scalar_map

map for scalar types.

let num: Option<i32> = Some(42);
assert_eq!(num.map(|x| 42 - x), Some(0));

let num: i32 = 42;
assert_eq!(num.map(|x| 42 - x), 0);

let num: Option<i32> = Some(42);
assert_eq!(num.and_then(Option::Some), Some(0));

let num: i32 = 42;
assert_eq!(num.and_then(Option::Some), Some(0));

What does it solve

• You can still keep map and and_then intact even if Option is refactored out.

• You want

  x.map(Mutex::new).map(Arc::new)
  

  ...instead of

  Arc::new(Mutex::new(x))
  

Custom struct

Deriving

# Run this to add the `derive` feature
cargo add scalar_map --features derive

#[derive(Debug, PartialEq, ScalarMap)]
struct MyNum(i32);

let num = MyNum(42);
assert_eq!(num.map(|x| 42 - x.0).map(MyNum), MyNum(0));

Without deriving

#[derive(Debug, PartialEq)]
struct MyNum(i32);
impl ScalarMapExt for MyNum {}

let num = MyNum(42);
assert_eq!(num.map(|x| 42 - x.0).map(MyNum), MyNum(0));