Thursday, May 5, 2016

April 2016 1HaskellADay 1Liners

  • April 15th, 2016:
    (\(intensf, list) -> map (second intensf) list) (insensifierFn, assocList)
    Point-free-itize this lambda
    • obadz @obadzz uncurry $ map . second
  • April 15th, 2016:
    foldr (\card -> let c = color card in mappend c *** ((idx card, c):))
           (mempty, []) cards
    Point-free-itize and de-let lambda
    • Gautier DI FOLCO @gautier_difolco foldr (uncurry (***) . (uncurry fmap . fmap (((,) =<< mappend) . color) . ((,) =<< ((:) .) . (,) . idx))) (mempty, []) cards
    • me: foldr (uncurry (***) . (mappend . snd &&& (:)) . (idx &&& color)) (mempty, [])
  • April 15th, 2016: map (\(idx, color) -> C idx (cell bb idx) color) assoclist
    point-free-itize the lambda in the map function.
    • Eyal Lotem @EyalL uncurry (C <*> cell bb) ?
      Not in front of a type checker, can't check myself :)
  • April 13th, 2016:
    point-free-itize lambda term in:
    uncurry (foldr (\a -> min a *** max a)) . ((head &&& head) &&& id)
    • obadz @obadzz liftA2 (***) min max
  • April 12th, 2016:
    minmax :: Ord a => [a] -> (a, a)
    minmax [1..9] = (1,9)
    in linear time.
    minmax = minimum &&& maximum
    fails as it's 2x too slow.
  • April 12th, 2016:
    You have (a,b) (c,d)
    You need (a*c, b*d)

    Well, we don't have all day! (Actually, we do) Get to it!
    Pointless; I MEAN POINT-FREE pls
    • lotz@Haskell㌠ @lotz84_ ((uncurry . flip . curry $ id).) . ((uncurry.) . uncurry . (flip.) . flip . flip) ((((flip . (flip.)) $ ((,).) . (*)).) . (*))
    • Olivier Iffrig @oiffrig Point-free but star-full: uncurry (***) . ((*) *** (*))
    • bazzargh @bazzargh curry((uncurry (*)) *** (uncurry (*)))
    • bazzargh @bazzargh knew there had to be a bimap answer, eventually got: curry ((bimap <$> id <*> id) (uncurry (*)))
    • obadz @obadzz join biliftA2 (*)
    • Андреев Кирилл @nonaem00 (((product *** product) . unzip) .) . (flip (:)) . (:[]) ... I clearly need more coffee this morning.
  • April 10th, 2016:

    data BBx = Bx (Int, Int) Pt2D Pt2D

    define:
    mkBB :: [a] -> Pt2D -> BBx
    mkBB xs extents = Bx (0, length xs) (0,0) extents
    points-free
    • Gautier DI FOLCO @gautier_difolco
      -- LANGUAGE TupleSections
      data BBx = Bx (Int, Int) Pt2D Pt2D
      mkBB :: [a] -> Pt2D -> BBx
      mkBB = flip Bx (0,0) . (0, ) . length
    • Thomas D @tthomasdd mkBB = flip Bx (0,0) . (,) 0 . length
  • April 7th, 2016:
    type MList a n = [(a, n)]
    partSz :: Ord n => n -> MList a n -> (MList a n, MList a n)
    partSz µ = partition ((µ >) . snd)
    Define points-free
    • partSz = partition . (. snd) . (>)  -- via @gautier_difolco
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Monday, May 2, 2016

April 2016 1HaskellADay Problem and Solutions

April 2016

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