tmu
1ad19ba308
State the end-user limits once, in README § Caveats: a member colliding with its stringification, the unsupported symbol/bigint, and NaN/-0. Drop the duplicated known-issue prose from development/library.md and the source comment; link to the README instead.
48 lines
1.9 KiB
Markdown
48 lines
1.9 KiB
Markdown
# tiny-pattern-ts
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Pattern matching for TypeScript/ESM environments (F#-style, not regex).
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## Description
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`tiny-pattern-ts` brings F#-style pattern matching to TypeScript. Patterns are
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ordinary objects whose `matches` method is a TypeScript type guard, so narrowing
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composes the way any other guard does. It is deliberately not a regex engine and
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not a macro: there is no transpiler and no DSL to learn, and the type-level
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contract is the feature — see [development/library.md](./development/library.md)
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for the design decisions and [Caveats](#caveats) for the limits.
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## Requirements
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- **Node.js >= 26** (`engines` field; pinned via `.node-version`).
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- **TypeScript >= 5.0** to consume the published declarations. The emitted `.d.ts`
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use `const` type parameters (TS 5.0) and keep their relative `.ts` specifiers;
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both resolve on TS >= 5.0 in `node10` / `node16` / `nodenext` / `bundler`.
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- The package is **ESM-only** (no CommonJS shim).
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## API
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Yet to be implemented
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## Caveats
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- **A value and its stringification collide.** Object keys stringify, so a
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universe that mixes a member with the string it stringifies to — `1 | "1"`,
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`true | "true"`, `null | "null"` — collapses to a single handler key and both
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members are routed to it. Use one form or the other.
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- **`symbol` and `bigint` are not supported.** A `symbol` brand is a
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compile-time phantom with nothing to match at runtime, and a `bigint` is not a
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valid property key; neither satisfies the matcher's universe constraint.
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- **`NaN` and `-0` cannot be matched specifically.** They have no literal type,
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so both stay part of `number`.
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## License
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MIT © 2025 tmu. See [LICENSE](./LICENSE).
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## Contributing
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Contributions are documented in [CONTRIBUTING.md](./CONTRIBUTING.md); the
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reasons behind the project's decisions, rejected alternatives, and known issues
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live in [development/](./development/README.md). AI coding agents start at
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[AGENTS.md](./AGENTS.md).
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