concept monadic type in category functional programming

This is an excerpt from Manning's book Functional Programming in JavaScript. Login to get full access to this book.

Monadic type— A particular concrete implementation of this interface

Monadic types share a lot of the same principles as the Wrapper object you learned about at the beginning of the chapter. But every monad is different and, depending on its purpose, can define different semantics driving its behavior (that is, for how map or fmap should work). These types define what it means to chain operations or nest functions of that type together, yet all must abide by the following interface:

Type constructor— Creates monadic types (similar to the Wrapper constructor).