Ahmed Hassan ahmed1hsn

Advance the support of Scala.js in Dotty, a tutorial

Dotty contains preliminary support for Scala.js under the flag -scalajs. Or rather, it contains the infrastructure for preliminary support. It is far from being actually usable, but this is where you can help!

This small tutorial walks you through a few steps that you can do to further the support of Scala.js in Dotty. Even if you do not typically contribute to a compiler, this can be your chance. It is not very difficult, given that there already exists an extensive test suite, as well as a working implementation for scalac.

Offline MDN Docs

If you want resources offline to learn about programming and web technologies MDN is for you! and I recommend to use MDN over w3school because w3school is outdated.

full tarball download

Download it offline (2.1gb) at https://mdn-downloads.s3-us-west-2.amazonaws.com/developer.mozilla.org.tar.gz

Third-party toolsSection

Dependency Injection in Functional Programming

There exist several DI frameworks / libraries in the Scala ecosystem. But the more functional code you write the more you'll realize there's no need to use any of them.

A few of the most claimed benefits are the following:

Dependency Injection.
Life cycle management.
Dependency graph rewriting.

Thread Pools

Thread pools on the JVM should usually be divided into the following three categories:

CPU-bound
Blocking IO
Non-blocking IO polling

Each of these categories has a different optimal configuration and usage pattern.

	import org.scalatest.{FreeSpec, Matchers}

	class Filter2FilterTest extends FreeSpec with Matchers with ZioTestSupport {

	case class JsonErr()

	case class JsonReq()

	case class JsonRes()

	(ns deployer
	(:require [clojure.tools.deps.alpha :as deps]
	[clojure.tools.deps.alpha.reader :as reader]
	[clojure.java.io :as io]
	[clojure.string :as string])
	(:import (java.security MessageDigest)
	(com.jcraft.jsch JSch)
	(java.net URI)))

	(def hex-alphabet (vec "0123456789ABCDEF"))

	(defn relate [& pairs]
	(assert (even? (count pairs)) "relate requires an even number of arguments")
	(->> pairs
	(partition 2)
	(map (fn [[k vs]] (map #(hash-map k %) vs)))
	(apply map merge)))


	(defn matches-specmap? [specmap m]
	(reduce-kv

	(ns specter-idea
	(:require [com.rpl.specter :as specter :refer [setval ALL
	NONE multi-path
	selected?
	pred
	]]))

	(def data ;; only x and y are allowed
	[{:name "x" :rels ["x" "y"]} ;=> fine, keep as is
	{:name "y" :rels ["x" "y" "z"]} ;=> keep only allowed rels: {:name "y" :rels ["x" "y"]}

	(require '[datomic.api :as d])

	(d/create-database "datomic:mem://counter-example")
	;=> true
	(def c (d/connect "datomic:mem://counter-example"))
	;=> #'user/c

	;; The essential features of creating and using an auto-increment counter in datomic:
	;;
	;; 1. A counter entity must store the current value and a nonce.

	{:deps
	{org.clojure/clojure {:mvn/version "1.9.0"}
	com.datomic/datomic-free {:mvn/version "0.9.5697"}}}