Streams are collections of data that might not be available all at once, and they don’t have to fit in memory. This makes streams really powerful when working with large amounts of data, or data that’s coming from an external source one chunk at a time.

Since Marble.js v2.1 you can send Node.js streams directly through HttpEffectResponse body attribute which will be piped internally as client response.

import { r, combineRoutes, use } from '@marblejs/core';
import { requestValidator$, t } from '@marblejs/middleware-io';
import { readFile } from '@marblejs/core/dist/+internal';
const getFileValidator$ = requestValidator$({
params: t.type({ dir: t.string })
const getFile$ = r.pipe(
r.useEffect(req$ => req$.pipe(
map(req => req.params.dir),
map(dir => fs.createReadStream(path.resolve(STATIC_PATH, dir))),
map(body => ({ body }))