a parameterized module , or a generic structure , that is defined in terms of zero or more argument structures with a specified signature
Characterized by its name, which is an atom, and the arity or number of arguements.
Combination of name and arity of a compound term. The term foo(a, b, c) is said to be a term belonging to the functor foo/3. foo/0 is used to refer to the atom foo.
A functor is characterised by its name which is an atom, and its arity which is its number of arguments.
The functor of a compound term is its name and arity. For example, the compound term foo(a,b) is said to have “the functor foo of arity twoâ€, which is generally written foo/2. The functor of a constant is the term itself paired with zero. For example, the constant nl is said to have “the functor nl of arity zeroâ€, which is generally written nl/0.