How do I create a map from a list in a functional way?

Question

In Scala, there is a method named toMap that works on any list of tuples and converts it to a map where the key is the first item on the tuple and the value is

Answer 1

Since it wasnt already mentioned, here is a single line (albeit long) method:

use std::collections::HashMap;

fn main() {
   let m: HashMap<&str, u16> = [("year", 2019), ("month", 12)].iter().cloned().collect();
   println!("{:?}", m);
}

Or you can do a Trait:

use std::collections::HashMap;

trait Hash {
   fn to_map(&self) -> HashMap<&str, u16>;
}

impl Hash for [(&str, u16)] {
   fn to_map(&self) -> HashMap<&str, u16> {
      self.iter().cloned().collect()
   }
}

fn main() {
   let m = [("year", 2019), ("month", 12)].to_map();
   println!("{:?}", m)
}

https://doc.rust-lang.org/std/collections/struct.HashMap.html#examples