lue-bird/elm-linear-direction 3.0.0

linear direction

Q: Can direction be better expressed than in

foldr, foldl: does foldr mean fold right? A quite unclear name
no Array.getr/l, setr/l but foldr, 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

A: Use the direction as an argument:

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

[ 'l', 'i', 'v', 'e' ]
    |> List.Linear.foldFrom "" FirstToLast String.cons
--> "evil"

[ 'l', 'i', 'v', 'e' ]
    |> List.Linear.foldFrom "" LastToFirst String.cons
--> "live"

last : Array element -> Maybe element
last =
    Array.Linear.at 0 LastToFirst

→ a less cluttered API, e.g.
- foldFrom instead of foldr, foldl
- toChunksOf instead of chunksFromLeft/-Right

→ deal with both directions at once

import LinearDirection exposing (LinearDirection)
import Array exposing (Array)
import Array.Linear

alterAt :
    Int -> LinearDirection -> (a -> a) -> Array a -> Array a
alterAt index direction alter =
    \array ->
        array
            |> Array.Linear.replaceAt index direction
                (array
                    |> Array.Linear.at index direction
                    |> alter
                )

lue-bird/elm-linear-direction/3.0.0

linear direction

this is being used in

suggestions?

Modules