aaronbassett/compact-core:language-reference

Compact Language Reference

Complete reference for the Compact smart contract language used on Midnight Network.

Quick Reference

Primitive Types

| Type | Description | Example | |------|-------------|---------| | Field | ZK-native field element (~254 bits) | const f: Field = 42; | | Boolean | True/false value | const b: Boolean = true; | | Uint<N> | Unsigned integer (N bits, N ≤ 248) | const n: Uint<64> = 100; |

Composite Types

| Type | Description | Example | |------|-------------|---------| | Bytes<N> | Fixed-size byte array | const h: Bytes<32> = ...; | | struct | Named record type | struct Point { x: Field, y: Field } | | enum | Tagged union | enum Maybe<T> { Some(T), None } | | Vector<T, N> | Fixed-size array | const v: Vector<Field, 3> = [1, 2, 3]; |

Special Types

| Type | Description | Example | |------|-------------|---------| | Opaque<'string'> | UTF-8 string from TypeScript | witness get_name(): Opaque<'string'>; | | Opaque<'Uint8Array'> | Binary data from TypeScript | witness get_data(): Opaque<'Uint8Array'>; |

Circuit Syntax

// Public circuit callable from TypeScript
export circuit transfer(to: Bytes<32>, amount: Uint<64>): [] {
    // Circuit body
}

// Private helper circuit
circuit helper(x: Field): Field {
    return x * x;
}

Witness Syntax

// Declaration (implemented in TypeScript)
witness get_private_key(): Bytes<32>;

// Usage in circuit
export circuit sign(message: Bytes<32>): Bytes<64> {
    const key = get_private_key();
    // Use key...
}

Control Flow

// Conditional
if (condition) {
    // then branch
} else {
    // else branch
}

// Bounded loop (bounds must be compile-time constant)
for i in 0..10 {
    // loop body
}

// Assertion
assert condition, "Error message";

Module System

// Import specific items
import { hash } from "CompactStandardLibrary";

// Include entire file
include "utils.compact";

// Export for external use
export circuit public_fn(): Field { ... }

References

For detailed documentation on each topic:

• Type System - Complete type reference with constraints
• Circuits - Circuit and witness patterns
• Control Flow - Conditionals, loops, assertions
• Modules - Import, include, export, COMPACT_PATH