By the way just to clarify, the use of recur is iterative, it's just written in clojure in its recursive form.
On Jan 11, 1:32 am, "Nick Vogel" <voge...@gmail.com> wrote: > Ok, first of all, here's how I translated that python code: > > (defn msort [myList] > (if (> (count myList) 1) > (let [l1 (first myList) l2 (second myList)] > (recur (concat (drop 2 myList) (my-merge l1 l2)))) > (first myList))) > > The main thing that might need explaining is the recur, which basically goes > back to either the last function definition or last loop and rebinds > whatever parameters werre passed in. In this case it goes back and is as if > it's calling msort with (concat (drop 2 myList) (my-merge l1 l2)) as > myList. The let is just for clarity's sake, you could have just put them in > place of l1 and l2 in the recur. > > On Sun, Jan 11, 2009 at 12:21 AM, e <evier...@gmail.com> wrote: > > > I'm just trying to understand basic stuff. > > say I have a local list called "myList" (assigned using 'let' . . . > > should I have used something else?) Who cares what's in it. Maybe I > > set it up from a list comprehension from some input to my function. > > > I have no idea how to iteratively mess with it since everything is > > persistent. Ok, like, say it's a list of lists and I am going to be > > merging the lists, like Tarjan's mergesort from some book from > > college. > > > so I have myList with contents [[11] [2] [4] [1] [99]] > > > here's how I would do it in python: > > > def msort(myList): > > myList = [[x] for x in someList] > > while len(myList) > 1: > > l1 = myList.pop(0) > > l2 = myList.pop(0) > > listmerge = some_merge_function(l1, l2) > > myList.append(listmerge) # important that newly merged go > > to back of queue to get proper runtime > > return myList[0] > > > here's what I'm trying to do for clojure, and it's a mess: > > > (defn msort [toSort] > > (def sorted (let > > [myList (for [x toSort] [x])] <----- so far so good (not a > > real comment. I don't know how, yet) > > [ > > (while (> (count myList) 1) <------- infinite loop the way > > written? I don't know how to overwrite myList > > (let [l1 (nth myList 0)][]) > > (let [l2 (nth myList 1)][]) > > (let [listmerge (some_merge_func l1 l2)][]) > > (let [myList (concat (drop 2 myList) listmerge)][myList]) <--- > > probably a different local variable > > ) > > ])) > > sorted) > > > doesn't compile anyway . . . I see that the let is causing the scope > > to be all screwed up. l1 and l2 can't be seen for the merge function. > > > should I be using let at all here? Can things be redefined using > > def? see how much simpler it is not to say anything? Which is > > it .... def or let in python? Answer: No . . .but I'm sure there's > > value. This seems like something that might be in the FAQ. . . .or > > somewhere back in these discussions. I'll look around. > > > Thanks. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
