<https://github.com/arrow-kt/arrow/pull/2540>

# arrow-contributors

[pakoito]

https://github.com/arrow-kt/arrow/pull/2540

[kioba]

we are planning to do a different bind solution on extra requirements in our android state management. We wanted to bring in Async work into our scope and also provide an environment for the binding.

something similar:

public suspend fun <E : Environment, ER, R> EitherScope<E, ER>.bind(
    f: suspend E.() -> Either<R, ER>,
) : R

public suspend fun <E : Environment, ER, R> EitherScope<E, ER>.bindAsync(
    f: suspend E.() -> Either<R, ER>,
) : Deferred<R>

instead of binding on the Either type we bind on the scope and the bind argument return value will be evaluated.

usage:

either {
    val a = bind { this.myNetworkCall() }
    val b = bindAsync { this.myNetworkCall2() }
    b.await()
}

[kioba]

we baked in our Error type but could effectively provide a mapper for as the first argument.

bind({ it.message }) { myCall() }

[pakoito]

Isn't that Either.catch? with .bind

[kioba]

yeah it is 👍

val env = getEnvironment()
val a = Either.catch { env.networkCall() }.bind()

our usecase requires the environment so we could add it in scope 🙂

[kioba]

having async also adds quite a lot of nesting so we aimed to reduce the required setup

coroutineScope {
    val env = getEnvironment()
    val a = async { Either.catch { env.networkCall() }.bind() }
}