🚀 go-pugleaf

Ever have one of those times when you just can't seem to do anything
right?  Well, not only have I been posting code in a language hardly
anybody ever uses (and which does not yet have efficient
implementations), I've been posting code which is conceptually flawed.

Just for the record, and for the one or two people who might be
programming in J, here's a workable implementation of the xor cursor
concept:

  screen =. get_screen ''
  put_screen    screen ~: (-$screen) {. (position + $cursor) {. cursor

And, if anyone is actually reading this post I suppose I ought to
grant you the courtesy of explaining what this code is about...

The following are bit_maps: the variable 'cursor' the result of
'get_screen' (and thus, the variable 'screen') and the argument to
'put_screen'.  'position' is an x y coordinate pair.  '{.' extends a
bitmap to some specific size (to the upper left, with positive left
arguments, and to the lower right with negative left arguments).
$screen gives the size of the screen bitmap (the same type of value as
'position'), and $cursor gives the size of the cursor bitmap.

And, yeah, '~:' still toggles bits, and all of this is matrix notation
stuff...

--------

I wonder... anybody for a contest to simulate violating as many
patents as possible with minimal code (e.g. one line per patent, or
whatever)?

-- 
Raul <rockwell@socrates.umd.edu>