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Michael Sperber <sperber@xxxxxxxxxxxxxxxxxxxxxxxxxxx> writes: > >>>>> "Tom" == Tom Lord <lord@xxxxxxx> writes: > > Tom> Either way, these "constants" wind up having exactly the same style of > Tom> interface as SCHEME_ENTER_* rather than a special case interface that > Tom> refers to their traditional implementation using immediate > Tom> representations. > > OK, point taken. But why is that a reason to have SCHEME_FALSE() > instead of SCHEME_FALSE? (Alternatively: why does Scheme allow EQ? to > work on booleans, and use #f instead of (false)?) I have no objection to exactly which C function should be used to check for falsity. My insistence is that it should always look like a function, and not like a C constant; nor should C's == be used to compare Scheme objects. There may well be more than one C object which all collectively represent the same Scheme object, and which are eq? to each other, but not == to each other. So the SRFI better not constrain an implementation. It cannot promise to a C programmer that SCHEME_FALSE is a constant, hence it should be SCHEME_FALSE() which returns a false value. Then it cannot promise that the following tests whether foo is #f: foo == SCHEME_FALSE() so it must have something like SCHEME_EQ(foo, SCHEME_FALSE()) This is about making sure that the C syntax does not forclose certain sensible Scheme implementation strategies. Thomas