null-combinationThe 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.