This package implements a simple `Interval` type for [Elm](http://elm-lang.org).
Various functionality is included for constructing intervals (including as the
hull or intersection of other intervals), checking for
overlap/intersection/containment, and performing limited arithmetic on
intervals:

```elm
unitInterval =
    Interval.from 0 1

Interval.endpoints unitInterval
--> ( 0, 1 )

Interval.containingValues [ 2, 1, 3 ]
--> Just (Interval.from 1 3)

Interval.hull
    (Interval.from 1 2)
    (Interval.from 3 5)
--> Interval.from 1 5

Interval.intersection
    (Interval.from 1 3)
    (Interval.from 2 5)
--> Just (Interval.from 2 3)

Interval.intersection
    (Interval.from 1 2)
    (Interval.from 3 5)
--> Nothing

Interval.contains 0 (Interval.from -1 3)
--> True

Interval.contains 5 (Interval.from -1 3)
--> False

Interval.sin (Interval.from 0 pi)
--> Interval.from 0 1
```

Currently the only functions that have been implemented are ones that were
needed by the `elm-geometry` package, but I'm happy to consider pull requests
for other generally-useful functionality. Please [open a new issue](https://github.com/ianmackenzie/elm-interval/issues)
before starting work, though, so we can discuss different approaches!