Empty list type
Can somebody explain the rationale behind this?: (isa? (type '(:foo :bar)) clojure.lang.PersistentList) = true (isa? (type ()) clojure.lang.PersistentList) = false (isa? (type (list)) clojure.lang.PersistentList) = false -- 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: Empty list type
(isa? (type '(:foo :bar)) clojure.lang.IPersistentList) = true (isa? (type ()) clojure.lang.IPersistentList) = true (isa? (type (list)) clojure.lang.IPersistentList) = true 2011/11/1 Sebastián Galkin paras...@gmail.com Can somebody explain the rationale behind this?: (isa? (type '(:foo :bar)) clojure.lang.PersistentList) = true (isa? (type ()) clojure.lang.PersistentList) = false (isa? (type (list)) clojure.lang.PersistentList) = false -- 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 -- 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: Empty list type
On Tue, Nov 1, 2011 at 7:33 PM, David Nolen dnolen.li...@gmail.com wrote: (isa? (type '(:foo :bar)) clojure.lang.IPersistentList) = true (isa? (type ()) clojure.lang.IPersistentList) = true (isa? (type (list)) clojure.lang.IPersistentList) = true (type ()) ;= clojure.lang.PersistentList$EmptyList EmptyList is an inner class in PesistentList, and is not directly derived from PersistentList. Though, as David shows, both PersistentList and PersistentList$EmptyList implement the interface IPersistentList. 2011/11/1 Sebastián Galkin paras...@gmail.com Can somebody explain the rationale behind this?: (isa? (type '(:foo :bar)) clojure.lang.PersistentList) = true (isa? (type ()) clojure.lang.PersistentList) = false (isa? (type (list)) clojure.lang.PersistentList) = false -- 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 -- 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 -- 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: Empty list type
On Tuesday, November 1, 2011 9:33:31 PM UTC-2, David Nolen wrote: (isa? (type '(:foo :bar)) clojure.lang.IPersistentList) = true (isa? (type ()) clojure.lang.IPersistentList) = true (isa? (type (list)) clojure.lang.IPersistentList) = true oh that's right Thank you! -- 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: Empty list type
2011/11/1 Sebastián Galkin paras...@gmail.com: On Tuesday, November 1, 2011 9:33:31 PM UTC-2, David Nolen wrote: (isa? (type '(:foo :bar)) clojure.lang.IPersistentList) = true (isa? (type ()) clojure.lang.IPersistentList) = true (isa? (type (list)) clojure.lang.IPersistentList) = true oh that's right There's a larger point here that I think David was making. It is important not to rely on the concrete type of anything, but instead to rely on an interface or protocol that it supports. Choose the right abstraction to allow concrete details to be adjusted without breaking your program. The EmptyList class is a perfect example of an implementation detail that we shouldn't rely on. Nobody promises that it will be there in the future. However, Clojure does promise that '(:foo :bar), () and (list) will all return something for which seq?, list?, coll?, and sequential? will return true, and that () and (list) will return something for which empty? will return true. --Chouser -- 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
