What is functional database language?

A functional database language is a type of programming language that combines the principles of functional programming with database querying and manipulation. It allows for the expression of database operations using functions, enabling developers to perform complex queries and data transformations in a more declarative and concise manner. Examples include languages like SQL with functional extensions, or entirely functional languages designed for working with data, such as Haskell with database libraries. This approach often emphasizes immutability and higher-order functions, promoting cleaner and more maintainable code.