How to format nested continuations nicely

@Reactormonk provided a helpful link, but Elm

not Haskell

. Otherwise, we could have used the Maybe monad

syntactic sugar provided do-notation

. Something like:

do
  (parentGroup, parentTail) <- popStack groupTail
  updatedParent <- addChild currentGroup sibling
  case sibling of
    SingleExercise _ ->
      workHelp siblingIndent (updatedParent : parentTail)
    WorkGroup _ _ ->
      workHelp siblingIndent (sibling : (updatedParent : parentTail))

      

        
        
        
      

    

But in Elm

I would include the move logic in separate functions:

let
    workHelpToSibling sibling ( parentTail, updatedParent ) =
        case sibling of
            SingleExercise ->
                workHelp siblingIndent (updatedParent :: parentTail)

            WorkGroup ->
                workHelp siblingIndent (sibling :: (updatedParent :: parentTail))

    addChildTo currentGroup sibling ( parentGroup, parentTail ) =
        addChild currentGroup sibling
            |> Maybe.map (\updatedParent -> ( parentTail, updatedParent ))
in
    popStack groupTail
        |> andThen (addChildTo currentGroup sibling)
        |> andThen (workHelpToSibling sibling)

      

        
        
        
      

    

Since you have currentGroup

and sibling

are available at a higher level, this code can be refactored to reduce the arity of functions (and not only that).

I just wanted to point out the idea of ​​minimizing the padding level, which really looks like backwards hell.