The simplest building block for Life

genesis.es6

// This two-dimensional Turing Machine starts in the upper-left-hand corner of the
// tableau and counts the number of 1s surrounding a center cell, and
// then determines whether the centre cell should be born, survive, or die.

const life = [
  ['start', 0, 'ul-zero', Move(RIGHT)],
  ['start', 1, 'ul-one', Move(RIGHT)],

  ['ul-zero', 1, 'uc-one', Move(RIGHT)],
  ['ul-zero', 0, 'uc-zero', Move(RIGHT)],
  ['uc-zero', 0, 'ur-zero', Move(DOWN)],
  ['uc-zero', 1, 'ur-one', Move(DOWN)],
  ['ur-zero', 0, 'mr-zero', Move(DOWN)],
  ['ur-zero', 1, 'mr-one', Move(DOWN)],
  ['mr-zero', 0, 'lr-zero', Move(LEFT)],
  ['mr-zero', 1, 'lr-one', Move(LEFT)],
  ['lr-zero', 0, 'lc-zero', Move(LEFT)],
  ['lr-zero', 1, 'lc-one', Move(LEFT)],
  ['lc-zero', 0, 'll-zero', Move(UP)],
  ['lc-zero', 1, 'll-one', Move(UP)],
  ['ll-zero', 0, 'zero', Move(RIGHT)],
  ['ll-zero', 1, 'one', Move(RIGHT)],

  ['ul-one', 0, 'uc-one', Move(RIGHT)],
  ['ul-one', 1, 'uc-two', Move(RIGHT)],
  ['uc-one', 0, 'ur-one', Move(DOWN)],
  ['uc-one', 1, 'ur-two', Move(DOWN)],
  ['ur-one', 0, 'mr-one', Move(DOWN)],
  ['ur-one', 1, 'mr-two', Move(DOWN)],
  ['mr-one', 0, 'lr-one', Move(LEFT)],
  ['mr-one', 1, 'lr-two', Move(LEFT)],
  ['lr-one', 0, 'lc-one', Move(LEFT)],
  ['lr-one', 1, 'lc-two', Move(LEFT)],
  ['lc-one', 0, 'll-one', Move(UP)],
  ['lc-one', 1, 'll-two', Move(UP)],
  ['ll-one', 0, 'one', Move(RIGHT)],
  ['ll-one', 1, 'two', Move(RIGHT)],

  ['uc-two', 0, 'ur-two', Move(DOWN)],
  ['uc-two', 1, 'ur-three', Move(DOWN)],
  ['ur-two', 0, 'mr-two', Move(DOWN)],
  ['ur-two', 1, 'mr-three', Move(DOWN)],
  ['mr-two', 0, 'lr-two', Move(LEFT)],
  ['mr-two', 1, 'lr-three', Move(LEFT)],
  ['lr-two', 0, 'lc-two', Move(LEFT)],
  ['lr-two', 1, 'lc-three', Move(LEFT)],
  ['lc-two', 0, 'll-two', Move(UP)],
  ['lc-two', 1, 'll-three', Move(UP)],
  ['ll-two', 0, 'two', Move(RIGHT)],
  ['ll-two', 1, 'three', Move(RIGHT)],

  ['ur-three', 0, 'mr-three', Move(DOWN)],
  ['ur-three', 1, 'too-many', Move(LEFT)], // short circuit
  ['mr-three', 0, 'lr-three', Move(LEFT)],
  ['mr-three', 1, 'too-many', Move(LEFT), Move(UP)], // short circuit
  ['lr-three', 0, 'lc-three', Move(LEFT)],
  ['lr-three', 1, 'too-many', Move(UP)], // short circuit
  ['lc-three', 0, 'll-three', Move(UP)],
  ['lc-three', 1, 'too-many', Move(UP), Move(RIGHT)], // short circuit
  ['ll-three', 0, 'three', Move(RIGHT)],
  ['ll-three', 1, 'too-many', Move(RIGHT)],

  ['zero', 0, HALT, Write(0)],
  ['zero', 1, HALT, Write(0)],
  ['one', 0, HALT, Write(0)],
  ['one', 1, HALT, Write(0)],
  ['two', 0, HALT, Write(0)],
  ['two', 1, HALT, Write(1)],
  ['three', 0, HALT, Write(1)],
  ['three', 1, HALT, Write(1)],
  ['too-many', 0, HALT, Write(0)],
  ['too-many', 1, HALT, Write(0)]
];