Structures

A structure takes the form of $f(t_1,\ldots,t_n)$, unless $f$ is declared to be an operator, where f is an n-ary function symbol (functor) and $t_1, \ldots, t_n$ are terms. The terms enclosed in the parentheses are called components of the structure.

Lists are special structures whose functors are '.'. The special atom '[]' denotes an empty list. The list [H|T] denotes the structure '.'(H,T).