how do you filter and replace a given result with ...

# arrow

[Fred Friis]

how do you filter and replace a given result with error in a Kotlin Result and Arrow Either?

eg given the types

Result<Response> or
Either<Throwable, Response>

if the response in the success case/on the right has response.isSuccessful is false, I want to turn that into a failed result/throwable on the left

[dave08]

I think you can bind() a result in an either scope?

[Laurent Thiebaud]

what about .map() functions in Arrow ?

[raulraja]

scratch.kt

scratch.kt

[raulraja]

You could use bind or flatMap like in the snippet above.

[raulraja]

Or use the Raise DSL to create your own operations for the either block.

[Alejandro Serrano.Mena]

the simples way would be to do:

fun <A> Either<Throwable, A>.toResult() = Result<A> = either { this.bind() }

fun <A> Result<A>.toEither(): Either<Throwable, A> = result { this.bind() }

the general pattern is that the outer block (`either`/`result`) tells you the result type, and bind() "injects" an error into the context

[raulraja]

raise.kt.cpp

raise.kt.cpp

[Fred Friis]

what about filterOrElse and filterOrOther? they look like they should do roughly the same thing?

https://github.com/arrow-kt/arrow/issues/1179