https://github.com/wking-io/pair

Canonical Product Type that allows you to hold and use two values in one type.
https://github.com/wking-io/pair

Last synced: about 1 month ago
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Canonical Product Type that allows you to hold and use two values in one type.

• Host: GitHub
• URL: https://github.com/wking-io/pair
• Owner: wking-io
• License: other
• Created: 2019-01-04T16:18:00.000Z (almost 6 years ago)
• Default Branch: master
• Last Pushed: 2019-01-11T17:28:13.000Z (almost 6 years ago)
• Last Synced: 2024-04-08T09:07:10.779Z (7 months ago)
• Language: Elm
• Size: 37.1 KB
• Stars: 0
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Pair

A Product Type that allows you to hold and use two values in one type. This useful for working with more than one related value similar to tuple or list, but since it is limited to only two values the API is more focused.

There are many uses for the Pair type and, if you know of a good one that is not below please add a PR. I use the Pair type primarily for computations on values that have "metadata" or some extra information about the value that needs to travel with it.

```elm

import Pair

-- A math example

average : List Float -> Float

average list =

  list

    |> Pair.branchWith List.sum List.length

    |> Pair.merge (/)

average [ 9, 11, 34 ] -- > 18

-- More complex example.

type alias Item =

  { name : String

  , cost : Float

  }

sumCart : List Items -> Float

sumCart items =

  List.foldl (\acc { price } -> total + price ) 0 items

calculateCart : List Items -> Pair (List Items) Float

calculateCart items =

    branch items

      |> Pair.map sumCart

calculateCart

  [ { name = "Apple", price = 0.75 }

  , { name = "Banana", price = 0.53 }

  , { name = "Tangerine", price = 0.98 }

  ]

{- > Pair

        [ { name = "Apple", price = 0.75 }

        , { name = "Banana", price = 0.53 }

        , { name = "Tangerine", price = 0.98 }

        ]

        2.26

-}

```