Grammar rules in Prolog are both a convenient way to express definite clause grammars and an extension of the well known context-free grammars. More...

Detailed Description

Grammar rules in Prolog are both a convenient way to express definite clause grammars and an extension of the well known context-free grammars.

A grammar rule is of the form:

-->

where both head and body are sequences of one or more items linked by the standard conjunction operator ,

Items can be:

a non-terminal symbol may be either a complex term or an atom
a terminal symbol may be any Prolog symbol Terminals are written as Prolog lists
an empty body is written as the empty list [ ]
extra conditions may be inserted as Prolog procedure calls, by being written inside curly brackets { and }
the left side of a rule consists of a nonterminal and an optional list of terminals
alternatives may be stated in the right-hand side of the rule by using the disjunction operator ;
the cut and conditional symbol (->) may be inserted in the right hand side of a grammar rule

Grammar related built-in predicates:

Class Documentation

◆ phrase/2

class phrase/2

phrase(+ P, L)

This predicate succeeds when L is a phrase of type P The same as phrase(P,L,[])

Both this predicate and the previous are used as a convenient way to start execution of grammar rules

◆ phrase/3

class phrase/3

phrase(+ P, L, R)

This predicate succeeds when the difference list _L_- _R_ is a phrase of type P