
| 2402 | * import { Match } from "effect" |
| 2403 | * |
| 2404 | * // Only is used internally when you write: |
| 2405 | * const match = Match.type<string | number | boolean>().pipe( |
| 2406 | * Match.when(Match.string, (s) => `string: ${s}`), |
| 2407 | * // At this point, type system uses Only<string> for the match |
| 2408 | * Match.orElse((value) => `not string: ${value}`) |
| 2409 | * ) |
| 2410 | * match("ok") // => "string: ok" |
| 2411 | * ``` |
| 2412 | * |
| 2413 | * @category utility types |
| 2414 | * @since 4.0.0 |
| 2415 | */ |
| 2416 | export interface Only<out X> { |
| 2417 | readonly _tag: "Only" |
| 2418 | readonly _X: X |
| 2419 | } |
| 2420 | |
| 2421 | /** |
| 2422 | * Adds a type to the exclusion filter, expanding what should be filtered out. |
| 2423 | * |
| 2424 | * **Details** |
| 2425 | * |
| 2426 | * This utility type manages the accumulation of excluded types during |
| 2427 | * pattern matching. When multiple exclusions are applied, it combines |
| 2428 | * them into a single filter representation. |
| 2429 | * |
| 2430 | * **Example** (Accumulating excluded types) |
| 2431 | * |
| 2432 | * ```ts import.meta.vitest |
| 2433 | * import { Match } from "effect" |
| 2434 | * |
| 2435 | * // AddWithout is used when combining multiple exclusions: |
| 2436 | * const match = Match.type<string | number | boolean | null>().pipe( |
| 2437 | * Match.not(Match.string, () => "not string"), |
| 2438 | * Match.not(Match.number, () => "not number"), |
| 2439 | * // Type system uses AddWithout to combine exclusions |
| 2440 | * Match.orElse(() => "was string or number") |
| 2441 | * ) |
| 2442 | * match(true) // => "not string" |
| 2443 | * ``` |
| 2444 | * |
| 2445 | * @category utility types |
| 2446 | * @since 4.0.0 |
| 2447 | */ |
| 2448 | export type AddWithout<A, X> = [A] extends [Without<infer WX>] ? Without<X | WX> |
| 2449 | : [A] extends [Only<infer OX>] ? Only<Exclude<OX, X>> |
| 2450 | : never |
| 2451 | |
| 2452 | /** |
| 2453 | * Adds a type to the inclusion filter, refining what should be included. |
| 2454 | * |
| 2455 | * **Details** |
| 2456 | * |
| 2457 | * This utility type manages the refinement of included types during |
| 2458 | * pattern matching. It ensures that only the most specific type |
| 2459 | * constraints are maintained when multiple positive matches are applied. |
| 2460 | * |
| 2461 | * **Example** (Refining included types) |
| 2462 | * |
| 2463 | * ```ts import.meta.vitest |
| 2464 | * import { Match } from "effect" |
| 2465 | * |
| 2466 | * // AddOnly is used when refining positive matches: |
| 2467 | * const match = Match.type<{ type: "user" | "admin"; name: string }>().pipe( |
| 2468 | * Match.when({ type: "admin" }, (admin) => admin.name), |
| 2469 | * // Type system uses AddOnly to refine the constraint |
| 2470 | * Match.orElse(() => "not admin") |
| 2471 | * ) |
| 2472 | * match({ type: "admin", name: "Alice" }) // => "Alice" |
| 2473 | * ``` |
| 2474 | * |
| 2475 | * @category utility types |
| 2476 | * @since 4.0.0 |
| 2477 | */ |
| 2478 | export type AddOnly<A, X> = [A] extends [Without<infer WX>] ? [X] extends [WX] ? never |
| 2479 | : Only<X> |
| 2480 | : [A] extends [Only<infer OX>] ? [X] extends [OX] ? Only<X> |
| 2481 | : never |
| 2482 | : never |
| 2483 | |
| 2484 | /** |
| 2485 | * Applies accumulated filters to an input type, producing the final narrowed type. |
| 2486 | * |
| 2487 | * **Details** |
| 2488 | * |
| 2489 | * This utility type takes the collected inclusion/exclusion filters and |
| 2490 | * applies them to the input type to compute the final narrowed result. |
| 2491 | * It's the culmination of the type-level filtering process. |
