GitHub - functionalland/functional-http-server: A simple HTTP server inspired by Express and in tune with Functional Programming principles in JavaScript for Deno.

A simple HTTP server inspired by Express and in tune with Functional Programming principles in JavaScript for Deno.

Simple HTTP server
Routing
Server
Utilities

Usage

Functional HTTP Server is optimized to write elegant and powerful point-free functions. This example uses the Ramda library - for simplification - but you should be able to use any library that implements the Fantasy-land specifications.

This example showcase how to create an endpoint handler for POST /hoge that writes to a local file and to Redis simultaneously the content of the request's body and, replies with 201.

import Task from "https://deno.land/x/[email protected]/library/Task.js";
import {
  decodeRaw,
  encodeText,
  evert,
  safeExtract
} from "https://deno.land/x/[email protected]/library/utilities.js";
import File from "https://deno.land/x/[email protected]/library/File.js";
import Request from "https://deno.land/x/[email protected]/library/Request.js";
import Response from "https://deno.land/x/[email protected]/library/Response.js";
import { fetch } from "https://deno.land/x/[email protected]/library/browser_safe.js";
import { writeFile } from "https://deno.land/x/[email protected]/library/fs.js";
import RedisRequest from "https://deno.land/x/[email protected]/library/RedisRequest.js";
import { $$rawPlaceholder } from "https://deno.land/x/[email protected]/library/Symbol.js";
import { executeRedisCommandWithSession } from "https://deno.land/x/[email protected]/library/client.js";

import { handlers, route } from "https://deno.land/x/[email protected]/library/route.js";
import startHTTPServer from "https://deno.land/x/[email protected]/library/server.js";

startHTTPServer(
  { port: 8080 },
  route(
    handlers.post(
      "/hoge",
      compose(
        map(_ => Response.Created({ 'content-type': "text/plain" }, encodeText("Created!"))),
        converge(
          (...tasks) => evert(Task, tasks),
          [
            compose(
              executeRedisCommandWithSession({ port: 6379 }),
              concat(RedisRequest("SET", new Uint8Array([]), [ "hoge", $$rawPlaceholder ]))
            ),
            compose(
              writeFile({}),
              concat(File.fromPath(`${Deno.cwd()}/hoge`))
            )
          ]
        )
      )
    )
  )
);

const container = await fetch(
  Request(
    {
      headers: {
        'accept': 'text/plain',
        'content-type': 'text/plain'
      },
      method: 'POST',
      url: 'http://localhost:8080/hoge'
    },
    encodeText("Hello, Hoge!")
  )
).run()

const response = safeExtract("Failed to unpack the response", container);

assert(Response.Success.is(response));
assertEquals(response.headers.status, 201);

server.close();

Simple HTTP server

The fastest way to start a HTTP server is to use the startHTTPServer function. The function takes two arguments; the first argument is the options, and the second is a unary function that takes a Request and return a Task of a Response.

import Task from "https://deno.land/x/[email protected]/library/Task.js";
import Response from "https://deno.land/x/[email protected]/library/Response.js";
import startHTTPServer from "https://deno.land/x/[email protected]/library/server.js";

startHTTPServer({ port: 8080 }, request => Task.of(Response.OK({}, request.raw)));

You can test this simple server by executing it your file

$ deno run --allow-net server.js

$ curl localhost:8080 -d "Hello, Hoge!"
> Hello, Hoge!

Routing

The main routing tool that comes bundled with this library is conveniently called route. It takes a non-zero number of arguments which are defined by a pair of functions. The first function of the pair is used to assert whether or not to execute the second function. The assertion function takes a Request and return a Boolean, the handling function takes a Request and must return a Task of a Response.

import Task from "https://deno.land/x/[email protected]/library/Task.js";
import { encodeText } from "https://deno.land/x/[email protected]/library/utilities.js";
import Response from "https://deno.land/x/[email protected]/library/Response.js";
import { route } from "https://deno.land/x/[email protected]/library/route.js";

startHTTPServer(
  { port: 8080 },
  route(
    [
      request => request.headers.method === 'GET',
      _ => Task.of(Response.OK({ 'content-type': 'text/plain' }, encodeText("Hello, Hoge!")))
    ]
  );
);

Routing handlers

Because the pattern is common, this library also offers a collection of handler that automatically creates the assertion function. Each handler takes a String or a RegExp and a unary function.

import Task from "https://deno.land/x/[email protected]/library/Task.js";
import { encodeText } from "https://deno.land/x/[email protected]/library/utilities.js";
import Response from "https://deno.land/x/[email protected]/library/Response.js";
import { handlers, route } from "https://deno.land/x/[email protected]/library/route.js";

startHTTPServer(
  { port: 8080 },
  route(
    handlers.get('/', _ => Task.of(Response.OK({ 'content-type': 'text/plain' }, encodeText("Hello, Hoge!"))))
  )
);