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Core Intermediate

09 Closures

A closure is a small anonymous function that can capture variables from its surroundings. Return one from a function, then accept one as an argument -- the two shapes iterator chains are built from.

Step 1 / 2

Make make_adder return a closure that adds n to its argument.

Hints

Closure syntax: |x| x + n -- arguments between pipes, body after.
The closure outlives make_adder, so it must own n: write move |x| x + n.

09_closures.rs

// return a closure that adds n to its argument
fn make_adder(n: i32) -> impl Fn(i32) -> i32 {
    todo!()
}

// return a closure that adds n to its argument
fn make_adder(n: i32) -> impl Fn(i32) -> i32 {
    todo!()
}

Reset to starterCompiled in a sandbox; hidden checks must pass.

Reveal solution

fn make_adder(n: i32) -> impl Fn(i32) -> i32 {
    move |x| x + n
}

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09 Closures