Also, even Decimal.compare/2 choses to support this which comforted me with this decision:
iex> Decimal.compare(Decimal.new(2), 1.0) ** (ArgumentError) implicit conversion of 1.0 to Decimal is not allowed. Use Decimal.from_float/1 Le sam. 4 mars 2023 à 18:34, Sabiwara Yukichi <sabiw...@gmail.com> a écrit : > Thank you José for the feedback! > > I considered this point, and although it would be ideal, I decided to > consider this case an acceptable trade-off not to handle it, because: > 1. it would make the implementation much more complex as pointed out > 2. it would remove a lot of potential for optimizations > 3. it might not be such a common huge case, because programs tend to work > with a given type, mixing them is not so common > > I'm a) guarding against number-decimal comparisons and b) handling > semantic decimal-decimal comparisons, which should cover the two main > pitfalls with decimals in my experience: > > iex> max(Decimal.new(2), Decimal.from_float(1.0))#Decimal<1.0> > > iex> Cmp.max(Decimal.new(2), Decimal.from_float(1.0))#Decimal<2> > > iex> Cmp.max(Decimal.new(2), 1.0) > ** (Cmp.TypeError) Failed to compare incompatible types - left: #Decimal<2>, > right: 1.0 > > > Le sam. 4 mars 2023 à 17:00, José Valim <jose.va...@dashbit.co> a écrit : > >> We had discussions in the past and the issue with a Comparable protocol >> is that we need multiple dispatch. For example, we should be able to >> semantically compare "Integer cmp Decimal" and "Decimal cmp Integer" which >> is a more complex problem as it requires defining a scale to compare all of >> them. Then you can add a compare numbers functionality that converts them >> to said scale using a separate protocol. It will still require at least two >> protocol dispatches. >> >> On Sat, Mar 4, 2023 at 7:32 AM Sabiwara Yukichi <sabiw...@gmail.com> >> wrote: >> >>> > It's great that there exists a total order (structural) in >>> Elixir/Erlang, I just wish it wasn't accessible with `<`, `>`, as it is too >>> error prone and is simply never what one wants to do (at least in our app). >>> Elixir 2.0? 😆 >>> >>> (another shameless plug) Your comment motivated me to release this >>> project I was working on: https://github.com/sabiwara/cmp. >>> Feedback welcome :) >>> >>> Le sam. 4 mars 2023 à 01:26, Marc-André Lafortune < >>> marc-an...@marc-andre.ca> a écrit : >>> >>>> It's great that there exists a total order (structural) in >>>> Elixir/Erlang, I just wish it wasn't accessible with `<`, `>`, as it is too >>>> error prone and is simply never what one wants to do (at least in our app). >>>> Elixir 2.0? 😆 >>>> >>>> At work I just recently overloaded them to raise unless both arguments >>>> are `is_number`, and we found bugs where we were comparing Decimals, and >>>> other bugs where we were comparing with `nil`. They are no longer allowed >>>> in guards too. >>>> >>>> On Friday, 3 March 2023 at 09:31:28 UTC-5 william.l...@cargosense.com >>>> wrote: >>>> >>>>> > if I’m remembering `DateTime.compare/2` correctly >>>>> >>>>> Close! The `Module.compare/2` functions return one of `:lt`, `:eq`, or >>>>> `:gt` ("less than", "equal to", "greater than"), similar to what Haskell >>>>> does. You may have been thinking of something like OCaml where `compare` >>>>> returns `-1`, `0`, or `1` resp. >>>>> >>>>> > So Why don't we implicitly sort it so that it can be compared by >>>>> inequality sign(> or <)? >>>>> >>>>> To clarify, functions like `<` *define* the sort order. >>>>> >>>>> Any time you sort a list, you're using a function that compares two >>>>> elements. Even if you call `Enum.sort/1`, you're implicitly using `<=/2` >>>>> as >>>>> the comparison function. If you want some other sort order, e.g. for >>>>> semantic ordering of `DateTime`s, then you must supply your own comparison >>>>> function. >>>>> >>>>> The reason that you can use `<` on structs with `CompareChain` is that >>>>> it uses macros to re-write an expression like >>>>> >>>>> `~D[2023-03-03] < ~D[2023-03-04]` >>>>> >>>>> as >>>>> >>>>> `Date.compare(~D[2023-03-03], ~D[2023-03-04]) == :lt`. >>>>> >>>>> But that doesn't change the behavior of `<` itself. We're basically >>>>> stuck with what `<` and the like do. Though as José points out, that's >>>>> actually a good thing. >>>>> >>>>> (Side note, you actually have to call `compare?(~D[2023-03-03] < >>>>> ~D[2023-03-04], Date)` with `CompareChain` to invoke the re-write. I just >>>>> wanted the example to be more readable.) >>>>> On Friday, March 3, 2023 at 3:27:00 AM UTC-5 José Valim wrote: >>>>> >>>>>> It is also important to note that both kinds of comparisons are >>>>>> important to have in a language. The docs for main discuss this: >>>>>> https://hexdocs.pm/elixir/main/Kernel.html#module-structural-comparison >>>>>> >>>>>> On Fri, Mar 3, 2023 at 7:47 AM Austin Ziegler <halos...