https://github.com/eeue56/elm-all-dict

A dict for Elm which can store any type
https://github.com/eeue56/elm-all-dict

Last synced: about 1 month ago
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A dict for Elm which can store any type

• Host: GitHub
• URL: https://github.com/eeue56/elm-all-dict
• Owner: eeue56
• Created: 2015-10-31T19:36:07.000Z (about 9 years ago)
• Default Branch: master
• Last Pushed: 2018-02-19T18:07:42.000Z (almost 7 years ago)
• Last Synced: 2024-05-22T01:07:09.993Z (8 months ago)
• Language: Elm
• Size: 25.4 KB
• Stars: 36
• Watchers: 3
• Forks: 5
• Open Issues: 2
• Metadata Files:
  • Readme: README.md

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README

        
# elm-all-dict

This library provides two Dict implementations. Firstly, it provides `AllDict`, a dictionary which you may pass a hashing function in order to allow all types to be stored as keys.

Secondly, it provides `EveryDict`, a dictionary which uses `toString` as a hashing function.

This is a dictionary based off of core's Dict implementation, except it can support any type, rather than just `comparable`s. A function must be given which will hash the key into a `comparable`.

```elm

module Main where

import Graphics.Element exposing (show)

import AllDict exposing (AllDict)

import EveryDict exposing (EveryDict)

type Action = Run | Hide | StandStill

ord : Action -> Int

ord action =

    case action of

        Run -> 0

        Hide -> 1

        StandStill -> 2

actionDict : AllDict Action String Int

actionDict =

    AllDict.fromList

        ord

        [ (Run, "Run away!")

        , (Hide, "Coward!")

        , (StandStill, "Err...")]

actionDict2 : EveryDict Action String

actionDict2 =

    EveryDict.fromList

        [ (Run, "Run away!")

        , (Hide, "Coward!")

        , (StandStill, "Err...")]

main = show <| EveryDict.toList actionDict2

```

## EveryDict

EveryDict uses a custom implementation of `toString` in order to allow functions to be used as keys. The current implementation of `toString` doesn't actually work properly when functions are defined in the format

```javascript

var f = function() ...

```

This is down to the fact `toString` uses the `.name` of the functions - this is obviously not defined when using the variable binding to anonymous functions that is common in JS.