Dart does not support instantiating from a generic type parameter. It doesn’t matter if you want to use a named or default constructor (T() also does not work). There is probably a way to do that on the server, where dart:mirrors (reflection) is available (not tried myself yet), but not in Flutter or the browser. … Read more
GHC.Generics is the modern way and it is much faster than SYB. It however exposes a different approach to generic programming to the end user, so I don’t think that it should be thought of as a direct replacement of SYB, though it does solve the same problems. A good example of how those approaches … Read more
A free functor is left adjoint to a forgetful functor. For the adjunction you need to have the isomorphism (natural in x and y): (Free y :~> x) <-> (y :~> Forget x) In what category should this be? The forgetful functor forgets the Arrow instance, so it goes from the category of Arrow instances … Read more
Is it possible? (Without changing the function calls obviously. AKA without a().) Yes. I believe in your case you would do var a = function<T = any>() : T { return null; } Generic defaults were introduced in TS 2.3. Default types for generic type parameters have the following syntax: TypeParameter : BindingIdentifier Constraint? DefaultType? … Read more
You can return any types’ name by using string interpolation: class MyClass<T> { func genericName() -> String { return “\(T.self)” } } You can try it in a playground and it works as expected: var someClass = MyClass<String>() someClass.genericName() // Returns “Swift.String”
The default map key serializer is StdKeySerializer, and it simply does this. String keyStr = (value.getClass() == String.class) ? ((String) value) : value.toString(); jgen.writeFieldName(keyStr); You could make use of the SimpleModule feature, and specify a custom key serializer, using the addKeySerializer method. And here’s how that could be done. import java.io.IOException; import java.util.Date; import java.util.HashMap; … Read more
It means “Rust compiler, infer what type goes into the Vec“. And it is indeed analogous to the unused variable in Python (and in Rust itself), in that it represents a placeholder for a type, like it can represent a placeholder for a variable name. You can find an explanation in The Rust Programming Language … Read more
I have run into the same issue and found this article. In a nutshell you have this options: Make not generic wrapper class containing injected fields, make it to be a field of your class and inject it instead of generic class itself. Inject child non-generic class instead of base class. All annotated with @Inject … Read more
It seems to be a glitch. The Rust-analyzer LSP is able to infer what the type is supposed to be, but for whatever reason the compiler can’t. From what I can tell, this code doesn’t compile on any version of Rust, and cannot be automatically fixed with cargo fix. Interestingly, the compiler does seem to … Read more
As you’ve noted, impl AsRef<User> for User seems a little pointless since you can just do &user. You could do impl AsRef<String> for User or impl AsRef<u8> for User as alternatives to &user.email and &user.age but those examples are probably misuses of the trait. What does it mean to be able to convert a User … Read more