I just got bit by (clojure.contrib.lazy-seqs/combinations) returning nil, not [[]] as I expected. I could see arguments for either being the "correct" output, but let me give my case for [[]].
In my mind, asking what the output of (combinations) should be is completely analogous to asking what the value of 0^0 should be. Either 0 or 1 seems defensible, but the accepted answer is 1 (for reasons I won't go into here). Similarly, Clojure (*) ==> 1. If you don't see the connection, note that for all non-empty seqs of seqs "args", (= (count (apply combinations args)) (apply * (map count args))). If (= (combinations) [[]]), then this would hold always. Plus, this is what would make it work in my application. I can go into more details if you like, but the basic idea use case is finding the set of all allowed variable bindings, given a possible set of possible values for each variable. If there are no variables, this set should consist of the single "empty binding" rather than "no bindings possible". Will anyone sign off on adding this as a clojure.contrib issue? Thanks, Jason --~--~---------~--~----~------------~-------~--~----~ 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 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 -~----------~----~----~----~------~----~------~--~---
