https://github.com/lue-bird/elm-emptiness-typed

one type for emptiable and safe non-empty
https://github.com/lue-bird/elm-emptiness-typed

elm focus non-empty pivot scroll select-list type-safety ziplist

Last synced: 4 months ago
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one type for emptiable and safe non-empty

• Host: GitHub
• URL: https://github.com/lue-bird/elm-emptiness-typed
• Owner: lue-bird
• License: mit
• Fork: true (zwilias/elm-holey-zipper)
• Created: 2021-11-14T11:03:20.000Z (about 3 years ago)
• Default Branch: master
• Last Pushed: 2023-05-23T23:45:34.000Z (over 1 year ago)
• Last Synced: 2023-08-08T20:39:34.994Z (over 1 year ago)
• Topics: elm, focus, non-empty, pivot, scroll, select-list, type-safety, ziplist
• Language: Elm
• Homepage: https://package.elm-lang.org/packages/lue-bird/elm-emptiness-typed/latest/
• Size: 3.12 MB
• Stars: 0
• Watchers: 0
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Changelog: changes.md
  • Contributing: contributing.md
  • License: LICENSE

Awesome Lists containing this project

README

        
> one type for emptiable and safe non-empty

# [emptiness typed](https://package.elm-lang.org/packages/lue-bird/elm-emptiness-typed/latest/)

**_🧩 Read about [allowable state](https://package.elm-lang.org/packages/lue-bird/elm-allowable-state/latest/) first_**

## [📦 `Emptiable`](Emptiable) `.....  Never |` [`Possibly`](https://dark.elm.dmy.fr/packages/lue-bird/elm-allowable-state/latest/Possibly)

A `Maybe` value that can be made non-empty depending on what we know – an "emptiable-able" value

```elm

import Emptiable exposing (Emptiable, filled, fill)

type alias TextFilled =

    { first : Char, afterFirst : String }

first : Emptiable TextFilled Never -> Char

first =

    fill >> .first

maybeFirst :

    Emptiable TextFilled possiblyOrNever

    -> Emptiable Char possiblyOrNever

maybeFirst =

    Emptiable.map (filled >> first)

```

## [📚 `Stack`](Stack)

Handle lists that are

[`Possibly`](https://dark.elm.dmy.fr/packages/lue-bird/elm-allowable-state/latest/Possibly)

or `Never` [`Emptiable`](Emptiable#Emptiable)

in one go

`Emptiable ... Never` allows safe `Maybe`-free

[`top`](Stack#top), [`removeTop`](Stack#removeTop),

[`fold`](Stack#fold) (for finding the maximum etc.; some call it "fold1"), ...

That's more useful than you might think.

```elm

import Linear exposing (Direction(..))

import Emptiable exposing (Emptiable)

import Stack exposing (Stacked)

Emptiable.empty

    --: Emptiable (Stacked element_) Possibly

    |> Stack.onTopLay 0

    --: Emptiable (Stacked number_) never_

    |> Stack.attach Down (Stack.topBelow 1 [ 2, 3 ])

    --: Emptiable (Stacked number_) never_

    |> Stack.toTopBelow

--> ( 1, [ 2, 3, 0 ] )

```

## where `emptiness-typed` is already being used

- [🗃️ `elm-keysSet`](https://dark.elm.dmy.fr/packages/lue-bird/elm-keysset/latest/)

- [📜 `elm-scroll`](https://dark.elm.dmy.fr/packages/lue-bird/elm-scroll/latest/)

- [🚥 `typesafe-array`](https://dark.elm.dmy.fr/packages/lue-bird/elm-typesafe-array/latest/)

## suggestions?

→ See [contributing.md](https://github.com/lue-bird/elm-emptiness-typed/blob/master/contributing.md)