A value of type CellGrid a is a rectangular array of values of type a.

A cell can be in the interior of the grid, on an edge, on in a cornder

CellRenderer is a record that provides the information -- cellSize, defaultColor, and the function cellColorizer -- that are needed to render a cell to SVG.

Render a cell grid as Html

Transform a CellGrid a with a function ((Int, Int) -> a -> a)

return the type of the cell at location (i,j). Thus classifyCell grid (0,0) = Corner

Return the Maybe value of the cell at (i,j) from grid

Set the value of the cell at location (i,j)

Consider a 1D array of elements which represents a 2D array with n rows. Then location n (i,j) is the index in the 1D array of the correspondng element in the 2D array at location (i,j)`

Conversely, index (nRows, nCols) k is the 2D array index (i,j) of the element al address k

Return a list of all indices (i,j) of a grid. Useful for mapping.