compound context sp fn: display-grid

display-grid:
    description:
        display-grid[width, height]
        display-grid[width, height, operator]
        display-grid[width, height, operator, empty-char]
        display-grid[width, height, operator, empty-char, cell-prefix]
        display a rectangular map of the given width and height
        where each cell is the value of "operator" applied to that cell (default operator is "value")
        where empty-char is printed for cells with value 0 (default value of empty-char is ".")
        where cell-prefix is the prefix string for the cells (default value is "grid: ")

    examples:
        -- learn a small grid first:
        learn-grid[9,5]

        -- learn some cell values:
        value |grid: 2: 2> => |H>
        value |grid: 2: 3> => |e>
        value |grid: 2: 4> => |l>
        value |grid: 2: 5> => |l>
        value |grid: 2: 6> => |o>

        -- display the resulting grid:
        display-grid[9, 5, value, "*"]
            width:  9
            height: 5

            0      *   *   *   *   *   *   *   *   *
            1      *   *   *   *   *   *   *   *   *
            2      *   *   H   e   l   l   o   *   *
            3      *   *   *   *   *   *   *   *   *
            4      *   *   *   *   *   *   *   *   *

    see also:
        learn-grid, grid-simm, similar-grid