Conway's Game of Life written in Rust

life.rs

extern crate rand;

use std::thread;
use std::time::Duration;
use rand::Rng;

struct Field {
  width: usize,
  height: usize,
  grids: Vec<Vec<bool>>
}

impl Field {
  fn new(width: usize, height: usize) -> Field {
//    let grids = vec![vec![false; height]; width];
    let mut grids = Vec::with_capacity(height);
    for j in 0..height {
      let mut row = Vec::with_capacity(width);
      for i in 0..width {
        row.push(rand::thread_rng().gen());
      }
      grids.push(row);
    }
    Field {
      width: width,
      height: height,
      grids: grids
    }
  }
  fn step(&self) -> Field {
    let mut grids = Vec::with_capacity(self.height);
    for j in 0..self.height {
      let mut row = Vec::with_capacity(self.width);
      for i in 0..self.width {
        let mut count = 0;
        for jj in 0..3 {
          for ii in 0..3 {
            if ii == 1 && jj == 1 { continue; }
            if self.grids[(j+jj+self.height-1)%self.height][(i+ii+self.width-1)%self.width] {
              count += 1;
            }
          }
        }
        row.push((self.grids[j][i] && (count == 2 || count == 3)) || (!self.grids[j][i] && count == 3));
      }
      grids.push(row);
    }
    Field {
      width: self.width,
      height: self.height,
      grids: grids
    }
  }
}

fn main() {
  let mut field = Field::new(24, 16);
  for i in 0..1000 {
    println!("{}[2J", 27 as char);
    for row in &field.grids {
      for grid in row {
        print!("{}", if *grid { "*" } else { "." });
      }
      println!();
    }
    field = field.step();
    thread::sleep(Duration::from_millis(50));
  }
}