Node.js 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.

With Marble.js you can map Node.js streams directly through HttpEffectResponse body attribute which will be piped internally as client response.

import { r, combineRoutes } from '@marblejs/http';
import { requestValidator$, t } from '@marblejs/middleware-io';
import { readFile } from '@marblejs/core/dist/+internal';
import { map } from 'rxjs/operators';
import * as fs from 'fs';
import * as path from 'path';

const validateRequest = 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 })),

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