converts a full form of an expression expr, representing some valid R object, to the short form. Returns $Failed on illegal expressions, which do not form a valid RLink representation of an R object.
- Performs the reverse operation as compared to ToRForm.
- Is invoked automatically by REvaluate, as a final step to transform the internal full form of an expression obtained from R to a short form, which is easier to use.
- While sometimes useful for consistency checks and debugging, it is not expected that this function will be called often.
- The "cycle" FromRForm[ToRForm[expr]] should always give back the same expression expr (for legitimate expr, representing valid R objects), except when expr is a scalar of one of the primitive types (numeric, string, or logical), in which case it will be "dressed" in an extra List.