functional pico8

test.lua

function _init()
 my_grid = make_grid(10,10)
 .map(set_wall)
 
 my_grid.each(log)
 
 room = my_grid
 .select(4, 4, 7, 7)
 .map(set_blank)
 
 room.each(log)
 
 state = compose(my_grid, room) 
	state.each(log) 
end

function log(v, x, y)
 print(x..','..y..':'..v)
end
function render(v, x, y)
 pset(x, y, v)
end

function make_grid(width, height)
 local whole={}
 return grid(1,1,width,height,whole)
end

function grid(x1, y1, x2, y2, _grid)
 _grid = either(_grid, {})
 _grid[0] = {}
 x1 = either(x1, 1)
 y1 = either(y1, 1)
 x2 = either(x2, #_grid)
 y2 = either(y2, #_grid[0])
 local with=function(fn)
  for x=x1,x2 do
   _grid[x] = either(_grid[x], {})
   for y=y1,y2 do
    fn(x, y)
   end
  end
 end
 return {
  body=function()
   return _grid
  end,
  select=function(x1, y1, x2, y2)
   return grid(x1, y1, x2, y2, _grid)
  end,
  map=function(fn)
   local tbl={}
   with(function(x,y)
    tbl[x] = either(tbl[x], {})
    tbl[x][y] = fn(_grid[x][y], x ,y)
   end)
   return grid(x1, y1, x2, y2, tbl)
  end,
  each=function(fn)
   with(function(x,y)    
    fn(_grid[x][y], x, y)
   end)
  end
 }
end

function compose(...)
 local arg = {...}
 local t={}
 for a=1,#arg do
  local body = arg[a].body()
  for k,v in pairs(body) do 
  print(v)
   add(t, v) end 
 end
 return grid(1, 1, 120, 100, t)
end

function set_blank() return 0 end

function set_wall() return 1 end

function either(a, b)
 if (nil == a) return b
 return a
end