Lykn

HTTP Servers

Deno Native: Deno:serve

(Deno:serve (obj :port 8080)
  (fn (:any request)
    (bind headers (new Headers))
    (headers:set "Content-Type" "text/plain")
    (new Response "Hello from Lykn!" (obj :headers headers))))

Deno.serve({port: 8080}, (request) => {
  const headers = new Headers();
  headers.set("Content-Type", "text/plain");
  return new Response("Hello from Lykn!", {headers});
});

One function. Web API Request and Response objects — the same standard web platform APIs the browser uses. No legacy callback interface.

With Routing

(Deno:serve (obj :port 8080)
  (async (fn (:any req)
    (bind url (new URL req:url))
    (match url:pathname
      ("/api/users" (await (handle-users req)))
      ("/api/health" (new Response "ok"))
      (_ (new Response "Not Found" (obj :status 404)))))))

match on the pathname provides clean routing. Each arm returns a Response.

A Note on HTTP Headers

Lykn keywords undergo camelCase conversion (:content-type → contentType), but HTTP headers use their own casing (Content-Type). Use the Headers constructor with string keys for headers instead of obj with keywords.

Node.js Compatibility

(import "node:http" (create-server))

(bind server (create-server (fn (:any req :any res)
  (set! res:status-code 200)
  (res:set-header "Content-Type" "text/plain")
  (res:end "Hello from Lykn!"))))

(server:listen 8080)

Deno:serve is dramatically simpler — one function vs a multi-step callback. Use node:http only when porting existing Node.js code.