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|Representing text: strings, atoms and code lists|
With the introduction of strings as a Prolog data type, there are three main ways to represent text: using strings, atoms or code lists. This section explains what to choose for what purpose. Both strings and atoms are atomic objects: you can only look inside them using dedicated predicates. Lists of character codes are compound datastructures.
'Boeing 747'), but also individual words in a natural language processing system. They are also used where other languages would use enumerated types, such as the names of days in the week. Unlike enumerated types, Prolog atoms do not form not a fixed set and the same atom can represent different things in different contexts.