fp-codemod

bun add -d typescript @stopcock/fp-codemod
bunx stopcock-fp-codemod --check src
bunx stopcock-fp-codemod --write src

Dry-run is the default. --check is suitable for CI, --write applies safe mechanical edits, and --json returns a machine-readable summary.

The codemod rewrites replaced subpaths, splits legacy root namespaces into focused imports, moves named Option, Result, Guard, and Function exports, preserves aliases and formatting style, and updates compatible match handlers. It emits explicit diagnostics instead of guessing when a migration changes semantics.

import { transformSource } from '@stopcock/fp-codemod'
import { runCodemod } from '@stopcock/fp-codemod/node'

const result = transformSource(sourceText, 'example.ts')
const summary = await runCodemod(['src'], { write: true })

TypeScript 7 is a peer dependency so the transform uses the same compiler API as the project being migrated.