+It was important to us to extend the space of identifiers from the +confines of ASCII. Go's rule—identifier characters must be +letters or digits as defined by Unicode—is simple to understand +and to implement but has restrictions. Combining characters are +excluded by design, for instance. +Until there +is an agreed external definition of what an identifier might be, +plus a definition of canonicalization of identifiers that guarantees +no ambiguity, it seemed better to keep combining characters out of +the mix. Thus we have a simple rule that can be expanded later +without breaking programs, one that avoids bugs that would surely arise +from a rule that admits ambiguous identifiers. +
+ +
+On a related note, since an exported identifier must begin with an
+upper-case letter, identifiers created from “letters”
+in some languages can, by definition, not be exported. For now the
+only solution is to use something like X日本語, which
+is clearly unsatisfactory; we are considering other options. The
+case-for-visibility rule is unlikely to change however; it's one
+of our favorite features of Go.
+