compact-coretypescript-integration

name	compact-core:typescript-integration
description	Use when implementing witness functions in TypeScript, mapping Compact types to TypeScript (Field→bigint, Bytes→Uint8Array), deploying contracts, calling circuits from TypeScript, reading ledger state, or building Midnight DApps with the JavaScript SDK.

TypeScript Integration

Complete guide to integrating Midnight Compact contracts with TypeScript applications.

Type Mapping Quick Reference

Compact Type	TypeScript Type	Notes
Field	bigint	ZK field element
Uint<N>	bigint	Any bit width maps to bigint
Boolean	boolean	Direct mapping
Bytes<N>	Uint8Array	Fixed-length byte array
Opaque<'string'>	string	UTF-8 string data
Opaque<'Uint8Array'>	Uint8Array	Binary data
struct	{ field: Type, ... }	Object with typed fields
enum	Discriminated union	{ tag: 'Variant', value: T }
Vector<T, N>	T[]	Array of mapped type

Witness Implementation Pattern

import { WitnessContext } from '@midnight-ntwrk/midnight-js-types';

// Compact declaration: witness get_secret(): Field;
const witnesses = {
  get_secret: ({ privateState }: WitnessContext<PrivateState>): bigint => {
    return privateState.secret;
  }
};

Contract Interaction Flow

1. Compile Compact → Generated TypeScript types
2. Deploy contract → Get contract address
3. Create provider → Connect to Midnight node
4. Build witnesses → Implement private data access
5. Call circuits → Execute transactions
6. Read state → Query ledger values

Quick Examples

Calling a Circuit

import { Contract } from './contract';

const result = await contract.callTx.transfer({
  to: recipientAddress,
  amount: 1000n
}, witnesses);

Reading Ledger State

const balance = await contract.state.balances.get(userAddress);
// balance: bigint | undefined

Deploying a Contract

import { deployContract } from '@midnight-ntwrk/midnight-js-contracts';

const { contract, address } = await deployContract(provider, {
  privateStateKey: 'my-contract',
  initialPrivateState: { secret: 42n },
  witnesses
});

References

For detailed documentation on each topic:

• Type Mapping - Complete Compact ↔ TypeScript type correspondence
• Witness Bridge - Implementing witnesses in TypeScript
• Contract API - Generated contract interface usage
• Deployment - Contract deployment from TypeScript

Examples

Working TypeScript examples:

• Witness Implementation - Complete witness patterns
• Deploy Contract - Contract deployment flow
• Read State - Reading ledger state