Choice null-combination

The value of the null combination, (), strikes me as having endless potential for bikeshed debates. The R5RS does not settle these debates, for it does not content itself with saying, as it does for so many other things, "It is an error to evaluate the empty list," nor does it place the empty list into the set of self-evaluating things. Rather, it says that the empty list is not a valid combination, thus disclaiming any responsibility for defining the meaning of applying the absence of a procedure, but in the same stroke also leaving the value of the empty list up to implementor discretion. Fortunately, Schemes seem to only do one of two things when put to the task of evaluating the empty list.

This choice is tested for by running

()

in each Scheme.