#collection #literals #iterator #macro


vec! for everything: easily make literals of any collection!

1 unstable release

0.1.0 Mar 28, 2023

#2698 in Rust patterns

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A macro to create collection literals for any type! Think of vec!, but for any collection type!

Internally, this just uses the Iterator::collect() method. Since collect is powered by FromIterator, implement it to use this macro for your own types!


Basic use, inferring the type of the collection

use collect_all::collect;
use std::collections::HashSet;

let hashset: HashSet<i32> = collect![1, 2, 3];
assert_eq!(HashSet::from_iter([1, 2, 3]), hashset);

Specifying the type in the macro invocation

use collect_all::collect;
use std::collections::HashMap;

let hashmap = collect![HashMap<&str, u8>: ("one", 1), ("two", 2)];
assert_eq!(HashMap::from_iter([("one", 1), ("two", 2)]), hashmap);

Creating with a given capacity

use collect_all::collect;
use std::path::PathBuf;

let pathbuf = collect![PathBuf: "path", "to", "file"; 10];
assert_eq!(PathBuf::from("path/to/file"), pathbuf);
assert!(pathbuf.capacity() >= 10);

Note that this relies on a few things that are not strictly guaranteed for a given collection:

  1. with_capacity is a method of the target type (for example, see Vec::with_capacity)
  2. The target type implements Extend


This crate is licensed under the MIT license.

No runtime deps