String functions behavior depens on target (Unicode support)

[ov7a]

C target treat strings as ASCII:

koka/kklib/src/string.c

Line 831 in a39737a

t[i] = kk_ascii_tolower(s[i]);

while JS treats them as unicode:
https://tc39.es/ecma262/multipage/text-processing.html#sec-string.prototype.tolowercase

Simple reproducer:

$ echo 'println("Добар Дан".to-lower)' | koka --target c
...
Добар Дан
$ echo 'println("Добар Дан".to-lower)' | koka --target js
...
добар дан

trim operation is also affected by this. In JS it's Unicode, while in C it's not:

$ echo 'println("a\xA0".trim ++ ".")' | koka --target c
...
a .
$ echo 'println("a\xA0".trim ++ ".")' | koka --target js
...
a.

As a user, I'd expect that all targets support Unicode.