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?