plaidfinch

pascal :: Z2 Int Int Integer
pascal = evaluate $ sheet (0,0) 0 $
  repeat 1 : repeat (1 : pascalRow)
  where pascalRow = repeat $ cell above + cell left
  
pascalLists :: [[Integer]]
pascalLists = map pascalList [0..]
   where
      pascalList n =
         map view .

plaidfinch

evaluate :: ComonadApply f => f (f b -> b) -> f b
evaluate fs = fix $ (fs <@>) . duplicate