Word capitalization with Haskell

We have this problem, given a string of words, capitalize just the first letter, but the main trouble here is the lack of a common pattern to distinguish between one and another, for example:

"helloanyonethere" -> "HelloAnyoneThere"
"himartin" -> "HiMartin"
"hellorange" -> "HelloRange"
"thereach" -> "TheReach"

Well, the trouble can be addressed using Haskell, list and the always opportune recursion. The input information would be a dictionary that contains all possible words and the string to analyze; the output should be an string with the capitalized letters.

Pentagonal Numbers in Haskell

As part of my refresh on algorithms, data structures and programming, I found this interesting mathematic problem:

Pentagonal numbers are generated by the formula, P_n=n(3n1)/2. The first ten pentagonal numbers are:

1, 5, 12, 22, 35, 51, 70, 92, 117, 145, ...

It can be seen that P₄ + P₇ = 22 + 70 = 92 = P₈. However, their difference, 70  22 = 48, is not pentagonal.

Find the pair of pentagonal numbers, P_j and P_k, for which their sum and difference are pentagonal and D = |P_k  P_j| is minimised; what is the value of D?

Then, I decided to elaborate a program in Haskell that would find the number D. Of course, you can find the code in Github.