lue-bird/elm-linear-direction/2.1.0

elm-linear-direction

I think direction can be better expressed than in

• foldr and foldl: does foldr mean fold right? A quite unclear name
• no getr/l, setr/l, but foldr and foldl?
• negative indices
  • Array.slice 0 -1 is handy! But you can't do slice 2 -0
  • Many operations support negative indices, but others don't
  • not explicit → can have unintended side-effects

This package's simple goal is allowing you to use the direction as an argument.

import LinearDirection exposing (LinearDirection(..))
import List.LinearDirection as List
import LinearDirection.Array as Array

[ "m", "l", "e" ]
    |> List.fold LastToFirst (++) ""
--> "elm"

last : Array a -> Maybe a
last =
    Array.at 0 LastToFirst

• → a less cluttered API (e.g. one fold instead of foldr foldl or group instead of chunksFromLeft/Right)

• → deal with both directions at once

  import LinearDirection exposing (LinearDirection)
  import LinearDirection.Array as Array
  
  updateAt :
      Int -> LinearDirection -> (a -> a) -> Array a -> Array a
  updateAt index direction alter =
      Array.replaceAt index direction
          (alter (Array.at index direction))

• → direction is always explicit