offf cok bayik oluyo her seferinde

neden böyle nedennnn

Mathematically, monads are governed by set of laws that should hold for the monadic operations. This idea of laws is not unique to monads: Haskell includes other operations that are governed, at least informally, by laws. For example, x /= y and not (x == y) ought to be the same for any type of values being compared. However, there is no guarantee of this: both == and /= are separate methods in the Eq class and there is no way to assure that == and =/ are related in this manner. In the same sense, the monadic laws presented here are not enforced by Haskell, but ought be obeyed by any instances of a monadic class. The monad laws give insight into the underlying structure of monads: by examining these laws, we hope to give a feel for how monads are used.

The Functor class, already discussed in section 5, defines a single operation: fmap. The map function applies an operation to the objects inside a container (polymorphic types can be thought of as containers for values of another type), returning a container of the same shape. These laws apply to fmap in the class Functor:

fmap id = id
fmap (f . g) = fmap f . fmap g