| 2492 | * |
| 2493 | * **Example** (Applying accumulated filters) |
| 2494 | * |
| 2495 | * ```ts import.meta.vitest |
| 2496 | * import type { Match } from "effect" |
| 2497 | * |
| 2498 | * // ApplyFilters computes the final narrowed type: |
| 2499 | * type Result = Match.Types.ApplyFilters< |
| 2500 | * string | number | boolean, |
| 2501 | * Match.Types.Only<string> |
| 2502 | * > |
| 2503 | * // Result: string |
| 2504 | * |
| 2505 | * type ExclusionResult = Match.Types.ApplyFilters< |
| 2506 | * string | number | boolean, |
| 2507 | * Match.Types.Without<string> |
| 2508 | * > |
| 2509 | * // Result: number | boolean |
| 2510 | * ``` |
| 2511 | * |
| 2512 | * @category utility types |
| 2513 | * @since 4.0.0 |
| 2514 | */ |
| 2515 | export type ApplyFilters<I, A> = A extends Only<infer X> ? X |
| 2516 | : A extends Without<infer X> ? Exclude<I, X> |
| 2517 | : never |
| 2518 | |
| 2519 | /** |
| 2520 | * Extracts tag values from a discriminated union based on a discriminant field. |
| 2521 | * |
| 2522 | * **Details** |
| 2523 | * |
| 2524 | * This utility type extracts the possible values of a discriminant field |
| 2525 | * from a union type. It's used internally to implement tag-based pattern |
| 2526 | * matching for discriminated unions. |
| 2527 | * |
| 2528 | * **Example** (Extracting discriminator tags) |
| 2529 | * |
| 2530 | * ```ts import.meta.vitest |
| 2531 | * import type { Match } from "effect" |
| 2532 | * |
| 2533 | * type Events = |
| 2534 | * | { _tag: "click"; x: number; y: number } |
| 2535 | * | { _tag: "keypress"; key: string } |
| 2536 | * | { _tag: "scroll"; delta: number } |
| 2537 | * |
| 2538 | * type EventTags = Match.Types.Tags<"_tag", Events> |
| 2539 | * // Result: "click" | "keypress" | "scroll" |
| 2540 | * |
| 2541 | * type CustomTags = Match.Types.Tags< |
| 2542 | * "type", |
| 2543 | * | { type: "user"; name: string } |
| 2544 | * | { type: "admin"; permissions: Array<string> } |
| 2545 | * > |
| 2546 | * // Result: "user" | "admin" |
| 2547 | * ``` |
| 2548 | * |
| 2549 | * @category utility types |
| 2550 | * @since 4.0.0 |
| 2551 | */ |
| 2552 | export type Tags<D extends string, P> = P extends Record<D, infer X> ? X : never |
| 2553 | |
| 2554 | /** |
| 2555 | * Converts an array type to an intersection of its element types. |
| 2556 | * |
| 2557 | * **Details** |
| 2558 | * |
| 2559 | * This utility type takes an array of types and converts them into a single |
| 2560 | * intersection type. It's used internally when multiple patterns need to |
| 2561 | * be satisfied simultaneously (like in `Match.whenAnd`). |
| 2562 | * |
| 2563 | * **Example** (Converting arrays to intersections) |
| 2564 | * |
| 2565 | * ```ts import.meta.vitest |
| 2566 | * import type { Match } from "effect" |
| 2567 | * |
| 2568 | * type Combined = Match.Types.ArrayToIntersection<[ |
| 2569 | * { name: string }, |
| 2570 | * { age: number }, |
| 2571 | * { active: boolean } |
| 2572 | * ]> |
| 2573 | * // Result: { name: string } & { age: number } & { active: boolean } |
| 2574 | * // = { name: string; age: number; active: boolean } |
| 2575 | * |
| 2576 | * // This type utility enables complex type intersections |
| 2577 | * // Complex type operations are handled by this utility type |
| 2578 | * // for advanced pattern matching scenarios |
| 2579 | * ``` |
| 2580 | * |
| 2581 | * @category utility types |
| 2582 | * @since 4.0.0 |
| 2583 | */ |
| 2584 | export type ArrayToIntersection<A extends ReadonlyArray<any>> = T.UnionToIntersection< |
| 2585 | A[number] |
| 2586 | > |
| 2587 | |
| 2588 | /** |
