I have taken some time to create an experimental module that shows how this might work in practice: https://github.com/Qqwy/elixir_experimental_comparable
I am very interested to hear the things about this you like/dislike. :-) Have a wonderful day, ~Wiebe-Marten/Qqwy On Sunday, August 7, 2016 at 10:13:45 PM UTC+2, Michał Muskała wrote: > > Hello everybody, > > Today I’d like to address one of annoyances of working with elixir - > comparing structs. It’s a problem because of two reasons: > - it’s not widely known that the regular comparison operators do not work > correctly with structs > - there’s no standard way of providing custom comparison function. > This issue is especially apparent in couple libraries, most notably Ecto > (with calendar types), decimal and with the new standard calendar types. > > I propose adding a Kernel.compare/2 function with signature: > compare(term, term) :: :lt | :eq | :gt > > I would propose following properties of the function: > - inlined implementation for built-in types, only for both arguments of > the same type > - for structs the function calls the Comparable.compare/2 protocol > function > - implementation for structs are allowed to return value for two different > types when it makes sense > - the protocol is also implemented for built-in types > - the protocol does not fallback to Any > > I’m convinced this will allow for much easier experience when comparing > structs, even though the VM does not allow to extend the regular comparison > operators. > > Michał. > > -- You received this message because you are subscribed to the Google Groups "elixir-lang-core" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/elixir-lang-core/26a99924-78f6-4e25-8c29-6f03e41d0509%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
