https://github.com/russelldavies/elm-range

Model and operate on a range of values in Elm
https://github.com/russelldavies/elm-range

elm

Last synced: about 7 hours ago
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Model and operate on a range of values in Elm

• Host: GitHub
• URL: https://github.com/russelldavies/elm-range
• Owner: russelldavies
• License: bsd-3-clause
• Created: 2018-09-08T14:34:39.000Z (over 6 years ago)
• Default Branch: master
• Last Pushed: 2022-02-13T07:05:15.000Z (almost 3 years ago)
• Last Synced: 2023-08-08T20:40:04.609Z (over 1 year ago)
• Topics: elm
• Language: Elm
• Homepage: https://package.elm-lang.org/packages/russelldavies/elm-range/latest/
• Size: 190 KB
• Stars: 2
• Watchers: 2
• Forks: 0
• Open Issues: 3
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE

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README

        
# russelldavies/elm-range

Model and operate on a range of values in Elm.

```elm

Result.map2 Range.merge

    (Range.fromString Range.types.int "[1,5]")

    (Range.fromString Range.types.int "(4,10]")

    |> Result.map Range.toString -- Ok "[1,11)"

```

## Overview

The concept of a range is inspired from PostgreSQL's [Range

Types](https://www.postgresql.org/docs/current/rangetypes.html):

> Range types are data types representing a range of values of some element

> type (called the range's *subtype*). For instance, ranges of `timestamp`

> might be used to represent the ranges of time that a meeting room is

> reserved. In this case the data type is `tsrange` (short for “timestamp

> range”), and `timestamp` is the subtype. The subtype must have a total order

> so that it is well-defined whether element values are within, before, or

> after a range of values.

>

> Range types are useful because they represent many element values in a single

> range value, and because concepts such as overlapping ranges can be expressed

> clearly. The use of time and date ranges for scheduling purposes is the

> clearest example; but price ranges, measurement ranges from an instrument,

> and so forth can also be useful.

## Usage

When creating a range, either from a string or directly from values, you will

need to specify a type. This library provides a few for `Int`, `Float`,

`String`, and `Time.Posix` in the `Range.types` record. If you need a custom

one, you will need to write your own `TypeConfig` (essentially a typeclass).