[tromp]

Minor nitpick: the first real line of code

  alphabet = "abcdefghijklmnopqrstuvwxyz"

is better written as

  alphabet = ['a'..'z']

This is really syntactic sugar for

  enumFromTo 'a' 'z'

using the function

  enumFromTo :: Enum a => a -> a -> [a]

from the typeclass Enum for enumerable types, and the fact that a string (type String) is just a list of characters (type [Char]).

[evincarofautumn]

As long as we’re picking nits…

> I wrote this code putting brevity over readability

Overall, this is not particularly terse, for Haskell code. With all the lambdas, it looks like OCaml! For example, these are equivalent, and I find the latter clearer:

    (sortBy (\(_,c1)(_,c2) -> c2 `compare` c1))

    sortBy (flip (comparing snd))

Now, it’s not necessarily a bad thing to be explicit, but in cases such as these, it’s less repetitious to just use the standard library functions.

[quchen]

For reverse sorting, there's a type that does specifically that.

    sortBy (comparing (Down . snd))

See http://hackage.haskell.org/package/base-4.7.0.1/docs/Data-Or...

[evincarofautumn]

True, but I prefer not to use typeclasses in that way.