Thanks, Mark. I don't suppose (reduce into ...) is a common enough idiom that it deserves its own function? Perhaps (into x) should do (reduce into x), e.g. (into [[3 5] [6 7]]) => [3 5 6 7]. This makes sense to me, but maybe it's too semantically different from (into x y). If not, though, you could do the same with concat.
On Dec 12, 3:10 pm, Mark Fredrickson <mark.m.fredrick...@gmail.com> wrote: > > For (1), it seems you generally resort to some kind of recursion with > > loop/recur. Say we wish to find the max value in a list (without using > > 'max'): > > I can do this with reduce: > user=> (defn my-max [lst] (reduce (fn [x a] (if (> x a) x a)) (first > lst) (rest lst))) > #'user/my-max > user=> (my-max '(2 4 12 3 4)) > 12 > > For more complex data that you need to bring along, use a list or map. > > > For (2), say I want to insert 3 before every item less than or equal > > to 5 in a seq: > > Again reduce to the rescue: > > (reduce into (map (fn [i] (if (<= i 5) [3 i] [i])) [24 6 5 5 7 5 8 2])) > > This is still O(n) - though it needs to iterate the vector twice. The > second version shows off Clojure's nice improvement to reduce (vis-a- > vis fold in Scheme): grabbing the first item from the head of the list/ > vec/seq. The down side is I can't write multi-sequence reduce calls > like Scheme, but c'est la vie. > > I could write O(n) versions with continuations in Scheme, but I think > loop/recur would be required in Clojure. > > Cheers, > -Mark --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
