flex Expert System Toolkit - LPIS

7. Knowledge Specification Language 61
7. The KSL
KSL Terms
Comments
Punctuation
Numbers
Atoms
flex toolkit
This chapter describes all the elements of the KSL. See also the chapter on
flex Predicates for the equivalent Prolog predicates, and the chapter on the
Run-Time Interpretation of KSL for a description of how the KSL is
compiled into Prolog.
This section describes the valid tokens and terms of the KSL. Essentially
they follow the tokenisation of Prolog's Edinburgh syntax, with a few
enhancements.
There are five types of Edinburgh token: punctuation, number, atom,
string and variable. Built on top of Edinburgh tokens are the concepts of a
KSL name and a KSL value.
Any text between the symbols /* and */ is treated as a comment and is
ignored by the flex compiler.
The % symbol indicates the start of a comment up to the end of the line on
which it occurs.
A punctuation mark is always considered as a separate token (unless it lies
within quotes), and is one of the following:
( ) [ ] { } | ! ; ,
Numbers are either integers or floating-point numbers.
Examples
211327 -32768 0 2.34 10.3e99 -
0.81
Atoms are of three types: alphanumeric, symbolic and quoted.
An alphanumeric atom is a lowercase letter (a-z) followed by a sequence of
zero or more alphabetic characters (a-z, A-Z or _) or digits (0-9).