Is there any requirement for Comparable to be in elixir core? Could this be implemented as a library?
On Sun, Aug 7, 2016, 1:13 PM Michał Muskała <[email protected]> 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/836EAED5-CCA7-4144-A14B-E9637140A55C%40muskala.eu > . > For more options, visit https://groups.google.com/d/optout. > -- 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/CAOMhEnzxu-trXoDJpm8XX0jcWw0BOvMg2fWgwOBZHLKOTzeDYQ%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
