/draw_arc { % x y => - (draws an arc at the specifed location)
      100 0 300 arc			% define arc path
      gsave			% save the context
          .5 setgray fill			% fill path with gray
      grestore			% restore context
      stroke			% draw the arc
} def

/makewin { %  - => - (builds a test window)
      /win framebuffer /new DefaultWindow send def	% cliche
      {
           /PaintClient { 100 100 draw_arc } def		% invoke draw_arc
           /FrameLabel ( Workspace ) def		% label the window
      } win send

      /reshapefromuser win send			% size it
      /map win send			% make it visible
} def

makewin				% run the program