| is.language {base} | R Documentation |
is.language returns TRUE if x is either a
variable name, a call, or an
expression.
is.language(x)
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)
stopifnot(sapply(ll, is.language))