This was inspired by #8511 , where I commented what I could see as a potential solution to the same problem. I figured I could outline it here and see what others from the community think about this idea. The problem Crystal has a pretty strict type system, which is awesome. Unfortunately, the stric…

This is a great idea, and I’d like this to happen. The problem is that interfaces are typed, but in the rest of the language it’s not mandatory to type your methods. So a user will create a type with def to_i without an explicit return type, and the compiler won’t consider that type. For example B…

Can’t the same thing happen that happens when duck typing? The compiler is able to determine the return value of a type at compile time, so is there any reason it couldn’t do the same with abstract as well as this potential interface type?

[image] watzon: The compiler is able to determine the return value of a type at compile time Only when the method is called. Maybe it’s possible, but to do this it also needs to be done through virtual dispatch with virtual tables, and boxing might need to happen… it’s really hard to do this…

2.0 would be fair, as long as it’s on the road map. I know a lot of the ground work is there, but I also know it will require a decent amount of work to make happen. It’s good to see the idea has the support of some core team members though.

Crystal has interfaces in Java sense: [image] Crystal has Interfaces in Java sense Crystal Contrib During discussion we’ve discovered Crystal has interfaces in Java sense. Module can have abstract method, and its inclusion demands implementation: https://play.crystal-lan…

Proposal: Interfaces for more generic code

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funny-falcon November 10, 2022, 8:25am 6

Crystal has interfaces in Java sense:

Topic		Replies	Views
Crystal has Interfaces in Java sense Crystal Contrib	5	1130	November 10, 2022
[RFC] Standardized Abstractions Crystal Contrib	29	2510	July 14, 2023
Structural typing vs interfaces Help & Support	7	1207	May 11, 2020
Module as a type? Help & Support	3	429	January 3, 2022
Typing and testing Help & Support	9	714	September 7, 2023

Proposal: Interfaces for more generic code

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