DEV Community: Ivan Guerreschi

Install Podman on Fedora Linux

Ivan Guerreschi — Thu, 24 Mar 2022 14:10:33 +0000

Podman is a daemonless container engine for developing, managing, and running OCI Containers on your Linux System.

Podman is installed by default in Fedora Linux and Fedora Silverblue. If not, use this command:

sudo dnf install podman

First example:

podman pull hello-world podman run hello-world

New Hello World! in C #

Ivan Guerreschi — Thu, 17 Dec 2020 16:14:24 +0000

With .NET Core 5 the famous Hello World becomes even easier

System.Console.WriteLine("Hello World!");

Create Rails project

Ivan Guerreschi — Tue, 15 Dec 2020 16:32:17 +0000

Simple script for create Rails project

https://github.com/ivanGuerreschi/CreateRailsProject

Edit the script as you wish

Using bundle exec with Flycheck in Emacs

Ivan Guerreschi — Thu, 26 Nov 2020 19:54:33 +0000

Create a .dir-locals.el file in the project root and
edit the file with this code in Emacs Lisp

((ruby-mode . ((eval . (setq-local flycheck-command-wrapper-function
  (lambda (command)
    (append '("bundle" "exec") command)))))))

Example recursion in Clojure

Ivan Guerreschi — Thu, 02 Jul 2020 14:28:53 +0000

Recursion of the perimeter of a square

Given one side find the perimeter of each square
f(n) = 4 * n + f(n - 1)

(ns recursion.core
  (:gen-class))

(defn -main
  [& args]  
  (defn f [n]
    (if (= n 1)
      4
      (+ (* 4 n) (f (dec n)))))
  (println (f 4)))

Configure Emacs for Clojure

Ivan Guerreschi — Wed, 17 Jun 2020 15:15:43 +0000

Basic configuration to start using Clojure with Emacs

Create the init.el configuration file

Open a terminal and create a directory: mkdir ~/emacs.d
Enter the newly created directory: cd emacs.d
Create file: touch init.el

Install MELPA repository

Editing file: emacs init.el

(require 'package)
(let* ((no-ssl (and (memq system-type '(windows-nt ms-dos))
                    (not (gnutls-available-p))))
       (proto (if no-ssl "http" "https")))
  (when no-ssl (warn "\
Your version of Emacs does not support SSL connections,
which is unsafe because it allows man-in-the-middle attacks.
There are two things you can do about this warning:
1. Install an Emacs version that does support SSL and be safe.
2. Remove this warning from your init file so you won't see it again."))
(add-to-list 'package-archives (cons "melpa" (concat proto ://melpa.org/packages/")) t)
  ;; Comment/uncomment this line to enable MELPA Stable if  desired.  See `package-archive-priorities`
  ;; and `package-pinned-packages`. Most users will not need or want to do this.
  ;;(add-to-list 'package-archives (cons "melpa-stable" (concat proto "://stable.melpa.org/packages/")) t)
  )
(package-initialize)

With this code we have installed the MELPA repository, this repository contains many packages for expanding Emacs

Install CIDER

CIDER is the Clojure(Script) Interactive Development Environment that Rocks!

(use-package cider
  :ensure t)

Save the file C-x C-s close C-x C-c and restart Emacs

This is a basic configuration for using Clojure with Emacs

Install Leiningen

Ivan Guerreschi — Tue, 16 Jun 2020 17:09:12 +0000

Install Leiningen using SDKMAN

First install SDKMAN

If you use Ubuntu maybe you will need to install the curl package: sudo apt install curl
Open new terminal and enter: curl -s "https://get.sdkman.io" | bash
always after from the terminal: source "$HOME/.sdkman/bin/sdkman-init.sh" or open new terminal
Check if it has been installed correctly: sdk version

Now install Java

To install the latest stable version of Java: sdk install java
To verify that Java has been correctly installed: java -version

Install Leiningen

Now you can finally install Leiningen with the command: sdk install leiningen
lein version to check if it has been installed

First post, first try Clojure

Ivan Guerreschi — Sat, 13 Jun 2020 13:54:27 +0000

I explore the Clojure language

To program in Clojure i use Emacs with Cider, Lein and Ubuntu 20.04 LTS Operating System

Let's create a new project with the command: lein new app hello-world

Open the file hello-world/src/hello_world/core.clj with Emacs
The file contains the classic Hello World program

(ns hello-world.core
  (:gen-class))

(defn -main
  "I don't do a whole lot ... yet."
  [& args]
  (println "Hello, World!"))

To run the program: lein run

This is the result:
Hello, World!