A set of Chars.

We use range set, which works great with Char.

Empty character set.

universe

>>> size universe
1114112

>>> universe
CS.fromIntervalList [('\NUL','\1114111')]

Singleton character set.

Insert Char into CharSet.

Union of two CharSets.

Intersection of two CharSets

Complement of a CharSet

Difference of two CharSets.

Size of CharSet

>>> size $ fromIntervalList [('a','f'), ('0','9')]
16

>>> length $ toList $ fromIntervalList [('a','f'), ('0','9')]
16

Check whether CharSet is empty.

Test whether character is in the set.

Make CharSet from a list of characters, i.e. String.

Convert CharSet to a list of characters i.e. String.

Convert from interval pairs.

>>> fromIntervalList []
""

>>> fromIntervalList [('a','f'), ('0','9')]
"0123456789abcdef"

>>> fromIntervalList [('Z','A')]
""

Convert to interval list

>>> toIntervalList $ union "01234" "56789"
[('0','9')]