ZML Language Specification

ZML (Zero-cost Module Language) is a declarative configuration language designed for REST MCP servers. It aims to replace verbose JSON configuration with concise, type-safe syntax, providing better readability and maintainability.

1. Basic Syntax

1.1 Comments

ZML supports single-line and multi-line comments, similar to C/C++/Java/Rust syntax.

// This is a single-line comment

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

1.2 Identifiers

Identifiers consist of letters, numbers, and underscores, and must start with a letter or underscore.

user_id
Product123
_internal_var

1.3 Literals

The following types of literals are supported:

• String: Enclosed in double quotes, e.g., "hello world"
• Integer: e.g., 42, -10
• Float: e.g., 3.14, -0.01
• Boolean: true, false

2. Module

Module is the top-level structure in ZML, used to organize related API definitions.

2.1 Definition

Use the module keyword to define a module.

module user {
    // Module content
}

2.2 Module Attributes

Attributes can be defined directly inside a module. Common attributes include:

• version: Module version (string)
• description: Module description (string)
• enabled: Whether enabled (boolean)
• access_level: Access level (public/private/internal)
• base_url: Base URL (string)

module user {
    version: "1.0.0"
    description: "User Management Module"
    enabled: true
}

3. Type System

ZML provides a rich type system to describe data structures.

3.1 Basic Types

Type	Description
string	String text
integer	Integer
number	Floating point number
boolean	Boolean value
date	Date (YYYY-MM-DD)
datetime	Date time (ISO 8601)
any	Any type

3.2 Composite Types

Array

Use array<Type> syntax.

array<string>
array<integer>
array<User>

Object

Use object { ... } syntax to define anonymous object structures.