USING: kernel accessors prettyprint namespaces math math.constants syntax ;
IN: scratchpad

TUPLE: rectangle { width float }  { height float } ;
: <rectangle> ( -- rectangle )
   rectangle new ;

TUPLE: circle { radius float } ;
: <circle> ( -- circle )
   circle new ;

GENERIC: area

M: rectangle area ( rectangle -- x )
   dup width>> swap height>> * ;

M: circle area ( circle -- x )
   radius>> dup * pi * ;

<rectangle>
   100 >>width
   50 >>height
area .

<circle>
   10 >>radius
area .