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Today we extended the project from week 11 and created a base template. This base template contains an AnchorPane, where FX-elements from other FXML files can be appended to. Therefore, we can change on click our UI and load new elements to it.

// src/main/java/Main.java

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;

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We played around with clojure.spec and followed the post Interactive Development with clojure.spec.

In the beginning, we started to get to know the semantics of clojure.spec and looked at some specs. After this, we solved the codebreaker-example and successfully defined some specs for it.

REPL Session from Clojure Meetup Düsseldorf, Germany, 6th July 2017

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Let's play around with a postgres database and Clojure. To query and insert a database, we need to create one:

docker run --rm --name eventdb -e POSTGRES_PASSWORD=foo -e POSTGRES_USER=foo -e POSTGRES_DB=foo -d -p 5432:5432 postgres

This creates a postgres database named foodb, with password, user and tablename also being foo. Ports are exposed to our local machine and we can access the database at localhost:5432.

Now, we need to connect to the database and create a table, which can be queried and filled with korma. You can use a library to do this, but for a minimal example this is not necessary:

user@host ~ % docker exec -it eventdb su postgres -c psql

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Just thought about a FizzBuzz solution written in frege which I saw on a meetup. This solution does not need any conditionals and is completely lazy, which is why I like this solution so much.

The rules are as follows:

• print all numbers from 1 to n, but...
  • replace all numbers, which are smoothly divisible by 3, with "fizz"

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I have a huge amount of data in an Excel-Sheet and want to get some statistics of it. Since I am only using LibreOffice, which is not very comfortable, and I am really loving web-techniques to build UIs / visualizations, I decided to use devcards and ClojureScript with React.js to build some Charts.

This is inspired by this gist, but I want to use it with om.next and devcards, which is why I am writing this gist.

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Spacemacs

In Spacemacs wird die Philosophie verfolgt, dass es nicht den besten Editor gibt, sondern man bemüht sich die besten Funktionen von vim und emacs zu vereinen.

Dabei sind beide Keymappings möglich, vim oder emacs. Oder einfach beides (hybrid-mode). Wenn der emacs-mode gewählt wurde beim Keymapping, so sind die Tastaturkürzel mit M-x (also die Tasten ALT + x) oder M-m meistens zu erreichen. Unter vim-mode finden

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Clojure Meetup Juni 2018

Wir haben ein wenig in der REPL gespielt und dabei ist dieser Code entstanden:

(ns intro.core)

(defn spielregeln
  "I don't do a whole lot."
 [x]

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A Docker Multistage Build reduces the complexity of a production image to a minimum. Since it is very easy to build jars from Clojure applications, we can just use an JRE to bring it to production.

Let's create a sample project using the app template with Leiningen:

lein new app foo
cd foo

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Inspired by this Gist and @coryodaniel's solution, I put the script inside a babashka script, called pdf-like-fax.clj:

#!/usr/bin/env bb
(defn pdf-like-fax [input output]
  (let [sign (rand-nth ["+" "-"])
        rotation (rand-int 1000)
        cmd (format "convert -density 150 %s -rotate %s0.%s -attenuate 0.4 +noise Multiplicative -attenuate 0.03 +noise Multiplicative -sharpen 0x1.0 -colorspace Gray %s" input sign rotation output)
 prepared-cmd (str/split cmd #" ")]

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To cache the layer containing the dependencies from your Clojure project, you can execute a command without starting a REPL. This downloads all common dependencies, which are then be cached.

For example:

FROM clojure:openjdk-14-tools-deps-alpine

# Cache and install Clojure dependencies
COPY deps.edn .