Examples

Annotated tours of the runnable packages under examples/. Three of them model one small checkout between them, each showing a different job unthrown does; the fourth stands alone.

Unlike the snippets elsewhere in this guide, this code compiles and is covered by tests. There is no database and no server to start:

git clone https://github.com/btravstack/unthrown.git
cd unthrown
pnpm install
pnpm turbo run test --filter="@unthrown/example-*"
pnpm turbo run typecheck --filter="@unthrown/example-*"

Checkout domain

The error union, Do/bind sequencing, exhaustive matching, and the defect channel — a thrown payment-provider outage becomes a Defect, never an Err a caller might mistake for a modelled outcome.

Checkout persistence

@unthrown/prisma on in-memory SQLite: why a read infers E = never (absence is null; a database that will not answer is a defect) and a write carries only the P-codes a caller would actually branch on.

Checkout API

The edge: placeOrder served over oRPC with @unthrown/orpc — one exhaustive mapErrCases, a handler with no try/catch, a provider outage that collapses to INTERNAL_SERVER_ERROR instead of an unhandled rejection, and why oRPC's own input validation is a separate concern from E.

Existing error types

The adoption case, with no TaggedError anywhere: a codebase that already has an error convention — a kind-discriminated class hierarchy, a plain code union from a generated client, and untagged third-party classes — wired to Result without rewriting any of it.

Why these exist as packages rather than snippets

Every fenced block in the rest of this guide is written by hand. It is checked by review and nothing else, so it can drift from the library without any build noticing.

These cannot. They are workspace packages: they typecheck, their specs run in CI, and they consume unthrown and its satellites through their real published entry points rather than a path alias. If the library changes underneath them, something goes red.