1. Language Fundamentals & Syntax

1.1 Lexical Structure & Conventions

Rave is a case-insensitive, textual, declarative programming language. Statements and definitions are delimited by semicolons ;. Comments follow standard C-style syntax:

/* This is a multi-line 
   comment in Rave */

// This is a single-line comment

Identifier naming conventions strictly distinguish variable references from keywords and properties:

Variables are delimited by percent signs: %variable_name%.
Keywords (external runtime inputs provided by the solver) are prefixed by context or qualified scopes: leg.%start_utc%, keywords.%departure%.
Rules begin with the keyword rule and terminate with end.

1.2 Domain Data Types

Rave blends standard general-purpose data types with domain-specific temporal and geographical types tailored for airline operations:

Type Category	Type Keyword	Description & Representation	Example Usage
General	`int` / `integer`	32-bit or 64-bit signed integer values	`3`, `142`
General	`real` / `float`	Floating-point numbers for costs/weights	`1.5`, `350.75`
General	`bool` / `boolean`	Boolean truth values	`True`, `False`
General	`string`	Textual string literals	`"SAW"`, `"Captain"`
Domain Specific	`time`	Clock time or absolute temporal stamp	`10:30`, `24:00`
Domain Specific	`duration`	Elapsed time duration (HH:MM or minutes)	`00:30`, `05:15`
Domain Specific	`datetime`	Combined calendar date and absolute time	`2026-08-11 14:00`
Domain Specific	`airport`	3-letter IATA or 4-letter ICAO airport code	`"LHR"`, `"JFK"`, `"SAW"`

1.3 Constants & Parameters

Constants and parameters establish fixed thresholds or configurable business rules.

Global Constants Block

CONSTANTS:
  %min_sit_time% = 00:30;
  %max_duty_flights% = 4;
  %base_airport% = "SAW";
ENDCONSTANTS

Bounded Parameters

Parameters allow optimization analysts to perform "what-if" scenario testing without recompiling the core rule codebase:

%max_duty_time% = parameter 08:00 minvalue 04:00 maxvalue 14:00;

1.4 Variables & Identifiers

Variables encapsulate intermediate computations. Because Rave is declarative, variables do not represent mutable memory cells; they define functional expressions bound to a specific context.

%leg_duration% = leg.%arrival_time% - leg.%departure_time%;
%duty_flight_time% = sum(leg(duty), %leg_duration%);