Lambdas & Closures

Lambdas and closures.

C++

Rust

Java


vector<int> vals = {-1, -2, -3, 1, 2, 3, 0};
int p = 2;

sort(vals.begin(),
     vals.end(),
     [p](int a, int b) {
        return pow(a, p) < pow(b, p);
        });




let mut vals = [-1, -2, -3, 1, 2, 3, 0];
let p = 2;

vals.sort_by(|a :&isize, b :&isize|
                a.pow(p).cmp(&b.pow(p)));




List<Integer> vals = Arrays.asList(-1, -2, -3, 0, 1, 2, 3);
int p = 2;

Collections.sort(vals, (a, b) -> 
        Integer.compare(Math.pow(a, p), Math.pow(b, p)));


Lambdas (and closures) were added to C++ in C++11 and to Java in Java 8. Rust has always had them.

In C++ you are required to specify the values that are captured by the lambda. In Java and Rust the compiler handles capturing without specifying the values.