\Header{is.language}{Is an Object a Language Object?}
\keyword{programming}{is.language}
\begin{Usage}
\begin{verbatim}is.language(x)\end{verbatim}
\end{Usage}
\begin{Description}
\texttt{is.language} returns \texttt{TRUE} if \texttt{x} is either a
variable \texttt{\Link{name}}, a \texttt{\Link{call}}, or an
\texttt{\Link{expression}}.\end{Description}
\begin{Examples}
\begin{ExampleCode}
ll <- list(a=expression(x^2 - 2*x + 1), b= as.name("Jim"),
	   c=as.expression(exp(1)), d=call("sin",pi))
sapply(ll, typeof)
sapply(ll, mode)
sapply(ll, is.language)# all TRUE
\end{ExampleCode}
\end{Examples}

