Multi-dimensional Typed Arrays

Grids, boards and matrices are arrays of arrays — and the type follows the same nesting: {{number}} is an array whose elements are {number} arrays.

local grid: {{number}} = {
    {1, 2, 3},
    {4, 5, 6},
    {7, 8, 9},
}

local board: {{string}} = {
    {"white", "black"},
    {"black", "white"},
}

Nested indexing reads one level at a time: grid[2] is the second row (a {number}), and grid[2][1] is that row's first element — 4. Both indices are 1-based, so the top-left corner is grid[1][1], not grid[0][0].

Watch out when a row might not exist: grid[10] is nil, so grid[10][1] raises a runtime error — you'd be indexing into nil.

You can also build grids with loops: create an empty row, fill it with table.insert, then insert the whole row into the outer array. #grid counts the rows and #grid[1] the columns of the first row:

local table10: {{number}} = {}
for i = 1, 3 do
    local row: {number} = {}
    for j = 1, 4 do
        table.insert(row, i * j)
    end
    table.insert(table10, row)
end