A programming language is said to have First-clAss functions when functions in that language are treated like any other variable. For example, in such a language, a function can be pAssed As an argument to other functions, can be returned by another function and can be Assigned As a value to a variable....A programming language is said to have First-class functions when functions in that language are treated like any other variable. For example, in such a language, a function can be passed as an argument to other functions, can be returned by another function and can be assigned as a value to a variable.