Example: Java Identifiers
Regex matching a Java identifier:
[\p{Connector_Punctuation}\p{Currency_Symbol}\p{Mark}\p{Alphabetic}][\p{Connector_Punctuation}\p{Currency_Symbol}\p{Mark}\p{Alphabetic}\p{Numeric}]*
With abbreviations:
[\p{Pc}\p{Sc}\p{M}\p{Alpha}][\p{Pc}\p{Sc}\p{M}\p{Alpha}\p{Numeric}]*
And as a Pomsky:
[Pc Sc M Alpha]
[Pc Sc M Alpha Numeric]*