Why can't the var keyword in Java be assigned a lambda expression?

Question

It is allowed to assign var in Java 10 with a string like:

var foo = \"boo\";

While it is not allowed to assign it with a lambda e

Answer 1

To everyone who is saying this is impossible, undesired, or unwanted, I just want to point out that Scala can infer the lambda's type by specifying only the argument type:

val predicateVar = (apple: Apple) => apple.getColor().equals("red")

And in Haskell, because getColor would be a standalone function not attached to an object, and because it does full Hindley-Milner inference, you don't need to specify even the argument type:

predicateVar = \apple -> getColor apple == "red"

This is extraordinarily handy, because it's not the simple types that are annoying for programmers to explicitly specify, it's the more complex ones.

In other words, it's not a feature in Java 10. It's a limitation of their implementation and previous design choices.