Hello,

I'm trying to practice my Haskell. So I had the idea of making a program which, given a mother's and a child blood type, it can determine whether a certain father is possible or not.

Please take a look on this gist with my implementation:

    https://gist.github.com/aflag/14429dfb2e89791a44e2#file-parentaltesting

Would you care to comment on it? It looks a bit cumbersome to my eyes. I'm trying to find the most intuitive and elegant way of do it. I'm not so much worried with performance.

[]'s
Rafael