iflet - a Rust macro to avoid nested if let

if let is an extremely nice concept in Rust. You can use it in place of a pattern match for readability, like in this extremely contrived example below:

```rust fn div(num: i32, denom: i32) -> Option { if denom == 0 { return Some(num / denom);

None

}

fn main() { if let Some(x) = div(6, 2) { assert_eq!(x, 3); } } ```

However, you can't use if let to match multiple clauses or with additional if guards (like in match patterns). iflet provides a macro that lets you do just that:

```rust

[macro_use]

extern crate iflet;

[macro_use]

extern crate serde_json;

use serde_json::Value::{Object, Array};

fn main() { let value = json!({ "numbers": [ 1, 2, 4, 9, 16, 25 ] });

if_chain!([let Object(ref map) => value,
           let Some(&Array(ref vec)) if !vec.is_empty() => map.get("numbers")] {
    println!("there are {} numbers stored in the object", vec.len());
} else {
    println!("there are no numbers stored in the object");
});

} ```