Well it does not break referential transparency if both equalities (for input values and for results) are of a same kind. You would have to compare inputs by value and outputs by identity, if you want to percieve an inconsistency.
JW On Saturday, February 8, 2014 6:49:39 PM UTC+1, Andy Fingerhut wrote: > > This might be too detailed a point, but I wanted to mention that while you > will always get the same order for the same collection (same as determined > by identical?, or Java ==, i.e. it is the same object in memory), you are > *not* guaranteed to get the same order for collections of the same type > that are equal to each other as determined by Clojure = or Java .equals. > In particular, if two values have the same hash value, then if they are > used as a set in a Clojure PersistentHashSet or a key in a > PersistentHashKey, they are put into a linear list in a hash bucket for > that hash value, and their order in that list can be different in different > sets/maps, and the order that (seq ...) returns on those sets/maps will be > different. > > I am not certain, but this might violate referential transparency > (replacing a value that is equals for another value in an expression will > always give you an equal result). > > I was curious whether anyone knows whether Haskell has hash-based data > structures like this, and do they somehow guarantee referential > transparency? Perhaps by requiring the items to be sortable? > > Andy > > > On Sat, Feb 8, 2014 at 8:19 AM, Jozef Wagner <jozef....@gmail.com<javascript:> > > wrote: > >> Every persistent collection in Clojure supports conversion to the >> sequence of items. This is clearly documented in the official docs and >> there is no surprise here. >> >> The order or items in the resulting sequence is dependent on the >> collection type. As the conversion to the sequence is a referentially >> transparent function, you will always get the same order for the same >> collection. >> >> JW >> >> On Saturday, February 8, 2014 4:59:47 PM UTC+1, Andy C wrote: >> >>> On Sat, Feb 8, 2014 at 12:06 AM, Sean Corfield <se...@corfield.org>wrote: >>> >>>> But you're misunderstanding what map does: it converts its collection >>>> arguments to _sequences_ and then it processes those sequences. Map >>>> doesn't operate on sets, or vectors, or maps, only on sequences. >>>> >>> >>> Your assertion that I "am misunderstanding something" is wrong. >>> >>> One cannot convert amorphic set into linear sequence without assuming >>> certain order. And as with every assumption, it always comes with some less >>> or more pragmatic but arbitrary decision which might change over time and >>> ruin peoples programs. >>> >>> I would expect Clojure to throw "IllegalArgumentException Don't know how >>> to create ISeq from: clojure.lang.PersistentHashSet" or document it >>> well in map somewhere. >>> >>> >>> "Perfection is the enemy of the good." >>>> >>> >>> Now judging by your sig, it all does not surprise me LOL >>> >>> >>> >>> -- >> 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 >> --- >> You received this message because you are subscribed to the Google Groups >> "Clojure" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to clojure+u...@googlegroups.com <javascript:>. >> For more options, visit https://groups.google.com/groups/opt_out. >> > > -- 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 unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
