Example usage:

module RemoteData.Extra exposing (andCollect)


import AndCollect
import RemoteData exposing (RemoteData)


andCollect :
    (a -> RemoteData e b)
    -> RemoteData e a
    -> RemoteData e ( a, b )
andCollect callback oldRemoteData =
    AndCollect.custom
        RemoteData.andThen
        RemoteData.map
        callback
        oldRemoteData

You may then use RemoteData.Extra.andCollect by turning code such as this...

import RemoteData


getRemoteAnswer : RemoteData error Int
getRemoteAnswer =
    getA
        |> RemoteData.andThen
            (\a ->
                getB a
                    |> RemoteData.andThen
                        (\b ->
                            getC a b
                                |> remoteData.andThen
                                    (\c ->
                                        solve a b c
                                    )
                        )
            )

...into this:

import RemoteData
import RemoteData.Extra as RemoteData


getRemoteAnswer : RemoteData error Int
getRemoteAnswer =
    getA
        |> RemoteData.andCollect getB
        |> RemoteData.andCollect (\( a, b ) -> getC a b)
        |> RemoteData.andThen (\( ( a, b ), c ) -> solve a b c)

(The LSP's inferred signature was used. Feedback or experimentation should be gathered to ensure the lack of higher-kinded types isn't causing any weird gotchas.)