João Santiago jcpsantiago

ClojureScript REPL Workflow

Short write up on using REPL when developing UIs in ClojureScript.

Hot-reload on save or Eval in REPL?

Everyone's standard approach to hot-reloading is to use a tool (Figwheel or shadow-cljs) that reloads changed namespaces automatically. This works really well: you change the code, the tool picks up changed files, compiles namespaces and dependants, notifies REPL client which then pulls in compiled changes, and re-runs a function that re-renders UI.

The other approach is to use ClojureScript's REPL directly and rely only on eval from the editor. This more or less matches Clojure style workflow. This approach might be useful when you don't want tools overhead or hot-reloading becomes slow for you or you just used to this style of interactions. Also changing code doesn't always mean that you want to reload all the changes. On the other hand it is very easy to change a couple of top-level forms and forget to eval one of them.

gif-from-tweet

There are so many great GIFs out there and I want to have copies of them. Twitter makes that harder than it should be by converting them to MP4 and not providing access to the source material. To make it easier, I made a bash pipeline that takes a tweet URL and a filename, extracts the MP4 from that tweet and uses ffmpeg to convert back to GIF.

Dependencies

ffmpeg
- macOS: brew install ffmpeg
- Ubuntu/Debian: apt install ffmpeg

	address;name;type;postcode;phone;email;educational;topics;languages;lat;lon
	Wartenburgstr. 7;Ev. Kirchengemeinde Jesus-Christus;Kindertagesstätte;10963;030216 30 87;[email protected];;;;52.49654;13.38089
	Wilhelmstr. 15;Trauminsel e.V.;Eltern-Initiativ-Kindertagesstätte;10963;030-25923697;[email protected];Situationsansatz;Ästhetische Bildung (Musik und Kunst), Gesundheit, Interkulturelle Pädagogik, Körper und Bewegung;deutsch - arabisch;52.50275;13.38865
	Wilhelmstr. 54;Kinder im Kiez gGmbH;Kindertagesstätte;10963;030208 92 14;[email protected];;;;52.4985969;13.3783562
	Dessauer Str. 27;Orte für Kinder GmbH;Kindertagesstätte;10963;0302639 7930;[email protected];;;;52.50369999999999;13.3791
	Hornstr. 13;EMMA gemeinnützige GmbH;Kindertagesstätte;10963;03054849986;[email protected];Montessori-Pädagogik;;;52.49478;13.38017
	Wilhelmstr. 3;Trauminsel e.V.;Eltern-Initiativ-Kindertagesstätte;10963;030-25938954;[email protected];Situationsansatz;Ästhetische Bildung (Musik und Ku

	(def ■ '■)
	(def ▲ '▲)
	(def ● '●)

	(first [● ■ ▲]) ; ●
	(second [● ■ ▲]) ; ■
	(nth [● ■ ▲] 2) ; ▲
	(rest [● ■ ▲]) ; (■ ▲)
	(last [● ■ ▲]) ; ▲
	(butlast [● ■ ▲]) ; (● ■)

	#!/usr/bin/env bb
	#_" -- mode: clojure; --"
	;; Based on https://github.com/babashka/babashka/blob/master/examples/image_viewer.clj

	(ns http-server
	(:require [babashka.fs :as fs]
	[clojure.java.browse :as browse]
	[clojure.string :as str]
	[clojure.tools.cli :refer [parse-opts]]
	[org.httpkit.server :as server]

	#_( ;; Allow this script to be executed directly
	"exec" "bb" -o "--classpath" "." "$0" "$@"
	)

	;; Copyright © 2020, Malcolm Sparks

	;; Permission is hereby granted, free of charge, to any person obtaining a copy
	;; of this software and associated documentation files (the “Software”), to deal
	;; in the Software without restriction, including without limitation the rights
	;; to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

	(ns scrape
	(:require [babashka.pods :as pods]
	[clojure.walk :as walk]))

	(pods/load-pod "bootleg") ;; installed on path, use "./bootleg" for local binary

	(require '[babashka.curl :as curl])

	(def clojure-html (:body (curl/get "https://en.wikipedia.org/wiki/Clojure")))

	<html>
	<head>
	<link href="https://cdnjs.cloudflare.com/ajax/libs/prism/1.17.1/themes/prism-tomorrow.min.css" rel="stylesheet" />
	</head>
	<body>
	<script src="https://cdnjs.cloudflare.com/ajax/libs/prism/1.17.1/components/prism-core.min.js"></script>
	<script src="https://cdnjs.cloudflare.com/ajax/libs/prism/1.17.1/plugins/autoloader/prism-autoloader.min.js"></script>
	<pre>
	<code class="language-clojure">
	(defn foo []

	(ns appliedsciencestudio.covid19-clj-viz.repl
	(:require [clojure.string :as string]
	[hickory.core :as hick]
	[hickory.select :as s]))

	;;;; Scraping data

	(def wiki-page
	"We want this data, but it's only published as HTML."
	(slurp "https://en.wikipedia.org/wiki/List_of_countries_by_hospital_beds"))

	# Takes an ordered vector of numeric values and returns a small bar chart made
	# out of Unicode block elements. Works well inside dplyr mutate() or summarise()
	# calls on grouped data frames.

	sparkbar <- function(values) {
	span <- max(values) - min(values)
	if(span > 0 & !is.na(span)) {
	steps <- round(values / (span / 7))
	blocks <- c('▁', '▂', '▃', '▄', '▅', '▆', '▇', '█')
	paste(sapply(steps - (min(steps) - 1), function(i) blocks[i]), collapse = '')