August 2017 1HaskellADay 1Liners Problems and Solutions

• August 1st, 2017:
f :: (Maybe a, b) -> Maybe (a, b) Define points-free.
• August 1st, 2017:
  Given f above and f a and f b are mutually exclusive in Maybe monad, define
  g :: Maybe (a, b) -> Maybe (a, b) -> (Maybe a, b)
  points free
• August 1st, 2017:
  Now, let's define the dual of f
  f' :: Maybe (a, b) -> (Maybe a, b)
  points free

August 2017 1HaskellADay problems and solutions

• August 31st, 2017: Today's #haskell exercise is by way of @ahnqir. What are the percentage of facebook users by country? Today's #haskell solution charts FB users by country. GO INDIA! 
  
• August 4th, 2017: For today's #haskell problem we are looking at the caesar cipher as a better rot13. And today's #haskell solution with rot, rot, roslein rot everywhere.  
• August 1st, 2017: For today's #haskell problem we are parsing a string into word-tokens and munging/demunging them with rot13! WOOT! Munging plaintext and demunging cyphertext, oh, my! 

July 2017 1HaskellADay 1Liner

• July 7th, 2017:
  In LU-decomposition of matrices you have square P-matrix:
  [[1,0..],
   [0,2,0..],
   [0,0,3,0..],
  ...]
  For matrices of n² size
  Code that
  
  • ∃! David Turner @DaveCTurner
  • matrix n = let td = take n . drop 1 in td [td $ replicate i 0 ++ [i] ++ repeat 0 | i <- [0..]]

July 2017 1HaskellADay Problems and Solutions

• July 26th, 2017: We look at unifying fresh variables to ground terms for today's #haskell problem. And we have unification working for free variables and ground terms for today's #haskell solution. 
• July 25th, 2017: We look at the beginnings of unification with ground terms for today's #haskell problem. Today's #haskell solution shows unification of ground terms in a monadic domain. 
• July 24th, 2017: Commuters today occupy my mind for today's #haskell problem. A little reasoning, a little harsh reality, and we have today's #haskell solution. 
• July 20th, 2017: I didn't go for my morning jog, so today's #haskell problem looks at running ... expressions. Eheh. For today's #haskell solution, some people run on empty, but I run on LOGIC! ... same thing. 
• July 19th, 2017: Today's #haskell problem is our first step in our scheme to reasoning! MWA-HAHA! via the Reasoned Schemer. Today's #haskell solution:some days are #s; some days are #u 
  
  
  
  
• July 7th, 2017: It's FRIDAY, and you know what that means? SCRABBLE DAY! for today's #haskell problem 
• July 6th, 2017: For today's #haskell problem we invert a matrix to solve a system of equations. 
• July 5th, 2017: For today's #haskell problem we have a * b = c ... HOW HARD CAN THAT BE? #famouslastwords The #haskell solution took like a whole second! THAT WAS HARD! 
• July 4th, 2017: Boys and girls! Gather 'round as I spin you a story of Jemima and Roland for today's #haskell problem. 
• July 3rd, 2017: Today's #haskell problem is all 'bout the Ord, 'bout the Ord, 'bout the Ord. No Functor. Today's #haskell solution uses a little sorting logic (not sordid logic; that's different) to show Jim is the eldest.
  

June 2017 1HaskellADay 1Liners

• June 17th, 2017:
  f :: (a, [a]) -> [a] -> [a]
  f (c, w1) w2 = c:w1 ++ w2
  
  Define f points-free
• bazzargh @bazzargh (++).uncurry(:)
• Felt there must be a nicer way to exploit symmetry of mappend.uncurry(mappend.pure) but can't find it

June 2017 1HaskellADay Problems and Solutions

• June 21st, 2017: Today's #haskell problem connects to and queries a SQL database of your choosing. 
• June 16th, 2017: Today's #haskell problem has us interacting with the OS environment in anticipation of SQL database queries. Today's #haskell solution uses Applicative Functors to string together values we collect from the OS environment.
• June 15th, 2017: Today's Haskell problem comes by way of @aisamanra, Mr. Lists-are-Mu-functions-in-the-function-of-Mus. Today's #haskell solution shows Lists are Mu-functors! ... now, making them instances of type-classes, however ... 
  
• June 14th, 2017: Today's #haskell problem is brought by way of @matthieubulte: approximating solutions with Runge-Kutta. The #haskell solution shows I can (ψ, ε, k) with the best of them! AHA! ... but is it the CORRECT solution? 🙄 
  
• June 6th, 2017: In today's #haskell problem, we go clockwise around a binary tree, because ... we've had one too many? 

May 2017 1Liners 1HaskellADay

• May 10th, 2017:
  Define (^) :: (a -> a) -> Int -> (a -> a)
  The 'power'-function where f ^ 3 = f . f . f
• Conor McBride @pigworker flip ((ala Endo foldMap .) . replicate)