Simple automata

Automata.fs

// http://atlas.wolfram.com/01/01/
let on = 1uy
let off = 0uy

let print xs =
    for x in xs do if x = on then printf "X" else printf " "
    printf "\n"

let rule0 p _ r = (p + r) % 2uy
let rule51 _ q _ = (on + q) % 2uy
let rule57 p q r = (on + q + r + p*r) % 2uy
let rule62 p q r = (p + q + r + p*r + q*r + p*r*q) % 2uy
let rule105 p q r = (on + p + q + r) % 2uy
let rule129 p q r = (on + p + q + p*q + r + p*r + q*r) % 2uy
let rule205 p _ r = (p + r - p*r) % 2uy
let rule225 p q r = (on + p + q + r + q * r) % 2uy

let advance src (dst: byte array) =
    for i in 1..(Array.length src - 2) do
        dst[i] <- rule0 src[i-1] src[i] src[i+1]

let width = 180
let xs = Array.init width (fun i -> if i = width/2 then on else off)
let ys = Array.zeroCreate<byte> width

for i in 0..100 do
    if i % 2 = 0 then
        advance xs ys
        print xs
    else
        advance ys xs
        print ys

Automata.go

package main

import "fmt"

var on byte = 1
var off byte = 0

func print(xs []byte) {
	for _, x := range xs {
		if x == on {
			fmt.Print("#")
		} else {
			fmt.Print(" ")
		}
	}
	fmt.Println()
}

func advance(xs []byte) {
	cp := make([]byte, len(xs))
	copy(cp, xs)
	for i := 1; i < len(xs)-1; i++ {
		xs[i] = (cp[i-1] + cp[i+1]) % 2
	}
}

func main() {
	width := 100
	iterations := 1000
	xs := make([]byte, width)

	for i := 0; i < width; i++ {
		xs[i] = off
	}
	xs[width/2] = on

	for i := 0; i < iterations; i++ {
		print(xs)
		advance(xs)
	}
}

Automata.nim

import sequtils
import random

const
  on = 1
  off = 0
  width = 100
  iterations = 100

proc advance(xs: seq[int]): seq[int] =
  result = xs
  for i in 1..<xs.len-1:
    result[i] = (xs[i-1] + xs[i+1]) mod 2

proc print(xs: seq[int]) =
  for x in xs:
    if x == off: stdout.write(" ")
    else: stdout.write("#")
  echo ""

proc main() =
  # Start off with one in the middle
  var xs = newSeqWith(width, off)
  xs[width div 2] = on

  # Or start off random
  #var xs = newSeqWith(width, rand(1))

  for i in 0..<iterations:
    xs.print
    xs = advance(xs)


main()