| 2589 | * Extracts and narrows the matched type from an input type given a pattern. |
| 2590 | * |
| 2591 | * **Details** |
| 2592 | * |
| 2593 | * This is the core type utility that performs the actual type extraction |
| 2594 | * and narrowing logic. It handles the complex type-level computation that |
| 2595 | * determines what type results from applying a pattern to an input type. |
| 2596 | * |
| 2597 | * **Example** (Extracting matched types) |
| 2598 | * |
| 2599 | * ```ts import.meta.vitest |
| 2600 | * import { Match } from "effect" |
| 2601 | * |
| 2602 | * type StringExtract = Match.Types.ExtractMatch< |
| 2603 | * string | number | boolean, |
| 2604 | * typeof Match.string |
| 2605 | * > |
| 2606 | * // Result: string |
| 2607 | * |
| 2608 | * type ObjectExtract = Match.Types.ExtractMatch< |
| 2609 | * { type: "user"; name: string } | { type: "admin"; role: string }, |
| 2610 | * { type: "user" } |
| 2611 | * > |
| 2612 | * // Result: { type: "user"; name: string } |
| 2613 | * |
| 2614 | * // This powers the type narrowing in: |
| 2615 | * Match.when(Match.string, (s) => s.toUpperCase()) |
| 2616 | * // ^^^ s is correctly typed as string |
| 2617 | * ``` |
| 2618 | * |
| 2619 | * @category utility types |
| 2620 | * @since 4.0.0 |
| 2621 | */ |
| 2622 | export type ExtractMatch<I, P> = [ExtractAndNarrow<I, P>] extends [infer EI] ? EI |
| 2623 | : never |
| 2624 | |
| 2625 | type Replace<A, B> = A extends Function ? A |
| 2626 | : A extends Record<string | number, any> ? { [K in keyof A]: K extends keyof B ? Replace<A[K], B[K]> : A[K] } |
| 2627 | : [B] extends [A] ? B |
| 2628 | : A |
| 2629 | |
| 2630 | type MaybeReplace<I, P> = [P] extends [I] ? P |
| 2631 | : [I] extends [P] ? Replace<I, P> |
| 2632 | : Fail |
| 2633 | |
| 2634 | type BuiltInObjects = |
| 2635 | | Function |
| 2636 | | Date |
| 2637 | | RegExp |
| 2638 | | Generator |
| 2639 | | { readonly [Symbol.toStringTag]: string } |
| 2640 | |
| 2641 | type IsPlainObject<T> = T extends BuiltInObjects ? false |
| 2642 | : T extends Record<string, any> ? true |
| 2643 | : false |
| 2644 | |
| 2645 | type Simplify<A> = { [K in keyof A]: A[K] } & {} |
| 2646 | |
| 2647 | type ExtractAndNarrow<Input, P> = P extends Predicate.Refinement<infer _In, infer _Out> ? |
| 2648 | _Out extends Input ? Extract<_Out, Input> |
| 2649 | : Extract<Input, _Out> : |
| 2650 | P extends SafeRefinement<infer _In, infer _R> ? [0] extends [1 & _R] ? Input |
| 2651 | : _In extends Input ? Extract<_In, Input> |
| 2652 | : Extract<Input, _In> |
| 2653 | : P extends Predicate.Predicate<infer _In> ? Extract<Input, _In> |
| 2654 | : Input extends infer I ? Exclude< |
| 2655 | I extends ReadonlyArray<any> ? P extends ReadonlyArray<any> ? { |
| 2656 | readonly [K in keyof I]: K extends keyof P ? ExtractAndNarrow<I[K], P[K]> |
| 2657 | : I[K] |
| 2658 | } extends infer R ? Fail extends R[keyof R] ? never |
| 2659 | : R |
| 2660 | : never |
| 2661 | : never |
| 2662 | : IsPlainObject<I> extends true ? string extends keyof I ? I extends P ? I |
| 2663 | : never |
| 2664 | : symbol extends keyof I ? I extends P ? I |
| 2665 | : never |
| 2666 | : Simplify< |
| 2667 | & { [RK in Extract<keyof I, keyof P>]-?: ExtractAndNarrow<I[RK], P[RK]> } |
| 2668 | & Omit<I, keyof P> |
| 2669 | > extends infer R ? keyof P extends NonFailKeys<R> ? R |
| 2670 | : never |
| 2671 | : never |
| 2672 | : MaybeReplace<I, P> extends infer R ? [I] extends [R] ? I |
| 2673 | : R |
| 2674 | : never, |
| 2675 | Fail |
| 2676 | > : |
| 2677 | never |
| 2678 | |
| 2679 | type NonFailKeys<A> = keyof A & {} extends infer K ? K extends keyof A ? A[K] extends Fail ? never : K |
| 2680 | : never : |
| 2681 | never |
| 2682 | } |