Reading a Grid

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.