Sets of characters are useful for text-processing code,
including parsing, lexing, and pattern-matching.
SRFI 14 specifies
a char-set type for such uses. Some examples:
(import (srfi :14 char-sets))
(define vowel (char-set #\a #\e #\i #\o #\u))
(define vowely (char-set-adjoin vowel #\y))
(char-set-contains? vowel #\y) ⇒ #f
(char-set-contains? vowely #\y) ⇒ #t
See the SRFI 14 specification for details.
Type: char-set
The type of character sets.
In Kawa char-set is a type that can be used in type specifiers:
(define vowely ::char-set (char-set-adjoin vowel #\y))
Kawa uses inversion lists for an efficient implementation, using Java int arrays
to represents character ranges (inversions).
The char-set-contains? function uses binary search,
so it takes time proportional to the logarithm of the number of inversions.
Other operations may take time proportional to the number of inversions.
