Re: anonymous fn or partial?
> There is a subtle difference in how fixed arguments are handled. > partial evaluates the arguments only once while fn evaluates them on > each call. For side-effects free code the former can yield better > performance. To recap: Ah! What a nice caveat! (also applies to taking macros as arguments). Thanks for your insights, U -- 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: anonymous fn or partial?
There is a subtle difference in how fixed arguments are handled. partial evaluates the arguments only once while fn evaluates them on each call. For side-effects free code the former can yield better performance. To recap: (partial foo (baz 1 2)) == (let [b (baz 1 2)] (fn [& x] (apply foo b x)) As for syntax sugar, I would like to see the #() macro to be extended so that it curries when no implicit arguments are given: #(foo bar baz) => #(foo bar baz &%) whilst keeping (and emphasising) partial for cases where evaluate-once semantics are required. -- 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: anonymous fn or partial?
Am 30.09.2010 13:46, schrieb Nicolas Oury: Note that you can't make readermacros yet. It's a supported in CL not in Clojure but maybe in future versions how knows. I meant, if you want to modify Clojure to allow a shorter notation for partial application, it is better to add a reader macro (directly in Clojure) than to change evaluation semantic I am not sure it is a good idea anyway... I brought this issue up in late 2008 and Rich decided against a reader macro for that, as there already is the #() notation, which also has advantages over partial, namely allowing you to call macros. (map #(and true %) [1 2 3 nil 5]) ==> (1 2 3 nil 5) but (map (partial and true) [1 2 3 nil 5]) ==> Can't take value of a macro: #'clojure.core/and And this would also be the case for a currying reader macro. -- 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: anonymous fn or partial?
> Note that you can't make readermacros yet. It's a supported in CL not > in Clojure but maybe in future versions how knows. I meant, if you want to modify Clojure to allow a shorter notation for partial application, it is better to add a reader macro (directly in Clojure) than to change evaluation semantic I am not sure it is a good idea anyway... -- 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: anonymous fn or partial?
> > If you want to have something looking like (+ 2) with multiple args > > possible, I would advocate the best way might be to > > add a reader macro to clojure expanding to partial. #p(+ 2) for example. > > It is a better idea than using having evaluation depending of the context, > > IMHO. > > I guess that this has just led me into learning yet another bit which > I wasn't even aware of! Thanks! Note that you can't make readermacros yet. It's a supported in CL not in Clojure but maybe in future versions how knows. I think the have random nummer of args vs currying its a good traidoff. -- 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: anonymous fn or partial?
> The two styles are ok. > Matter of taste. > (partial ...) have probably a slight cost I wouldn't worry about > except if profiler tells me to worry. Excellent. > If you want to have something looking like (+ 2) with multiple args > possible, I would advocate the best way might be to > add a reader macro to clojure expanding to partial. #p(+ 2) for example. > It is a better idea than using having evaluation depending of the context, > IMHO. I guess that this has just led me into learning yet another bit which I wasn't even aware of! Thanks! U -- 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: anonymous fn or partial?
The two styles are ok. Matter of taste. (partial ...) have probably a slight cost I wouldn't worry about except if profiler tells me to worry. The (partial...) style is called point-less, because you directly manipulate the arrows and not the points. It is the same kind of question as : should you use composition or call (f (g x))? Should I use the do-monad notation or a clever combination of m-bind, map, and composition? No good answer. Do what you like best in each situation. If you want to have something looking like (+ 2) with multiple args possible, I would advocate the best way might be to add a reader macro to clojure expanding to partial. #p(+ 2) for example. It is a better idea than using having evaluation depending of the context, IMHO. -- 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: anonymous fn or partial?
Hi, On 30 Sep., 12:10, Ulises wrote: > My question stemmed from the fact that sometimes I find myself mapping > functions which are just partial applications of the same function and > perhaps having a bunch of partials lying around would make my code > read better. Well. In case it scratches your itch, I don't see a reason why not to use partial. (Performance implications of the apply should be a concern when the prove to be a problem) Sincerely Meikel -- 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: anonymous fn or partial?
> Think about it for a moment. What should ((+ 2) 1) return? A > function with the next elment add on to it? So it would return a > function that adds 3 to its args or the result? How can you know what > the caller wants? That's a very good point which I hadn't considered. Perhaps the evaluation result could depend on the context? E.g. (def add-2 (partial + 2)) (def add-3 (add-2 1)) Then, hopefully: (add-3 3) ; 6 (add-3); 3 U -- 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: anonymous fn or partial?
> You can also consider the following: (map #(+ % 2) [1 2 3 4]), which I did consider #(...) but didn't include it in the example as I tend to prefer (fn [..] ...). For some reason my brain parses (fn...) much better than #() (it looks more explicit). If partial is a special case of #(..) could there be then a performance penalty of using apply instead of a direct call? My question stemmed from the fact that sometimes I find myself mapping functions which are just partial applications of the same function and perhaps having a bunch of partials lying around would make my code read better. Cheers for all the replies, U -- 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: anonymous fn or partial?
Hi, On 30 Sep., 09:48, Ulises wrote: > user=> (map (fn [n] (+ 2 n)) [1 2 3 4 5]) > (3 4 5 6 7) > user=> (map (partial + 2) [1 2 3 4 5]) > (3 4 5 6 7) > user=> You can also consider the following: (map #(+ % 2) [1 2 3 4]), which is also very clear. I personally almost never use partial. (partial + 2) is not entirely equivalent to #(+ 2 %) - actually it's #(apply + 2 %&) - but for 95% of my use cases the #() form is sufficient, shorter, easier to read for me. partial is just a special case of #(). So in the end it's probably personal preference. Sincerely Meikel -- 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: anonymous fn or partial?
I ask myself that from time to time. I tend to use (partial + 2) because I think its easier to read. The (+ 2) bit is intressting. That would be automatic currying, you get that in other languages. It is not possible in Clojure becaus there is no limit to how many args a clojure function can take. Think about it for a moment. What should ((+ 2) 1) return? A function with the next elment add on to it? So it would return a function that adds 3 to its args or the result? How can you know what the caller wants? Thats the reason for partial. I would have liked a shorter word for partial but its not really importend. On Sep 30, 9:48 am, Ulises wrote: > Hi, > > Newbie here with a simple question: what is the preferred way of > mapping a function to a seq? Use an anonymous function or use a > partial? > > Consider this: > > user=> (map (fn [n] (+ 2 n)) [1 2 3 4 5]) > (3 4 5 6 7) > user=> (map (partial + 2) [1 2 3 4 5]) > (3 4 5 6 7) > user=> > > I know that the answer is likely to be "it depends." I am just > interested in whether one is more idiomatic/functional than the other, > performance issues that one approach may have that the other one > doesn't, etc. > > Thanks in advance, > > PS: I'm even tempted to say that if one could do (map (+ 2) [1 2 3 4 > 5]) it would look even better :) > > U -- 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
anonymous fn or partial?
Hi, Newbie here with a simple question: what is the preferred way of mapping a function to a seq? Use an anonymous function or use a partial? Consider this: user=> (map (fn [n] (+ 2 n)) [1 2 3 4 5]) (3 4 5 6 7) user=> (map (partial + 2) [1 2 3 4 5]) (3 4 5 6 7) user=> I know that the answer is likely to be "it depends." I am just interested in whether one is more idiomatic/functional than the other, performance issues that one approach may have that the other one doesn't, etc. Thanks in advance, PS: I'm even tempted to say that if one could do (map (+ 2) [1 2 3 4 5]) it would look even better :) U -- 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
