Terms are constants, variables or integers. Terms are to be entered into Predicates. Predicate is also called a Structure. Functional programming languages don t use class hierarchy. In Functional programming languages, where list structure s are the primary data structure available, they use recursion to control mechanism for repeating sequences of statements.
Functional programming describes all computer operations as mathematical functions on inputs.
Typically, a function can be created and returned from other functions as first-class data. This function object may then be passed as input to other functions, perhaps be composed with other functions, and eventually, and applied to input to produce a value. Objects can be defined in terms of functions that encapsulate certain data, and operations on objects can be defined by functions encapsulating the objects. Purely functional languages do not have assignment, as all side effecting can be defined in terms of functions that encapsulate the changed data. In logic languages a different approach is used.