How should I say it... It just didn't look "symmetrical" to me. So, basically, there is a difference between functions returning sequences - depending on if they are lazy or eager. Hmm...
user=> (reverse []) nil user=> (if (reverse []) true false) false user=> (if (seq (reverse [])) true false) false user=> (lazy-seq nil) () user=> (seq (lazy-seq nil)) nil user=> (if (lazy-seq nil) true false) true user=> (if (seq (lazy-seq nil)) true false) false As long as I remember which function is lazy and which one is eager, I should be fine then. Just wanted to really understand it. Thanks, Frantisek On Feb 18, 5:58 pm, Chouser <chou...@gmail.com> wrote: > On Wed, Feb 18, 2009 at 11:46 AM, Frantisek Sodomka <fsodo...@gmail.com> > wrote: > > > What about 'conj'? Documentation says: > > (conj nil item) returns (item). > > > Currently: > > user=> (conj nil 1) > > (1) > > user=> (conj () 1) > > (1) > > Is there something wrong with that? It looks right and like it > matches the docs to me. > > > Idiom "conj nil" is used in 'reverse': (reduce conj nil coll) > > Currently: > > user=> (reverse [1 2]) > > (2 1) > > user=> (reverse [1]) > > (1) > > user=> (reverse []) > > nil > > > It looks that now all sequence functions return () instead of nil. Is > > 'reverse' correct? > > Things that return lazy seqs now return an empty lazy seq, which > prints as (), instead of nil. However, 'reverse' is not lazy and > normally returns a PersistentList. I don't know that it'd be more > correct to return an empty PersistentList than to return nil as it > does now. > > --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 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 -~----------~----~----~----~------~----~------~--~---
