What are the benefits of Java's types erasure?

Question

I read a tweet today that said:

It\'s funny when Java users complain about type erasure, which is the only thing Java got right, while ignoring all th

Answer 1

The one thing I don't see considered here at all is that OOP's runtime polymorphism is fundamentally dependent on the reification of types at runtime. When a language whose backbone is held in place by refied types introduces a major extension to its type system and bases it on type erasure, cognitive dissonance is the inevitable outcome. This is precisely what happened to the Java community; it is why type erasure has attracted so much controversy, and ultimately why there are plans to undo it in a future release of Java. Finding something funny in that complaint of Java users betrays either an honest misunderstanding of the spirit of Java, or a consciously deprecating joke.

The claim "erasure is the only thing Java got right" implies the claim that "all languages based on dynamic dispatch against the runtime type of function argument are fundamentally flawed". Although certainly a legitimate claim on its own, and one which can even be considered as valid criticism of all OOP languages including Java, it cannot lodge itself as a pivotal point from which to evaluate and criticise features within the context of Java, where runtime polymorphism is axiomatic.

In summary, while one may validly state "type erasure is the way to go in language design", positions supporting type erasure within Java are misplaced simply because it is much, much too late for that and had already been so even at the historical moment when Oak was embraced by Sun and renamed to Java.

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As to whether static typing itself is the proper direction in the design of programming languages, this fits into a much wider philosophical context of what we think constitutes the activity of programming. One school of thought, clearly deriving from the classical tradition of mathematics, sees programs as instances of one mathematical concept or other (propositions, functions, etc.), but there is an entirely different class of approaches, which see programming as a way to talk to the machine and explain what we want from it. In this view the program is a dynamic, organically growing entity, a dramatic opposite of the carefully erected aedifice of a statically typed program.

It would seem natural to regard the dynamic languages as being a step in that direction: the consistency of the program emerges from the bottom up, with no a priori constrants which would impose it in a top-down manner. This paradigm can be seen as a step towards modeling the process whereby we, the humans, become what we are through development and learning.