High Quality Content by WIKIPEDIA articles! In programming language theory, an anonymous function (also function constant or function literal) is a function (or a subroutine) defined, and possibly called, without being bound to an identifier. Anonymous functions are convenient to pass as an argument to a higher-order function and are ubiquitous in languages with first-class functions such as Haskell. Anonymous functions are a form of nested function, in that they allow access to the variable in the scope of the containing function (non-local variables). Unlike named nested functions, they cannot be recursive without the assistance of a fixpoint operator (also known as an anonymous fixpoint or anonymous recursion).