The difference between nil and false is really handy in some cases and for many people removing nil (or keeping not-nil) values from a seq is not removing falsy values.
I just wanted to point out the issues that may arise from a blind use of (filter identity [...]) ;) On Friday, October 26, 2012 4:36:16 PM UTC+2, Luc wrote: > I avoid making explicit distinctions between false and nil in my code. > In Clojure a falsy value is either nil or false. > > In interop I ensure that null and false when returned in the upper layers > are made consistent (including Boolean objects set to false). > > Too much potential trouble in my opinion to let this slip everywhere in > your > code, it's not semantically coherent with Clojure. > > Luc P. > > > > Be careful with the (filter identity ...) which will also remove > "falses" > > from seqs. > > (filter identity [nil 2 3 nil false true 4]) > > => (2 3 true 4) > > Since (identity false) and (identity nil) returns respectively false and > > nil they are BOTH rejected by filter. > > > > This could do the trick: > > (filter (comp not nit?) [nil 2 3 nil false true 4]) > > => (2 3 false true 4) > > > > On Wednesday, November 17, 2010 2:37:16 AM UTC+1, Luc wrote: > > > > > user=> (time (filter identity [ nil 1 2 nil 4])) > > > "Elapsed time: 0.053219 msecs" > > > (1 2 4) > > > > > > user=> (time (remove nil? [ nil 1 2 nil 4])) > > > "Elapsed time: 0.065092 msecs" > > > (1 2 4) > > > > > > Choose the flavor your prefer... > > > > > > Luc P. > > > > > > Glen Rubin <rubi...@gmail.com <javascript:>> wrote .. > > > > What is the fastest way to remove nils from a sequence? > > > > > > > > I usually use the filter function, but I see there are other > functions > > > > like remove that should also do the trick. > > > > > > > > -- > > > > You received this message because you are subscribed to the Google > > > > Groups "Clojure" group. > > > > To post to this group, send email to > > > > clo...@googlegroups.com<javascript:> > > > > > Note that posts from new members are moderated - please be patient > with > > > your first > > > > post. > > > > To unsubscribe from this group, send email to > > > > clojure+u...@googlegroups.com <javascript:> > > > > For more options, visit this group at > > > > http://groups.google.com/group/clojure?hl=en > > > Luc P. > > > > > > ================ > > > The rabid Muppet > > > > > > > > > > -- > > You received this message because you are subscribed to the Google > > Groups "Clojure" group. > > To post to this group, send email to clo...@googlegroups.com<javascript:> > > Note that posts from new members are moderated - please be patient with > your first post. > > To unsubscribe from this group, send email to > > clojure+u...@googlegroups.com <javascript:> > > For more options, visit this group at > > http://groups.google.com/group/clojure?hl=en > -- > Softaddicts<lprefo...@softaddicts.ca <javascript:>> sent by ibisMail from > my ipad! > -- 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
