Introduction

This book is a tutorial and reference for CEL: its tokens, literals, basic types, operators, and collections.

Every CEL source form is an expression: it produces a value or helps compose one. Identifiers, calls, operators, collections, control flow, casts, and closures all participate in the same expression language.

The tutorial chapters follow this order:

1. Lexical conventions explains tokens, whitespace, comments, identifiers, and punctuation.
2. Literals and types explains scalar, compound, and closure values.
3. Operators explains precedence, associativity, arithmetic, comparison, logical, bitwise, cast, and range operators.
4. Conditional expressions explains value-producing if expressions.
5. Collections explains tuples and homogeneous arrays.
6. Closures explains closure literals and parameter typing.
7. Standard library explains additional operations available when the evaluation environment installs the library.

The Reference Manual gathers the complete grammar, exact operator rules, type names, library operations, and edge cases in one place.