elm-natural-ordering

This package provides comparison functions to sort strings containing numbers and diacritics in an expected way.

Take the following list for example:

names : List String
names =
    [ "File (1).txt"
    , "File (2).txt"
    , "File (10).txt"
    , "a file"
    , "file (3).txt"
    , "File (15).txt"
    , "A File"
    , "file (100).txt"
    , "File (20).txt"
    , "Á file"
    ]

Sorting them, even ignoring case, yields a confusing result:

List.sortBy String.toLower names
{-
[ "a file"
, "A File"
, "File (1).txt"
, "File (10).txt"
, "file (100).txt"
, "File (15).txt"
, "File (2).txt"
, "File (20).txt"
, "file (3).txt"
, "Á file"
]
-}

People see this list as being out of order, since the files are numbered and the numbers are not ordered. Also letters with diacritics are sorted after any letters without diacritics.

NaturalOrdering.compare solves this:

List.sortWith NaturalOrdering.compare names
{-
[ "a file"
, "A File"
, "Á file"
, "File (1).txt"
, "File (2).txt"
, "file (3).txt"
, "File (10).txt"
, "File (15).txt"
, "File (20).txt"
, "file (100).txt"
]
-}

NaturalOrdering exports a compare function instead of a sort function because it's more composable. You can use it with any data structure that exposes a sortWith : (a -> a -> Ordering) -> f a -> f a function, like a non-emptylist!