Re: Map a list of agents to a list of their values
Hi, Am 14.11.2009 um 20:31 schrieb John Harrop: For situations like this, I find it handy to discover what reader- macros are expanding to. This works well: user=(defmacro expand [arg] (println arg)) #'user/expand user=(expand #(@%)) (fn* [p1__6536] ((clojure.core/deref p1__6536))) user= (macroexpand-1 '#(@%)) (fn* [p1__13] ((clojure.core/deref p1__13))) ;) Sincerely Meikel smime.p7s Description: S/MIME cryptographic signature
Re: Map a list of agents to a list of their values
On Sat, Nov 14, 2009 at 6:03 PM, Meikel Brandmeyer m...@kotka.de wrote: Hi, Am 14.11.2009 um 20:31 schrieb John Harrop: For situations like this, I find it handy to discover what reader-macros are expanding to. This works well: user=(defmacro expand [arg] (println arg)) #'user/expand user=(expand #(@%)) (fn* [p1__6536] ((clojure.core/deref p1__6536))) user= (macroexpand-1 '#(@%)) (fn* [p1__13] ((clojure.core/deref p1__13))) Funny, I get user= (macroexpand-1 '#(@%)) (fn* [p1__6540] (@p1__6540)) as apparently the Enclojure REPL turns (deref foo) back into @foo when printing it. In fact I fiddled with the macro just because '#(@%) by itself at my REPL just echoed itself. But this does work: user= (prn '#(@%)) (fn* [p1__6544] ((clojure.core/deref p1__6544))) So does temporarily clicking off pretty-printing at the REPL and just evaluating '#(@%). On the other hand, the macro's argument doesn't need to be quoted, so there's one less awkward-to-type punctuation character. :) -- 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 Note that posts from new members are moderated - please be patient with your first post. 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: Map a list of agents to a list of their values
Try (map deref agents) On Nov 14, 12:49 pm, Kevin Q kevin.jing@gmail.com wrote: I have a list of agents, each of which has a hasmap state. I want to get a list of values from the list of agents, naturally I used the map function and print the result of the map: (println (map #(@%) agents)) However, when I run this, I got error Wrong number of args passed to: PersistentHashMap I'm wondering why is this happening? Prior to calling the map function, I did (apply await agents) to wait for all my agents to finish. Does it affect things? 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 Note that posts from new members are moderated - please be patient with your first post. 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: Map a list of agents to a list of their values
On Sat, Nov 14, 2009 at 12:49 PM, Kevin Q kevin.jing@gmail.com wrote: I have a list of agents, each of which has a hasmap state. I want to get a list of values from the list of agents, naturally I used the map function and print the result of the map: (println (map #(@%) agents)) However, when I run this, I got error Wrong number of args passed to: PersistentHashMap I'm wondering why is this happening? For situations like this, I find it handy to discover what reader-macros are expanding to. This works well: user=(defmacro expand [arg] (println arg)) #'user/expand user=(expand #(@%)) (fn* [p1__6536] ((clojure.core/deref p1__6536))) So it will have the same effect as (map deref agents), though the latter is clearer. I don't know why it's failing, but it seems unlikely that switching to (map deref agents) will fix it. -- 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 Note that posts from new members are moderated - please be patient with your first post. 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: Map a list of agents to a list of their values
Thanks! That works. However, why wouldn't (map #(@%) agents) work? On Nov 14, 1:01 pm, Sean Devlin francoisdev...@gmail.com wrote: Try (map deref agents) On Nov 14, 12:49 pm, Kevin Q kevin.jing@gmail.com wrote: I have a list of agents, each of which has a hasmap state. I want to get a list of values from the list of agents, naturally I used the map function and print the result of the map: (println (map #(@%) agents)) However, when I run this, I got error Wrong number of args passed to: PersistentHashMap I'm wondering why is this happening? Prior to calling the map function, I did (apply await agents) to wait for all my agents to finish. Does it affect things? 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 Note that posts from new members are moderated - please be patient with your first post. 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: Map a list of agents to a list of their values
Hi, Thanks for the hint. I tried (map deref agents) and it did work. I don't know if this is a bug? On Nov 14, 2:31 pm, John Harrop jharrop...@gmail.com wrote: On Sat, Nov 14, 2009 at 12:49 PM, Kevin Q kevin.jing@gmail.com wrote: I have a list of agents, each of which has a hasmap state. I want to get a list of values from the list of agents, naturally I used the map function and print the result of the map: (println (map #(@%) agents)) However, when I run this, I got error Wrong number of args passed to: PersistentHashMap I'm wondering why is this happening? For situations like this, I find it handy to discover what reader-macros are expanding to. This works well: user=(defmacro expand [arg] (println arg)) #'user/expand user=(expand #(@%)) (fn* [p1__6536] ((clojure.core/deref p1__6536))) So it will have the same effect as (map deref agents), though the latter is clearer. I don't know why it's failing, but it seems unlikely that switching to (map deref agents) will fix it. -- 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 Note that posts from new members are moderated - please be patient with your first post. 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: Map a list of agents to a list of their values
On Sat, Nov 14, 2009 at 2:51 PM, Kevin Q kevin.jing@gmail.com wrote: Hi, Thanks for the hint. I tried (map deref agents) and it did work. I don't know if this is a bug? Nah, it's just being really sneaky. (fn* [p1__6536] ((clojure.core/deref p1__6536))) Even I didn't notice it before. There's an extra pair of parens, so it's double-dereferencing. The problem is that #() brings in one pair, and @ in expanding to (deref the-argument) brings in a second. Just use (map deref agents). General advice: Avoid directly using another reader macro inside #(); the first thing should always be a symbol or a call that evaluates to a function, e.g. #((function-returning-function arg) other-arg). -- 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 Note that posts from new members are moderated - please be patient with your first post. 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: Map a list of agents to a list of their values
On Sat, Nov 14, 2009 at 3:24 PM, John Harrop jharrop...@gmail.com wrote: On Sat, Nov 14, 2009 at 2:51 PM, Kevin Q kevin.jing@gmail.com wrote: Hi, Thanks for the hint. I tried (map deref agents) and it did work. I don't know if this is a bug? Nah, it's just being really sneaky. (fn* [p1__6536] ((clojure.core/deref p1__6536))) Even I didn't notice it before. There's an extra pair of parens, so it's double-dereferencing. The problem is that #() brings in one pair, and @ in expanding to (deref the-argument) brings in a second. As for the seemingly irrelevant error message: I guess the agent's state was a map, so it deref'd it and then invoked the map. Maps can be invoked, but expect one argument (a key to look up) and it got zero. If the error had been cannot cast to IFn, it would have been more apparent what was happening quicker. There isn't much that can be done about the error message confusion in cases like this, though; it goes with the territory of having a highly dynamic language. Learning to interpret them is an art, one I'm still mastering. -- 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 Note that posts from new members are moderated - please be patient with your first post. 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
