I can't speak for real-world speed, but algorithms with similar asymptotic complexity exist that work with immutable data. The hash map is not the only possible map implementation. Example from Haskell: http://hackage.haskell.org/package/containers-0.5.10.2/docs/Data-Map-Strict.html
On Wed, Apr 19, 2017 at 3:33 AM Val <delepl...@gmail.com> wrote: > That's interesting, though quite different from the map implementation > we're used to. Do you know (in any language) such an implementation, and > would it really be as fast? Computing hash, accessing some bucket, and > dealing with collisions seem unavoidable. But I have no idea of the extra > cost of dealing with a "versioned" immutable map, where each new version is > not overwriting the previous one. > > > On Wednesday, April 19, 2017 at 4:12:20 AM UTC+2, Matt Harden wrote: > >> It seems to me the equivalent of append for maps is merge, which would be >> a very useful operation to have in its own right. A useful design for map >> could have been an immutable structure supporting literals, merge, lookup >> and delete operations, where all except lookup would return a new map >> value. The obvious zero value would be an empty map. This can be made >> efficient by sharing underlying data which would be safe since the map was >> immutable. >> >> On Tue, Apr 18, 2017 at 7:59 AM Tad Vizbaras <eta...@gmail.com> wrote: >> > Thank you for detailed explanation. >>> >>> I find myself never using "var a map[int]int" or similar var like map. >>> Maybe just my limited understanding. >>> But I am glad we end up with map[int]int instead of *map[int]int. >>> >>> >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "golang-nuts" group. >>> >> To unsubscribe from this group and stop receiving emails from it, send an >>> email to golang-nuts...@googlegroups.com. >> >> >>> For more options, visit https://groups.google.com/d/optout. >>> >> -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
