doall vs. dorun
Can someone describe a situation where it is preferable to use doall instead of dorun? I see in the documentation that it retains the head and returns it, thus causing the entire seq to reside in memory at one time, but I'm not sure why I'd want that. -- R. Mark Volkmann Object Computing, Inc. --~--~-~--~~~---~--~~ 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 -~--~~~~--~~--~--~---
Re: doall vs. dorun
Pretty much any lazy-seq thats reading data from somewhere that might give up on you if you take to long. For example: Your using line-seq to read from a socket, but the sequence wont be read through until the user does something. On Tue, Jan 20, 2009 at 3:32 PM, Mark Volkmann r.mark.volkm...@gmail.comwrote: Can someone describe a situation where it is preferable to use doall instead of dorun? I see in the documentation that it retains the head and returns it, thus causing the entire seq to reside in memory at one time, but I'm not sure why I'd want that. -- R. Mark Volkmann Object Computing, Inc. -- -Nate --~--~-~--~~~---~--~~ 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 -~--~~~~--~~--~--~---
Re: doall vs. dorun
On Jan 20, 3:32 pm, Mark Volkmann r.mark.volkm...@gmail.com wrote: Can someone describe a situation where it is preferable to use doall instead of dorun? Here's one: (defn read-my-file [] (with-open [reader (BufferedReader. (FileReader. my-file.txt))] (doall (line-seq reader line-seq returns a lazy sequence, but you have to consume that sequence before with-open closes the file. -Stuart Sierra --~--~-~--~~~---~--~~ 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 -~--~~~~--~~--~--~---
Re: doall vs. dorun
In addition to what others have said, I also tend to use doall when working with agent actions that return sequences (i.e. to force any computation to happen in the agent's thread and not in the caller's) Cheers, Mark On Wed, Jan 21, 2009 at 7:32 AM, Mark Volkmann r.mark.volkm...@gmail.com wrote: Can someone describe a situation where it is preferable to use doall instead of dorun? I see in the documentation that it retains the head and returns it, thus causing the entire seq to reside in memory at one time, but I'm not sure why I'd want that. -- R. Mark Volkmann Object Computing, Inc. --~--~-~--~~~---~--~~ 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 -~--~~~~--~~--~--~---
Re: doall vs. dorun
On Tue, Jan 20, 2009 at 3:14 PM, Stuart Sierra the.stuart.sie...@gmail.com wrote: On Jan 20, 3:32 pm, Mark Volkmann r.mark.volkm...@gmail.com wrote: Can someone describe a situation where it is preferable to use doall instead of dorun? Here's one: (defn read-my-file [] (with-open [reader (BufferedReader. (FileReader. my-file.txt))] (doall (line-seq reader line-seq returns a lazy sequence, but you have to consume that sequence before with-open closes the file. How is it different if you change doall to dorun? According to their doc strings, they both can be used to force any effects. Walks through the successive rests of the seq -- R. Mark Volkmann Object Computing, Inc. --~--~-~--~~~---~--~~ 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 -~--~~~~--~~--~--~---
Re: doall vs. dorun
On Jan 20, 2009, at 5:32 PM, Mark Volkmann wrote: Here's one: (defn read-my-file [] (with-open [reader (BufferedReader. (FileReader. my-file.txt))] (doall (line-seq reader line-seq returns a lazy sequence, but you have to consume that sequence before with-open closes the file. How is it different if you change doall to dorun? According to their doc strings, they both can be used to force any effects. Walks through the successive rests of the seq Using doall will cause read-my-file to return a seq of all the lines. dorun will return nil. Here's a simpler example: user= (doall (map #(do (prn %) %) [1 2 3])) 1 2 3 (1 2 3) user= (dorun (map #(do (prn %) %) [1 2 3])) 1 2 3 nil user= (Note the difference in return value.) --Steve smime.p7s Description: S/MIME cryptographic signature
Re: doall vs. dorun
On Tue, Jan 20, 2009 at 4:32 PM, Mark Volkmann r.mark.volkm...@gmail.comwrote: On Tue, Jan 20, 2009 at 3:14 PM, Stuart Sierra the.stuart.sie...@gmail.com wrote: On Jan 20, 3:32 pm, Mark Volkmann r.mark.volkm...@gmail.com wrote: Can someone describe a situation where it is preferable to use doall instead of dorun? Here's one: (defn read-my-file [] (with-open [reader (BufferedReader. (FileReader. my-file.txt))] (doall (line-seq reader line-seq returns a lazy sequence, but you have to consume that sequence before with-open closes the file. How is it different if you change doall to dorun? According to their doc strings, they both can be used to force any effects. Walks through the successive rests of the seq Use dorun when you want to do something purely for the side effects. If you don't need what doall would return then you can use dorun instead to clearly indicate your intent. -- Cosmin Stejerean http://offbytwo.com --~--~-~--~~~---~--~~ 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 -~--~~~~--~~--~--~---
Re: doall vs. dorun
Thanks Steve and Cosmin! I understand it now. On Tue, Jan 20, 2009 at 4:53 PM, Stephen C. Gilardi squee...@mac.com wrote: On Jan 20, 2009, at 5:32 PM, Mark Volkmann wrote: Here's one: (defn read-my-file [] (with-open [reader (BufferedReader. (FileReader. my-file.txt))] (doall (line-seq reader line-seq returns a lazy sequence, but you have to consume that sequence before with-open closes the file. How is it different if you change doall to dorun? According to their doc strings, they both can be used to force any effects. Walks through the successive rests of the seq Using doall will cause read-my-file to return a seq of all the lines. dorun will return nil. Here's a simpler example: user= (doall (map #(do (prn %) %) [1 2 3])) 1 2 3 (1 2 3) user= (dorun (map #(do (prn %) %) [1 2 3])) 1 2 3 nil user= (Note the difference in return value.) --Steve -- R. Mark Volkmann Object Computing, Inc. --~--~-~--~~~---~--~~ 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 -~--~~~~--~~--~--~---