@gmail.com> >>>>>> wrote: >>>>>> >>>>>>> In this case, because Elixir is passing the `<` and `>` comparisons >>>>>>> to the underlying BEAM operations and there’s no overloading to say that >>>>>>> `left < right` should mean `DateTime.compare(left, right) < 0` and >>>>>>> `left > >>>>>>> right` should mean `DateTime.compare(left, right) > 0` (if I’m >>>>>>> remembering >>>>>>> `DateTime.compare/2` correctly). >>>>>>> >>>>>>> `CompareChain` does that, but it’s something that gets opted into. >>>>>>> >>>>>>> -a >>>>>>> >>>>>>> On Thu, Mar 2, 2023 at 10:42 PM 최병욱 <cbw...@gmail.com> wrote: >>>>>>> >>>>>>>> So Why don't we implicitly sort it so that it can be compared by >>>>>>>> inequality sign(> or <)? >>>>>>>> >>>>>>>> 2023년 3월 3일 금요일 오전 10시 3분 25초 UTC+9에 william.l...@cargosense.com님이 >>>>>>>> 작성: >>>>>>>> >>>>>>>>> Shameless plug: I wrote a library called `CompareChain` that >>>>>>>>> allows you to use operators like `<` and `>` on structs like >>>>>>>>> `DateTime`. >>>>>>>>> >>>>>>>>> Hexdocs: https://hexdocs.pm/compare_chain/readme.html >>>>>>>>> >>>>>>>>> On Thursday, March 2, 2023 at 10:54:08 AM UTC-5 Jay Rogov wrote: >>>>>>>>> >>>>>>>>>> Because the underlying structure used to represent DateTime is a >>>>>>>>>> struct, which is simply a map under the hood. >>>>>>>>>> Erlang/Elixir uses a rather arbitrary order of keys (e.g. hour -> >>>>>>>>>> year -> day -> minute) when comparing 2 maps which you can't control. >>>>>>>>>> >>>>>>>>>> Thus, you need to have a specific function that would compare >>>>>>>>>> these structs according to implied field order (year -> month -> day >>>>>>>>>> -> >>>>>>>>>> hour -> etc.) >>>>>>>>>> >>>>>>>>>> More: >>>>>>>>>> https://hexdocs.pm/elixir/main/NaiveDateTime.html#module-comparing-naive-date-times >>>>>>>>>> >>>>>>>>>> On Thursday, 2 March 2023 at 4:38:00 pm UTC+1 cbw...@gmail.com >>>>>>>>>> wrote: >>>>>>>>>> >>>>>>>>>>> Can't you compare DateTime with '>' or '<' instead of >>>>>>>>>>> DateTime.compare? >>>>>>>>>>> >>>>>>>>>> -- >>>>>>>> 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 elixir-lang-co...@googlegroups.com. >>>>>>>> To view this discussion on the web visit >>>>>>>> https://groups.google.com/d/msgid/elixir-lang-core/afa3830a-8944-4e12-84cc-d8e28d9fceb0n%40googlegroups.com >>>>>>>> <https://groups.google.com/d/msgid/elixir-lang-core/afa3830a-8944-4e12-84cc-d8e28d9fceb0n%40googlegroups.com?utm_medium=email&utm_source=footer> >>>>>>>> . >>>>>>>> >>>>>>> >>>>>>> >>>>>>> -- >>>>>>> Austin Ziegler • halos...@gmail.com • aus...@halostatue.ca >>>>>>> http://www.halostatue.ca/ • http://twitter.com/halostatue >>>>>>> >>>>>>> -- >>>>>>> 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 elixir-lang-co...@googlegroups.com. >>>>>>> >>>>>> To view this discussion on the web visit >>>>>>> https://groups.google.com/d/msgid/elixir-lang-core/CAJ4ekQuHMtqrAVs-kwCo4NQC7vyWV3O8RpAm3c6tgDoiVa%2B5bw%40mail.gmail.com >>>>>>> <https://groups.google.com/d/msgid/elixir-lang-core/CAJ4ekQuHMtqrAVs-kwCo4NQC7vyWV3O8RpAm3c6tgDoiVa%2B5bw%40mail.gmail.com?utm_medium=email&utm_source=footer> >>>>>>> . >>>>>>> >>>>>> -- >>>> 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 elixir-lang-core+unsubscr...@googlegroups.com. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/elixir-lang-core/c6f42de3-7132-4a8b-b3fa-4e7b0db67ce2n%40googlegroups.com >>>> <https://groups.google.com/d/msgid/elixir-lang-core/c6f42de3-7132-4a8b-b3fa-4e7b0db67ce2n%40googlegroups.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>> -- >>> 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 elixir-lang-core+unsubscr...@googlegroups.com. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/elixir-lang-core/CANnyohaRZY_ZRkQ%2BuOP5oHtOTW%3Dwy6vzSNvPiYXT%3D7HP0M2T-g%40mail.gmail.com >>> <https://groups.google.com/d/msgid/elixir-lang-core/CANnyohaRZY_ZRkQ%2BuOP5oHtOTW%3Dwy6vzSNvPiYXT%3D7HP0M2T-g%40mail.gmail.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- >> 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 elixir-lang-core+unsubscr...@googlegroups.com. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4LvGV9Ph2qFZScYmmuB211Rc2%3DbuNfZFKApk1pXfNU1%2Bg%40mail.gmail.com >> <https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4LvGV9Ph2qFZScYmmuB211Rc2%3DbuNfZFKApk1pXfNU1%2Bg%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> > -- You received this message because you are subscribed to the Google Groups "elixir-lang-core" group. 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