This Language Reference doubles as a tutorial by embedding examples that illustrate the features being presented. Details about running the examples are given in the Getting Started section. Note that the eXPL script files are located in the main resources folder of the tutorial module and that they are organized by Tutorial number. The order of topics is not by importance, but instead is intended to avoid introducing features in advance of being covered by the Reference.

Compared to Java, eXPL is a small, terse language and is expected to be easily learnt. The most significant concept to master is that of unification, which propels execution and shapes the language design. For a Java programmer, the first big impact of unification is that it reverses the concept of data hiding and encapsulation which Java classes embody. The class is split asunder with data going into axioms and methods into templates.