[Haskell-beginners] Implement semantic editor combinators

Hi, I read Conal Elliott's "Semantic editor combinators" and write myself a tutorial to answer how it works and give some observations about it, here I want to share it with you: http://javran.github.io/posts/2014-03-21-implement-semantic-editor-combinato... Hope you enjoy it and please feel free to give me comments and indicate my misconceptions. Thanks, Javran