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by takikawa 4656 days ago
Typed Racket definitely doesn't add a "Java-style static typing" system at all. Its type system is quite specifically designed to accommodate the kinds of programming idioms you find in Racket programs (via occurrence typing, function intersection types, and so on), and comes with local type inference.
1 comments
asdasf 4656 days ago
I don't use racket obviously, but looking through the docs on typed racket it certainly looks like it adds java-style static typing. Having crappy partial type inference doesn't make the type system powerful or expressive, C# has that too and it certainly falls into the java-style type system camp.
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takikawa 4656 days ago
> but looking through the docs on typed racket it certainly looks like it adds java-style static typing

It's unclear what you mean by "Java-style static typing" then, because the Java type system and Typed Racket's type system are completely different.

One actually has local type inference (which is not "crappy" type inference necessarily; HM-style type inference is notoriously brittle), the other doesn't. One has nominal class types, the other has no class types (yet). One has intersection types, occurrence typing, "true" union types, and so on, while the other has none of those. One has bounded polymorphism, the other has System F-like polymorphism. One of them has variable-arity polymorphism, while the other doesn't. The list goes on.

In fact, aside from being explicitly typed, there are few similarities.

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asdasf 4655 days ago
>One actually has local type inference

Which is totally orthogonal to the power and expressiveness of the type system. I specifically gave an example that C# also has crappy limited type inference too, and is still java-style static typing.

>HM-style type inference is notoriously brittle

Yeah, obviously no languages could possibly exist that use it with no problems.

>One has nominal class types, the other has no class types (yet)

What does being OO have to do with anything? I am talking about the expressiveness of the type system. The amount of things you can express in the type system.

>One has intersection types, occurrence typing, "true" union types

So racket has a partial implementation of ADTs? And that's it? Ok, you win, racket has java + 0.1 level of static typing, hooray! The point is, using static typing in racket gets you virtually nothing, because it is such a primitive type system. Go use ML or haskell and then compare it to typed racket.

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