Hi, 2009/5/8 Mark Reid <mark.r...@gmail.com>
> > Hi, > > This `lazy-seq` over a `when` and `cons` idiom seems fairly common. Is > there any reason there is not a function for it? For example: > > (defn cons-while > "Lazily creates a sequence by repeatedly calling f until pred is > false" s/false/logical false/ > > [pred f] > (lazy-seq > (when pred > (cons f (cons-while pred f))))) > > I haven't tested it but I suspect the following should now work: > > (cons-while (Mouse/hasEvent) (Mouse/getEvent)) (cons-while #(Mouse/hasEvent) #(Mouse/getEvent)) or maybe create a general version of repeatedly-while : (defn repeatedly-while [pred f] (take-while pred (repeatedly f))) and call it like this also: (repeatedly-while #(Mouse/hasEvent) #(Mouse/getEvent)) Then I remark it is just a minor variation on Meikel's first answer : (take-while #(no-op-pred) (repeatedly f))) (not tested) > > Regards, > > Mark > -- > http://mark.reid.name > > On May 8, 7:44 am, Meikel Brandmeyer <m...@kotka.de> wrote: > > Hi, > > > > lazy-seq to the rescue: > > > > (defn mouse-seq > > [] > > (lazy-seq > > (when (Mouse/hasEvent) > > (cons (Mouse/getEvent) (mouse-seq))))) > > > > Sincerely > > Meikel > > > > Am 07.05.2009 um 23:40 schrieb CuppoJava: > > > > > > > > > > > > > Yeah (pred) is not supposed to depend on any items inside f. > > > > > This is why (take-while pred (repeatedly f))) > > > won't work in this situation. > > > > > (take-while) will always take an element out of f, so that it can be > > > tested using (pred). I don't want any elements of (f) to be looked at > > > if (pred) is false. > > > > > ----USE CASE---- > > > I'm using it in combination with some Java libraries. The following > > > seems like a very clojure-ish way of doing things. > > > > > (for [:while (Mouse/hasEvent)] (Mouse/getEvent)) > > > > > so this returns a nice lazy stream of mouse events, which can be > > > processed however i like. > > > > > > > > > > smime.p7s > > 5KViewDownload > > > > --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
