While lambdas and streams (along with default methods, or traits) are certainly ...

on Feb 9, 2014

[deleted]

pron · on Feb 9, 2014

That was introduced back in Java 7.

simulacrum · on Feb 9, 2014

try-with-resources actually came in with Java 7

eweise · on Feb 9, 2014

Isn't that what the loan pattern does and is easily accomplished with lambdas? Doesn't seem like a special case that needs to be supported by changing the language.

javafu2 · on Feb 9, 2014

You can not modified a variable declared in the outer scope inside a lambda.

int a = 0; list.forEach(element -> { a++; // no way ! });

That's why it's a lambda and not a closure BTW.

AYBABTME · on Feb 10, 2014

Can always make:

   final int[] a = {0};
   list.forEach(element -> { a[0]++; });

mbell · on Feb 10, 2014

It's still a closure, just a closure with immutable capture, just like Python. Also like Python, you can get around it by boxing the variable you would like to modify (or using nonlocal in Python 3).

IMO the lack of exception transparency is going to be more of an issue with Java's lambdas.

javafu2 · on Feb 10, 2014

For most of the used programming languages, a lambda captures values (like in Java or Python), and closure capture variables or scope (like in Scheme or Ruby), hence the name, a closure close (bind) the free variable of the closure to the ones of the lexical scope.

The lack of checked exception transparency is for me something that goes in the right direction. The hidden message is 'Use checked exception only for IOs and please don't create your own exceptions, use already existing ones !'

mbell · on Feb 10, 2014

A lambda doesn't capture anything, it's just an anonymous function. A lambda can be a closure, but it doesn't have to be.

Closures come in two primary flavors, bind by value or bind by reference. Some languages implement only one of these, some implement both, some bind in completely different ways (e.g. lazy binding in Haskell).