status: final (2000/12/28)
The ability to efficiently represent and manipulate sets of characters is an unglamorous but very useful capability for text-processing code -- one that tends to pop up in the definitions of other libraries. Hence it is useful to specify a general substrate for this functionality early. This SRFI defines a general library that provides this functionality.
It is accompanied by a reference implementation for the spec. The reference implementation is fairly efficient, straightforwardly portable, and has a "free software" copyright. The implementation is tuned for "small" 7 or 8 bit character types, such as ASCII or Latin-1; the data structures and algorithms would have to be altered for larger 16 or 32 bit character types such as Unicode -- however, the specs have been carefully designed with these larger character types in mind.
Several forthcoming SRFIs can be defined in terms of this one: