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Unevaluated Expressions

Syntax

expression(...)

is.expression(expr)
as.expression(expr)

Value

An object with class ``expression'' containing its unevaluated arguments. Expression objects are lists of ``calls'' and so the subsetting operations which apply to lists also apply to them. For compatibility with S, the mode function will return "expression" for expression objects.

is.expression returns TRUE if expr is an expression object and FALSE otherwise.

as.expression attempts to coerce its argument into an expression object.

See Also

call, call.