#no-std #typemap

nightly no-std tyght-map

A static type map implementation

7 releases

0.1.1 May 24, 2023
0.1.0 Mar 23, 2023
0.1.0-alpha.4 Mar 22, 2023
0.1.0-alpha.2 Mar 21, 2023
0.1.0-alpha.0 Mar 17, 2023

#793 in Data structures

Download history 66/week @ 2023-03-16 65/week @ 2023-03-23 18/week @ 2023-04-06 1/week @ 2023-04-13 6/week @ 2023-04-20 12/week @ 2023-05-04 3/week @ 2023-05-11 18/week @ 2023-05-18 28/week @ 2023-05-25

61 downloads per month

MIT license

333 lines


CI Crates.io Documentation License: MIT

A static type map implementation.


The tyght-map crate provides a static type map implementation.

A type map is a map where the values are indexed by their types.

The map, [TyghtMap], enjoys the following properties:

  • The size of the map will match the size of its items.
  • No heap allocations, this crate is !#[no_std].
  • Provides both infallible and fallible methods.
  • No unsafe.



# use tyght_map::*;
// Insert some different integer types into the map and check the size
let map = TyghtMap::new()
assert_eq!(std::mem::size_of_val(&map), 12);

// Retrieve the `u32` from the map
let item: &u32 = map.get();
assert_eq!(*item, 3);

// Insert a `String` into the map, then mutate it
let mut map = map.insert("Hey".to_string());
*map.get_mut::<String>() += ", world!";

// Try to get a `u8` from the map
let item = map.try_get::<u8>();
assert_eq!(item, None);

// Remove the `String` from the map
let (item, _map) = map.remove::<String>();


Placing constraints on the S of TyghtMap<S> acts as a constraint on the values it contains.

There are three important marker traits:

The following function cannot be called using a map which does not contain a String and a u32.

# use tyght_map::*;
fn print_string<S>(map: &TyghtMap<S>)
    S: Contains<String>,
    S: Contains<u32>
    let string: &String = map.get();
    let int: &u32 = map.get();
    println!("{string} {int}");


In contrast to other attempts, this implementation does not rely on specialization. It does however rely on a variety of nightly features:

These can be expected to be stabilized, in some form, before specialization.

No runtime deps