[dpkendal]

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.

[fhars]

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"...

[dpkendal]

Unicode has things for this: https://en.wikipedia.org/wiki/Zero-width_non-joiner

And customization is done declaratively, not imperatively.