Why string alias is invariant ?

[Janice Caron]

On Feb 1, 2008 12:03 AM, Frits van Bommel <fvbommel at remwovexcapss.nl> wrote:
> Some code points
> expand to 2 or 3 codepoints when uppercased. One common case is U+00DF
> "ß", LATIN SMALL LETTER SHARP S, which expands to "SS" (two characters)
> when uppercased[1]. Another example from the Unicode standard, U+0390,
> GREEK SMALL LETTER IOTA WITH DIALYTIKA AND TONOS apparently expands to
> three codepoints.

I know. I would have mentioned that, but I didn't want to needlessly
complicate the issue.

But Unicode makes a distinction between "simple casing" and "full
casing". What you're talking about is full casing. In simple casing,
one character maps to one character. So you could uppercase U+00DF (to
itself) using simple-casing. When using full casing, as you quite
rightly point out, one can only case-change strings, not characters.