Comment by arturventura | Hacker News Reader

Comment by arturventura | Hacker News Reader

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I had to implement a Java REPL like this one in school.

My experience of using it is that tells me that without a undefined type keyword it becomes very boring to use. Each time you have to define a variable you have to write all type info:

    Map<String,String> foo = new HashMap<>();

If java had a inferred type declaration, like Golang, Swift, Scala, etc. This would be much simpler:

    var foo = new HashMap<String,String>();

But from what I think there is nothing like that on Java's roadmap. In fact, I think it was proposed and rejected in the past.

I get why that would be nice, but it feels kinda wrong for what Java is[0]. That's why if I need to quickly bang out or test something I use my Scala REPL.

[0] - http://programmers.stackexchange.com/a/184183/7007

What's wrong with simply: Object foo = ...

Not quite var, and it would require the interpreter to do a little bit more work when invoking methods to avoid the necessary downcasting.

Because you're sacrificing consistancy and type safety for object to avoid increasing the syntax which feels like optimising for the wrong metric.

It's a REPL! It's for debugging. If you're not optimizing for ease of use, you're optimizing for the wrong metric.

You could also just add support for the "var x =" notation into the REPL as a preprocessing step that translates it to the appropriate typed representation.

Java can do the reverse, infer an implementations generic types from the declaration.

Map<String, String> foo = new HashMap<>();

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