00124.rb

bearings = {
  north: ->(x,y) { [x+1, y] },
  east:  ->(x,y) { [x, y+1] },
  south: ->(x,y) { [x-1, y] },
  west:  ->(x,y) { [x, y-1] }
}

bot = ->(x, y, bearing) do
  {
    coords: [x, y],
    bearing: bearing,
    step: -> do
      bot.(*bearings[bearing].(x,y), bearing)
    end
  }
end

b = bot.(5, 5, :east) # => {:coords=>[5, 5], :bearing=>:east, :step=>#<Proc:0x00000001cffe58@-:12 (lambda)>}
b = b[:step].() # => {:coords=>[5, 6], :bearing=>:east, :step=>#<Proc:0x00000001cff7f0@-:12 (lambda)>}
b = b[:step].() # => {:coords=>[5, 7], :bearing=>:east, :step=>#<Proc:0x00000001cff250@-:12 (lambda)>}