An updated Rust 1.x version of Yehuda's Native Rust Extension post here http://blog.skylight.io/bending-the-curve-writing-safe-fast-native-gems-with-rust/

example.rb

require "./points"

p1 = RustPoint::make_point(10, 10) #  => #<Fiddle::Pointer:0x007f8231e56510 ptr=0x0000010b824000 size=0 free=0x00000000000000> 
p2 = RustPoint::make_point(20, 20) #  => #<Fiddle::Pointer:0x007f8231f20970 ptr=0x0000010b824010 size=0 free=0x00000000000000> 

RustPoint::get_distance(p1, p2) # => 14.142135623730951 

points.rb

require "fiddle"
require "fiddle/import"

module RustPoint
	extend Fiddle::Importer

	dlload "./libpoints.dylib"

	extern "Point* make_point(double, double)"
	extern "double get_distance(Point*, Point*)"
end

points.rs

// Compile this in the command like so:
// rustc points.rs --crate-type=dylib

#[derive(Copy, Clone)]
pub struct Point {
    x: f64,
    y: f64
}

struct Line {
    p1: Point,
    p2: Point
}

impl Line {
	pub fn length(&self) -> f64 {
		let xdiff = self.p1.x - self.p2.x;
		let ydiff = self.p1.y - self.p2.y;

		return (xdiff.powi(2) + ydiff.powi(2)).sqrt();
	}
}

#[no_mangle]
pub extern "C" fn make_point(x: f64, y: f64) -> Box<Point>{
	Box::new( Point{x:x, y:y} )
}

#[no_mangle]
pub extern "C" fn get_distance(p1: &Point, p2: &Point) -> f64{
	Line { p1: *p1, p2: *p2}.length()
}