Document unicode report deviations
The report specifies “Haskell compilers are expected to make use of new versions of Unicode as they are made available.” So if we deviate from that, we should make sure that
- the user’s guide explicitly lists all deviations from the report in this section, and
- that the Haskell prime committee is going to be aware of these (sensible) deviations, so that they can become official.
Certain deviations are (there might be more):
OtherLetterare treated as lowercase (#1103 (closed)), and thus allowed in identifiers.
OtherNumber(#4373 (closed)) and
NonSpacingMark(#7650 (closed)) are allowed in identifiers, but only starting from the second character.
$decdigit = $ascdigit -- for now, should really be $digit (ToDo)(see compiler/parser/Lexer.x)