4 ms·

Dunno about python (but then again it's a dynamic language...), and it's been an endless discussion for c++ AFAIK. Other than that it's actually rather common

Dunno about python (but then again it's a dynamic language...), and it's been an endless discussion for c++ AFAIK. Other than that it's actually rather common in statically typed languages (except Go ;P). From the top of my head e.g. Java, C#, Typescript, Kotlin, Rust, Haskell all offer constraints for generics.

pjmlp 9y ago
Add CLU, Eiffel, BETA, Sather, ML to that list. :)
masklinn 9y ago
I think your comment is a bit… not sure what the word is, under-appreciating the feature? Over-selling some languages? Because AFAIK Java (or C#?) does not have constrained interface conformance, it only has bounds on functions (which Swift already had). That is you can say static <T extends Comparable<? super T>> void sort(MyList<T> list) such that you can only sort lists of comparables, but you can't say class MyList implements Comparable<T extends Comparable<? super T>> such that MyList implements comparable IIF its items are comparable.
- dahauns 9y ago
  Agh, yes. I already regret putting Java in that list with its wonky implementation. :) But it certainly works with others, e.g. something like this: public class SortedList<T> : ICollection<T>,IEnumerable<T> where T : IComparable<T>
  - masklinn 9y ago
    Is that C#? So it does have optional interface implementation? TIL.
    - dahauns 9y ago
      Huh? I'm not sure where you're getting at.
      - masklinn 9y ago
        I'm only asking if the snippet you posted is C# or something else, and noting that if it's C# I have learned something new about the language. Except now that I look at it more specifically, it looks like a bound on the class's generic parameter rather than a condition on the interface implementation? As in you're defining a SortedList class which implements ICollection and IEnumerable but requires T:IComparable, not defining a SortedList class which implements IEnumerable if T is IComparable. And if that reading is correct, Java can do it just fine: class SortedList<T extends Comparable<T>> implements Collection<T>, Iterable<T> however it's got nothing to do with conditional conformance.

pjmlp 9y ago

Add CLU, Eiffel, BETA, Sather, ML to that list. :)

masklinn 9y ago

I think your comment is a bit… not sure what the word is, under-appreciating the feature? Over-selling some languages? Because AFAIK Java (or C#?) does not have constrained interface conformance, it only has bounds on functions (which Swift already had). That is you can say static <T extends Comparable<? super T>> void sort(MyList<T> list) such that you can only sort lists of comparables, but you can't say class MyList implements Comparable<T extends Comparable<? super T>> such that MyList implements comparable IIF its items are comparable.

dahauns 9y ago
Agh, yes. I already regret putting Java in that list with its wonky implementation. :) But it certainly works with others, e.g. something like this: public class SortedList<T> : ICollection<T>,IEnumerable<T> where T : IComparable<T>
- masklinn 9y ago
  Is that C#? So it does have optional interface implementation? TIL.
  - dahauns 9y ago
    Huh? I'm not sure where you're getting at.
    - masklinn 9y ago
      I'm only asking if the snippet you posted is C# or something else, and noting that if it's C# I have learned something new about the language. Except now that I look at it more specifically, it looks like a bound on the class's generic parameter rather than a condition on the interface implementation? As in you're defining a SortedList class which implements ICollection and IEnumerable but requires T:IComparable, not defining a SortedList class which implements IEnumerable if T is IComparable. And if that reading is correct, Java can do it just fine: class SortedList<T extends Comparable<T>> implements Collection<T>, Iterable<T> however it's got nothing to do with conditional conformance.