In the following MWE the declared keywords te-st and 999 are not highlighted as expected:
\documentclass{scrartcl}
\usepackage{listings,xcolor}
\lstdefinelanguage{mylang}{keywords={test,te-st,999,xyz},keywordstyle=\color{red}}
\begin{document}
\begin{lstlisting}[language=mylang,basicstyle=\ttfamily]
abc test
def te-st
ghi 999
jkl xyz
\end{lstlisting}
\end{document}

How can I define keywords like 999 or te-st?
-and9behave as letters:alsoletter={-9}– egreg May 27 '14 at 12:20