On Wed, Feb 18, 2009 at 8:02 PM, Rich Hickey <richhic...@gmail.com> wrote: > > > > On Feb 18, 12:20 pm, Frantisek Sodomka <fsodo...@gmail.com> wrote: >> 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. >> > > It shouldn't be that subtle. Sequence functions shouldn't return nil > unless they are variants of seq/next. I've fixed reverse and sort to > return () when passed empty colls - SVN 1294. > > Rich. >
Wouldn't it make more sense to to return an empty version of the same collection type? That way the following would work more like someone would expect. (conj (rest [1]) 2) -> [2] instead of (2) --Stefan --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
