Map loader

local terrains = {
    G = "grass",
    D = "dirt",
    R = "rock",
}

return function (mapfile)
    local new = {}
    for line in io.lines(mapfile) do
        local h = 1
        local row = {}
        for point in line:gmatch('.') do
            row[h] = terrains[point]
        end
        table.insert(new, row)
    end
    return new
end