Added extra files to Haskell directory

[MitchStevens]

Added solutions to the transformerBST problem (which has a really nice solution in haskell) and the dice problem. Will add documentation and tests soon. Might also be a good idea to run cabal init and make this collection of files a single project, like in the Scala and Closure sections.

[ashwinbhaskar]

@MitchStevens Hey, that's really nice! I would suggest a small change, though.

1. Can you prepend your commit messages with [Haskell-Way] for consistency?
2. Please remove the License file. We will add a single license file for the whole repo in the root.
3. Remove the readme in haskell and append it to the README of the repo. The read me can be added to the readme of the repo.

You can amend the commits and do a force push

[jvanbruegge]

The code can be simplified a lot. In the end you just have:

{-# LANGUAGE DeriveFunctor #-}
{-# LANGUAGE DeriveFoldable #-}
{-# LANGUAGE DeriveTraversable #-}

module TransformBST where

import Data.Traversable (mapAccumR)

data Tree a = Branch (Tree a) a (Tree a) | Bud
    deriving (Show, Functor, Foldable, Traversable)

transformBST :: Num a => Tree a -> Tree a
transformBST = snd . mapAccumR (\a b -> (a + b, a)) 0

[jvanbruegge]

This can be derived by DeriveFunctor

[jvanbruegge]

This can be derived by DeriveFoldable

[jvanbruegge]

This can be derived by DeriveTraversable