haskal nomad?

Modelling monads with a typeclass is stupid. There isn't one true monad for a given type. It makes no sense that when you use bind with lists you automatically get concatmap.

So. We introduce the notion of category. This kind of very abstract entity (even more abstract than a set). In a sense, the category consists of two things: a set of objects and a set of morphisms. With respect to these objects and morphisms given some axioms there. They imply that the category can be represented as a directed graph, where vertices - is an object category, and the arch - a morphisms. It is essential that a morphism as in the arc of the graph, there is a "beginning" and "end" (called the domain name and code), and are objects of the same category. Domain and the code of the morphism (beginning and end of the arc of the graph) can match. Such a morphism is called an endomorphism.

A more interesting example for us: the category Hask. Here objects - are data types that are possible in language Haskell, and morphisms - features of Haskell.