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Update "Creating Results" section in README

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Michael Bull 2019-08-24 00:31:23 +01:00
parent 31808eb99c
commit ed430c4eca
1 changed files with 14 additions and 14 deletions
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README.md
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@ -36,17 +36,6 @@ using the `Result` type in other languages:
### Creating Results
To begin incorporating the `Result` type into an existing codebase, you can
wrap functions that may fail (i.e. throw an `Exception`) with
[`Result.of`][result-of]. This will execute the block of code and `catch` any
`Exception`, returning a `Result<T, Exception>`.
```kotlin
val result: Result<Customer, Exception> = Result.of {
customerDb.findById(id = 50) // could throw SQLException or similar
}
```
The idiomatic approach to modelling operations that may fail in Railway
Oriented Programming is to avoid throwing an exception and instead make the
return type of your function a `Result`.
@ -61,6 +50,17 @@ fun checkPrivileges(user: User, command: Command): Result<Command, CommandError>
}
```
To incorporate the `Result` type into an existing codebase that throws
exceptions, you can wrap functions that may `throw` with
[`runCatching`][result-runCatching]. This will execute the block of code and
`catch` any `Throwable`, returning a `Result<T, Throwable>`.
```kotlin
val result: Result<Customer, Throwable> = runCatching {
customerDb.findById(id = 50) // could throw SQLException or similar
}
```
Nullable types, such as the `find` method in the example below, can be
converted to a `Result` using the `toResultOr` extension function.
@ -201,9 +201,9 @@ This project is available under the terms of the ISC license. See the
[`LICENSE`](LICENSE) file for the copyright information and licensing terms.
[result]: https://github.com/michaelbull/kotlin-result/blob/master/src/main/kotlin/com/github/michaelbull/result/Result.kt#L10
[result-ok]: https://github.com/michaelbull/kotlin-result/blob/master/src/main/kotlin/com/github/michaelbull/result/Result.kt#L30
[result-err]: https://github.com/michaelbull/kotlin-result/blob/master/src/main/kotlin/com/github/michaelbull/result/Result.kt#L35
[result-of]: https://github.com/michaelbull/kotlin-result/blob/master/src/main/kotlin/com/github/michaelbull/result/Result.kt#L17
[result-ok]: https://github.com/michaelbull/kotlin-result/blob/master/src/main/kotlin/com/github/michaelbull/result/Result.kt#L31
[result-err]: https://github.com/michaelbull/kotlin-result/blob/master/src/main/kotlin/com/github/michaelbull/result/Result.kt#L36
[result-runCatching]: https://github.com/michaelbull/kotlin-result/blob/master/src/main/kotlin/com/github/michaelbull/result/Factory.kt#L11
[swalschin-rop]: https://fsharpforfunandprofit.com/rop/
[wiki]: https://github.com/michaelbull/kotlin-result/wiki
[unit-tests]: https://github.com/michaelbull/kotlin-result/tree/master/src/test/kotlin/com/github/michaelbull/result