81 lines
3.4 KiB
Markdown
81 lines
3.4 KiB
Markdown
# kotlin-result
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[](https://jitpack.io/#michaelbull/kotlin-result) [](https://travis-ci.org/michaelbull/kotlin-result) [](https://github.com/michaelbull/kotlin-result/blob/master/LICENSE)
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[`Result<V, E>`][result] is a monad for modelling success ([`Ok`][result-ok]) or
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failure ([`Err`][result-err]) operations.
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## Inspiration
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Inspiration for this library has been drawn from other languages in which the
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Result monad is present, including:
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- [Elm](http://package.elm-lang.org/packages/elm-lang/core/latest/Result)
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- [Haskell](https://hackage.haskell.org/package/base-4.10.0.0/docs/Data-Either.html)
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- [Rust](https://doc.rust-lang.org/std/result/)
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It also iterates on other Result libraries written in Kotlin, namely:
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- [danneu/kotlin-result](https://github.com/danneu/kotlin-result)
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- [kittinunf/Result](https://github.com/kittinunf/Result)
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- [npryce/result4k](https://github.com/npryce/result4k)
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Improvements on the existing solutions include:
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- Feature parity with Result types from other languages including Elm, Haskell,
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& Rust
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- Lax constraints on `value`/`error` nullability
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- Lax constraints on the `error` type's inheritance (does not inherit from
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`Exception`)
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- Top level `Ok` and `Error` classes avoids qualifying usages with
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`Result.Ok`/`Result.Error` respectively
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- Higher-order functions marked with the `inline` keyword for reduced runtime
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overhead
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- Extension functions on `Iterable` & `List` for folding, combining, partitioning
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- Consistent naming with existing Result libraries from other languages (e.g.
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`map`, `mapError`, `mapBoth`, `mapEither`, `and`, `andThen`, `or`, `orElse`,
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`unwrap`)
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- Extensive test suite with over 50 unit tests covering every library method
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## Installation
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```groovy
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repositories {
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maven { url "https://jitpack.io" }
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}
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dependencies {
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compile 'com.github.michaelbull:kotlin-result:1.1.0'
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}
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```
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## Getting Started
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The [unit tests][unit-tests] are a good source of examples for using the library
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as they cover every available method.
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Mappings from common Result libraries are available on the [wiki][wiki]:
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- [Elm][wiki-elm]
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- [Haskell][wiki-haskell]
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- [Rust][wiki-rust]
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## Contributing
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Bug reports and pull requests are welcome on [GitHub][github].
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## License
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This project is available under the terms of the ISC license. See the
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[`LICENSE`](LICENSE) file for the copyright information and licensing terms.
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[result]: https://github.com/michaelbull/kotlin-result/blob/master/src/main/kotlin/com/github/michaelbull/result/Result.kt#L10
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[result-ok]: https://github.com/michaelbull/kotlin-result/blob/master/src/main/kotlin/com/github/michaelbull/result/Result.kt#L27
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[result-err]: https://github.com/michaelbull/kotlin-result/blob/master/src/main/kotlin/com/github/michaelbull/result/Result.kt#L28
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[unit-tests]: https://github.com/michaelbull/kotlin-result/tree/master/src/test/kotlin/com/github/michaelbull/result
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[wiki]: https://github.com/michaelbull/kotlin-result/wiki
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[wiki-elm]: https://github.com/michaelbull/kotlin-result/wiki/Elm
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[wiki-haskell]: https://github.com/michaelbull/kotlin-result/wiki/Haskell
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[wiki-rust]: https://github.com/michaelbull/kotlin-result/wiki/Rust
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[github]: https://github.com/michaelbull/kotlin-result
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