Wumpus

Copperbox revision 717.

An experiment with a new Picture type that is a function from Frame -> PostScript rather than Point -> PostScript.

I've an intuition that the Image type in Haven (Point -> Colour) is actually equivalent to an affine frame with the caveat that the basis vectors are orthonormal: affine frames are represented by the triple (o,vec-x,vec-y) - o is the origin, vec-x and vec-y are the basis vectors; if the basis vectors are orthonormal then you get a standard grid, if they aren't orthonormal you get scaling, shearing, or rotation.

I've previously decided that a generalization of Point -> Colour doesn't work too well for PostScript (as PostScript images are discrete), but I've been stumped as to what a better type might be. Introducing Frame as the function's domain does seem to be more aligned with the coordinate free approach developed by Tony DeRose and others which is one of my reference points in designing Wumpus.