おまけ(´ー｀)

• (take,drop)の形から([a],[a])の形を返すように微調整したバージョン

splitAt5' = 
 curry((\[x,y]->(x,y)).(uncurry (flip((flip((flip(map) . flip(map)
   (map($ take,drop)) [fst,snd]) . flip($)))).flip($)))))

• 実行結果

*Main> :! type mysplit.hs
splitAt' n = flip(map)  (flip(map) [take,drop] ($ n)) . flip($)

splitAt2' n =  (flip(map) . flip(map) [take,drop] . flip($)) n.flip($)

splitAt3' = flip((flip((flip(map) . flip(map) [take,drop] . flip($)))).flip($) )

splitAt4' = flip((flip((flip(map) . flip(map) (map ($ (take,drop)) [fst,snd]) .
flip($)))).flip($) )

splitAt5' = curry((\[x,y]->(x,y)).(uncurry (flip((flip((flip(map) . flip(map) (m
ap ($ (take,drop)) [fst,snd]) . flip($)))).flip($) ))))
*Main> :l mysplit.hs
Compiling Main             ( mysplit.hs, interpreted )
Ok, modules loaded: Main.
*Main> splitAt5' 10 ['a'..'z']
("abcdefghij","klmnopqrstuvwxyz")

curryやuncurryを使ってるのは

２引数を１引数に変換

　(f x y ::Int->[a]->[[a],[a]])→(g (x,y) :: (Int,[a])->[[a],[a]] )　

関数合成をする

　(\[x,y]->(x,y)) . g(x,y) :: (Int,[a])->([a],[a]) )

１引数を２引数に戻す

　(g'(x,y)::(Int,[a])->([a],[a]) → f' x y ::Int->[a]->([a],[a]) )

つまり関数合成のための引数合わせ。