Hello,

(I downloaded gsd/gsll a few days ago)

In the documentation section 3.2.1 map-grid, the following example does not work:

(map-grid :source 'index-fill-decadal :source-dims '(3 4))

Instead, it should probably include the `destination-specification':

(map-grid :source #'index-fill-decadal :source-dims '(3 4) :destination-specification '((array 3 4) double-float)).

The map-grid documentation is a bit unclear. It says that if `destination-specification' is not provided, map-grid defaults to `source'. But source is a function.

Looking at map-n-grids code in map.lisp, I don't see a test clause that handles the case of unspecified `destination-specification'

Mirko