I agree. At this point scripting languages should have native support for string subtypes with custom charsets (ascii/utf16) or just regexp-defined or even ENUM()'erated values.

IIRC historically on Windows, a string was UTF16, on unix it was ASCII; nowadays everywhere it's UTF8 without a way to specifically limit what goes into a string.

For example UTF8 opens the door to homoglyph attacks and various other things (RTL, spaces), and a program should be able to force a string to be ASCII-only so that these classes of problems are ruled out.