Re: Comments on SRFI 128 Draft 5 (2015-11-08). John Cowan 09 Nov 2015 17:37 UTC
Sudarshan S Chawathe scripsit: > * Would it be desirable to relax the restrictions noted under > Limitations for comparators created using programmer-defined > type-tests, equality and ordering predicates, and hash function? Only if you don't object to various routines malfunctioning. If equality is not transitive, for example, then =? won't necessarily do what you expect based on your experience of =, string=?, etc. From here on, if I don't mention a comment I have accepted it and will add it. > * Are comparators that reflect a partial ordering of objects > permitted? The definition of ordering predicate seems to permit it. The programmer responsibilities rule that out. If a < b, then it's forbidden for b < a, by the definition of mathematical asymmetry. > * hash function definition: Even though using it is optional, what > is the expected interpretation of the second argument as upper > bound: inclusive or exclusive? I would guess the latter based on > common convention, but a clarification would be helpful. Exclusive. I'll make the next draft say so. > > * comparator-register-default!: What is the behavior if this > procedure is used to register two comparators, both of whose type > test predicates return true for some objects? Unpredictable. I'll say so. > * (very minor) Beginning of Specification: I don't understand the > significance of the choice of the (comparators) library name > instead of (srfi 128), beyond what is stated there. (I realize > this may change when the sample implementation is added/updated.) Not much, really. Development convenience for me. That sentence really should be in the implementation section, as SRFIs as such do not (or at least I think they should not) assume a particular library system. > In particular, is it true that a horrible hash function that always > returns 0 is always technically correct? Yes. Indeed, the sample implementation I'm writing can do no better on procedures and ports. -- John Cowan http://www.ccil.org/~cowan email@example.com LEAR: Dost thou call me fool, boy? FOOL: All thy other titles thou hast given away: That thou wast born with.