Another language widely known for the many languages that use it as a basis, Haskell is another general-purpose, multi-paradigm, purely functional language. The “purely functional” part means that Haskell’s functions only depend on their arguments, regardless of their global or local states. That makes it easier to understand, which is why Haskel is mostly used for academic reasons (though there it also has industry-wide uses as well). 

Haskell () is a general-purpose, statically typed, purely functional programming language with type inference and lazy evaluation. Designed for teaching, research and industrial application, Haskell has pioneered a number of advanced programming language features such as type classes, which enable type-safe operator overloading.