hello, everyone is there a shorter/cleaner way to ...

# arrow

[dephinera]

hello, everyone
is there a shorter/cleaner way to do the following

either1.fold(
        ifLeft = { it.left() },
        ifRight = { r1 ->
            either2.fold(
                    ifLeft = { it.left() },
                    ifRight = { r2 -> mapper(r1, r2).right() },
            )
        }
)

The left type of both eithers is the same. I want to call mapper() if both of eithers are Right. If one of them is Left, mapper won't be called. The result type is Either<SameLeftType, ReturnedTypeFromMapper>.

[than_]

Either.mapN(e1, e2){ a, b -> mapper(a,b) }

[dephinera]

thanks @than_! Which version is this included in? I'm using Arrow-Core 0.11 and it's not there

[than_]

sorry. this moved in 0.12.0-SNAPSHOT.. I believe it's just

mapN(e1, e2){ a, b -> mapper(a,b) }

in 0.11.0

[dephinera]

ah, right! Thanks

[than_]

import arrow.core.extensions.either.apply.mapN

I believe it can be found here

[dephinera]

However this doesn't look like what I need. It's for nullable types, not Either or am I wrong?

[than_]

wrong import 🙂

[dephinera]

🙈 thanks

[than_]

there is A LOT of mapN functions. I believe there is one for every monad (and nullables), for every arity up to like 10 😄 Just search a bit

[dephinera]

Yeah, I guess they moved it to Either. for a reason 😄