Declarative workflow DSL for orchestrating complex business operations in Node.js / TypeScript.
Documentation · npm · Package README
npm install @celom/proseimport{createFlow,ValidationError}from'@celom/prose';constcheckout=createFlow<{userId: string;cart: CartItem[];coupon?: string}>('checkout').validate('inputs',(ctx)=>{if(ctx.input.cart.length===0)throwValidationError.single('cart','Cart is empty');}).parallel('hydrate','shallow',async(ctx)=>({user: awaitdb.users.find(ctx.input.userId)}),async(ctx)=>({stock: awaitinventory.check(ctx.input.cart,{signal: ctx.signal})}),).breakIf((ctx)=>ctx.state.stock.outOfStock.length>0,(ctx)=>({status: 'out_of_stock'asconst,items: ctx.state.stock.outOfStock}),).stepIf('applyCoupon',(ctx)=>!!ctx.input.coupon,async(ctx)=>{constdiscount=awaitpricing.redeem(ctx.input.coupon!,ctx.state.user.id);return{ discount };}).step('chargeCard',async(ctx)=>{constreceipt=awaitstripe.charge({userId: ctx.state.user.id,amount: total(ctx.input.cart,ctx.state.discount),signal: ctx.signal,});return{ receipt };}).withRetry({maxAttempts: 3,delayMs: 200,backoffMultiplier: 2,shouldRetry: (e)=>e.code!=='card_declined',}).transaction('persist',async(ctx,tx)=>{constorder=awaittx.orders.insert({userId: ctx.state.user.id,items: ctx.input.cart,receiptId: ctx.state.receipt.id,});awaittx.inventory.decrement(ctx.input.cart);return{ order };}).events('outbox',[(ctx)=>({eventType: 'order.placed',orderId: ctx.state.order.id}),(ctx)=>({eventType: 'payment.succeeded',receiptId: ctx.state.receipt.id}),]).map((_,state)=>({status: 'placed'asconst,orderId: state.order.id})).build();awaitcheckout.execute({userId: 'u_42', cart,coupon: 'WELCOME10'},{ db, stripe, inventory, pricing, eventPublisher },{timeout: 15_000,observer: pinoObserver,correlationId: req.id},);One flow declaration captures fail-fast validation, parallel hydration, idempotent early exit, conditional branching, retried external calls, transactional persistence, multi-event publishing, and a typed output shape — with full type-safe state threading and cooperative cancellation via ctx.signal. Add an opt-in durability store and the same flow survives a process crash without re-running completed steps.
The full guide lives at celom.github.io/prose:
- Getting started and core concepts
- API reference:
createFlow, flow builder, execution options, error types, observers, durability store - Guides: retries, timeouts & cancellation, transactions, events, parallel execution, conditional steps, sub-flows, durability, error handling, observability
- Runnable examples: order processing, order processing with durability, user onboarding
- Comparison — when to reach for Prose versus Temporal, Inngest, Effect, or XState
| Package | Description |
|---|---|
@celom/prose | Core workflow library — see the package README |
Prose ships with a built-in Model Context Protocol server that helps AI assistants write correct flow code. Add to your MCP client config:
{
"mcpServers": {
"prose": {
"command": "npx",
"args": ["-y", "@celom/prose", "mcp"]
}
}
}See the MCP guide for the tools, resources, and prompts the server exposes.
This is an Nx monorepo.
# install dependencies
npm install
# run tests
npx nx test prose
# build the library
npx nx build prose
# run the docs site locally
npx nx dev docsCreated and maintained by Carlos Mimoso.
MIT