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Lambit Documentation

Lambit is a functional TypeScript to Bitcoin Script compiler. Contracts are authored as pure TypeScript expression trees, then compiled into artifact-style JSON with ABI and locking script output.

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What Lambit provides​

AreaSummary
DSLUnified named contract() overloads plus explicit method(schema, fn) declarations.
ExpressionsTyped combinators for logic, arithmetic, bytes, crypto, and build-time array transforms.
CompilerStack compilation, state lowering, and artifact assembly into JSON v10-compatible output.
TestsGolden fixtures, compiler tests, and docs example validation.

Quick example​

The standard P2PKH helper provides the byte-minimal address check plus signature check. Use pubKey2Addr(pubkey) when authoring custom P2PKH-style predicates; it documents address intent while lowering to the same OP_HASH160 script surface as hash160(pubkey).

import {
  P2PKH,
} from '@opcat-labs/lambit';

const p2pkh = P2PKH({ addr: '00112233445566778899aabbccddeeff00112233' });
console.log(P2PKH.name); // P2PKH
console.log(p2pkh.artifact.hex); // 76a9<addr>88ac

Wrap the same predicate in assert(...) when you want assertion metadata at an explicit verify boundary.

import {
  contract,
  method,
  TypeTag,
  and,
  assert,
  eq,
  pubKey2Addr,
  checkSig,
} from '@opcat-labs/lambit';

const AssertP2PKH = contract(
  'AssertP2PKH',
  { addr: TypeTag.Ripemd160 },
  ({ props }) => ({
    unlock: method(
      { sig: TypeTag.Sig, pubkey: TypeTag.PubKey },
      (sig, pubkey) => assert(and(eq(pubKey2Addr(pubkey), props.addr), checkSig(sig, pubkey))),
    ),
  }),
);

const assertP2pkh = AssertP2PKH({ addr: '00112233445566778899aabbccddeeff00112233' });
console.log(assertP2pkh.artifact.hex); // 76a9<addr>88ac6951
note

The repository validates published TypeScript examples through docs tests so the public guide snippets stay aligned with the current API.

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