3 ms·

> with records of closures. Interesting. Can you point me to an example?

• Jtsummers 12y ago
  http://c2.com/cgi/wiki?ClosuresAndObjectsAreEquivalent http://c2.com/cgi/wiki?ClosuresAndObjectsAreEquivalent http://okmij.org/ftp/Scheme/oop-in-fp.txt http://okmij.org/ftp/Scheme/oop-in-fp.txt http://stackoverflow.com/questions/2954642/methods-and-properties-in-scheme-is-oop-possible-in-scheme http://stackoverflow.com/questions/2954642/methods-and-prope... http://mitpress.mit.edu/sicp/full-text/book/book-Z-H-20.html http://mitpress.mit.edu/sicp/full-text/book/book-Z-H-20.html Some examples. The first is a discussion on it. The second and third have examples in scheme. I'd type more but I'm on my iPad. If I get time later I'll steal time on someone's computer to type up more.
• dllthomas 12y ago
  Jtsummers gave some links, but in the interest of having something here: data Surface = Surface -- presumably provided by drawing backend data Shape = Shape { shapeGetCenter :: (Int, Int) , shapeSetCenter :: Int -> Int -> Shape , shapeDraw :: Surface -> IO () , shapeScale :: Double -> Shape , shapeGetAABB :: (Int, Int, Int, Int) , shapeShow :: String } instance Show Shape where show = shapeShow circle r x y = Shape { shapeGetCenter = (x, y) , shapeSetCenter = circle r , shapeDraw = undefined -- draw shape to surface , shapeScale = \ f -> circle (f * r) x y , shapeGetAABB = ( floor $ fromIntegral x - r/2 , floor $ fromIntegral y - r/2 , ceiling $ fromIntegral x + r/2 , ceiling $ fromIntegral y + r/2 ) , shapeShow = unwords [ "circle", show r, show x, show y ] } box w h theta x y = Shape { shapeGetCenter = (x, y) , shapeSetCenter = box w h theta , shapeDraw = undefined -- draw shape to surface , shapeScale = \ f -> box (w * f) (h * f) theta x y , shapeGetAABB = let w' = h * abs (sin theta) + w * abs (cos theta) h' = w * abs (sin theta) + h * abs (cos theta) in ( floor $ fromIntegral x - w'/2 , floor $ fromIntegral y - h'/2 , ceiling $ fromIntegral x + w'/2 , ceiling $ fromIntegral y + h'/2 ) , shapeShow = unwords [ "box", show w, show theta, show x, show y ] }