Official packages#

The Velt repository ships four packages next to the standard library: an HTTP server and three database drivers. A program imports one by its package name once its package.vlt lists it in dependencies.

Package	What it is
http-server	An HTTP/1.1 and HTTP/2 server written in Velt: `serve` with web-standard `Request` → `Response` handlers, HTTPS, streaming, graceful stops and WebSockets.
sqlite	Embedded SQLite with a synchronous API close to better-sqlite3, and a read-only SQLite engine written in Velt.
postgres	A PostgreSQL client close to node-postgres: connections, a pool, transactions, batches, `COPY`.
redis	A Redis client close to ioredis: commands, pipelines, transactions and pub/sub on one multiplexed connection.

Why they are not std#

The standard library is the core every program can count on: files, processes, networking, fetch and the web types, encodings, collections, tasks. A server and a database driver are libraries, and each of these packages is written on public std APIs only, the ones any package can use: Request, Response and their server API in velt/net/http, velt/net/http/h2, velt/dev for the graceful stop under velt dev, typed rows from velt/db, and velt/native for the Rust half of a driver. So anyone can write another server or driver the same way. They live in the Velt repository's packages/.

Depending on a package#

Add the package to dependencies in package.vlt: from the Velt repository on GitHub as a git dependency, or from a local checkout as a path dependency. velt install fetches it and pins it in velt.lock.json:

package.vlt

import type { Package } from "velt/package";

export const pkg: Package = {
  name: "app",
  version: "0.1.0",
  dependencies: {
    "http-server": { git: "https://github.com/velt-lang/velt", branch: "main", path: "packages/http-server" },
    // Or a local checkout of the repository:
    // "http-server": { path: "../velt/packages/http-server" },
  },
};

src/main.vlt

import { serve } from "http-server";

await serve({ port: 8080 }, (req: Request): Response => new Response("hello"));

velt new <name> --template api (and --template websocket) writes the http-server dependency for you, at the release tag of the velt that made the project.

sqlite, postgres and redis include a Rust crate, their native code. A path dependency builds it with cargo the first time, so it needs a Rust toolchain; a git dependency builds it only when you allow that with VELT_NATIVE_FROM_SOURCE=1, since the build runs the package's build scripts. A package published to a registry carries prebuilt libraries, so its users need no Rust (packages with native code). Each package's page has its exact entry.