On 23 February 2010 00:17, Eugen Dück <eu...@dueck.org> wrote: > Rather than having a separate fn 'distinct-by' in addition to the > existing 'distinct', which, apart from the hard-coded keyfn would be > EXACTLY the same, shouldn't we just generalize distinct to default to > hard-coded if no keyfn is specified? (Btw I'm not considering my other > suggestion to allow the set to be passed in here, which I personally > like, but also understand can be seen as unorthogonal) > > And this is not only true for distinct-by, it's true for some of the > other * / *-by pairs. It just seems this should be generalized in > order not to duplicate code for these cases. If we copy-and-paste > code, what's the justification? I'd say orthogonality is an argument > against copy-and-paste. Do we copy and paste rather than generalize in > order to have distinct a little bit faster due to it being hard-coded?
That seems like a very good point to me! Especially if clojure.core/identity could be inlined by the compiler (which I thought it is, although now that I look the inlining-related entries are missing from (meta #'identity)), both distinct and sort could be arity overloaded to accept an optional keyfn or not (sort would basically have to be replaced with sort-by + an added unary variant with defaults for both keyfn and comparator). Then perhaps we could reuse the *-by names for Haskell-style binary predicate-based versions. Haskell's sortBy, groupBy, nubBy all take binary functions to decide ordering / equality of pairs of elements from the input sequence... That's enables some neat code sometimes, cf. the primes on liner. How about that? Sincerely, Michał -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
