Building Parsers with Java™

13.9. Lists

The basic collection class in Logikus is the list. You can write a list as a pair of brackets containing a series of terms. For example, here is a list of synonyms for French roasted coffee:

[dark, full, high, viennese, continental] 

There are many ways to write a list that unifies with this one. First, any list that contains the same number of elements will unify with this list if each term unifies with its corresponding element. For example, each of the following lists unifies with the list of synonyms:

[A, B, C, D, E] 

[dark, full, A, B, continental]

You can also describe a list in terms of its head elements and its tail, indicating the tail after a vertical bar. The tail of a list is always itself a list. For example, the following ...