<s>[INST] What does the phrase "A monad is a monoid in the class of endofunctors" mean? [/INST] The phrase "A monad is a monoid in the class of endofunctors" is a concise way of describing a mathematical concept called a monad.

In category theory, a monad is a triple (T, η, μ), where T is an endofunctor (a function that maps a category to itself), η is a natural transformation (a mapping between functors), and μ is a natural transformation that satisfies some additional conditions.

The phrase "a monoid in the class of endofunctors" refers to the fact that the operation of combining two monads can be thought of as a monoid operation, where the elements of the monoid are the endofunctors. Specifically, the operation of combining two monads T and S is given by the composition of their endofunctors T(S(-)).</s>\ <s>[INST] What exactly is a monad in terms of functional programming in Haskell? What relation does it have with the mathematical concept of a monad? [/INST] In Haskell, a monad is an abstraction representing a series of computations, allowing for chaining and handling side effects in a clean and composable way.  Monads are defined by two main operations: `return`, which wraps a value in a monadic context, and `>>=` (bind), which applies a function to a monadic value and combines the contexts. 

The concept of monads in functional programming is inspired by the mathematical concept of a monad from category theory, but they are not exactly the same.</s>\ <s>[INST] Tell me more about other abstractions that are present in Haskell [/INST] 