Full Syntax Reference

This document provides a complete, quick-reference guide to all syntax and features in the MON language. It serves as your go-to resource for understanding the data serialization syntax and configuration language syntax of MON.

1. File Structure

A valid MON file can optionally start with one or more import statements, followed by a single root object.

// Optional imports first
import * as my_module from "./my_module.mon"

// Then, the single root object
{
    // All content, including declarations and values, goes inside this object.
}

2. Primitives

Type	Examples
String	"hello", "with spaces"
Number	123, -45.6
Boolean	true, false, on, off
Null	null

3. Comments

Single-line comments start with //.

{
    // This is a comment.
    key: "value", // This is also a comment.
}

4. Objects and Keys

• Objects are collections of key: value pairs inside {}.
• Keys can be unquoted identifiers or quoted strings.
• A trailing comma is allowed after the last member.

{
    unquoted_key: "value",
    "quoted-key-with-hyphens": 123,
}

5. Arrays

• Arrays are ordered lists of values inside [].
• A trailing comma is allowed after the last element.

{
    my_array: ["a", 1, true, null],
}

6. Composition

Feature	Syntax	Description
Anchor	&my_anchor: value,	Gives a value a file-local nickname. Must be a key-value pair.
Alias	*my_anchor	Creates a deep copy of the anchored value.
Object Spread	{ ...*my_anchor }	Merges keys from an anchored object. Local keys override spread keys.
Array Spread	[ ...*my_anchor ]	Inserts elements from an anchored array into a new array.

7. Type System

Feature	Syntax	Description
Enum Definition	MyEnum: #enum { A, B },	Defines a type with a fixed set of choices.
Enum Access	$MyEnum.A	References a specific variant of an enum.
Struct Definition	MyStruct: #struct { f(T), g(N)=d },	Defines a schema for an object. f is a required field of type T. g is an optional field of type N with a default value d.
Struct Validation	my_instance :: MyStruct = { ... }	Validates that the object literal on the right conforms to the MyStruct schema.

8. Collection Types

Used within #struct field definitions (e.g., my_field([String...])).

Pattern	Meaning
[T]	An array with exactly one element of type T.
[T...]	An array with zero or more elements, all of type T.
[T1, T2]	A tuple with exactly two elements of specified types.
[T1, T2...]	An array with one or more elements, where the first is T1 and the rest are T2.
[T1..., T2]	An array with one or more elements, where the last is T2 and the rest are T1.
Any	A special type that matches any value.

9. Module System

Import statements must be declared at the top of a file, before the root object.

• Implicit Exports: All top-level keys in a file are importable.
• Namespace Import: import * as ns from "./file.mon"
• Named Import: import { Member1, &Anchor2 } from "./file.mon"

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