The Unicode case-mapping algorithm is customizable by locale (e.g. uppercase i is İ in Turkish). A application which needed long s (for German Fraktur, for instance) could use a custom locale.
Specifying the rules for German Fraktur as executable code will be fun, as it uses the short s at the end of syllables, not words. So it is "Häschen" and "Häſcher"...