What is monad in functional programming?
Can you show me example of implementation of monad in Haskell?
A monad is a type with a function that creates that type, and a function that produces a new computation for values of that type.
Here is an example implementation of a monad `m` in Haskell:
```haskell
-- type constructor for the monad
data m a = ...
-- embed the input value in the monad `m`
return :: a -> m a
-- bind function that returns a computation to combine `a` and `m b` into `m b`
(>>=) :: m a -> (a -> m b) -> m b
```
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