I have missed most of the discussion but it feels strange that a function in Kernel, Kernel.compare/2, results in calls to a protocol. For me Kernel feels like being at the very base and should not call anything outside it, irrespective of whether it is part of elixir core or not.
Robert On Sunday, 7 August 2016 22:13:45 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/84475239-f29b-4dd5-a903-810fab453489%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
