Daniel Petranek dpetranek

As per Jakub Holý's great Awesome Babashka: Parse & produce HTML and SQLite post, you can use the retrogradeorbit/bootleg pod to get Hickory (HTML to Hiccup parser) in Babashka. However, if you're on NixOS, you're going to get yelled at when you try to start a REPL:

: bb-playground; bb repl                                                                                                                                                                       
Downloading pod retrogradeorbit/bootleg (0.1.9) 
Successfully installed pod retrogradeorbit/bootleg (0.1.9)                                                                                                                                     
Exception in thread "main" java.io.IOException:

task dependencies

Let's say you're writing a project management app. A user will have a bunch of tasks to do and each task might depend on other tasks. Your challenge is to write a function that, given tasks and dependencies, gives at least one order for the tasks such that no task is done before its dependencies are done.

(def tasks [:clean-breakfast :shoes :socks :cook-breakfast :eat-breakfast])

(def dependencies [[:socks :shoes] ;; socks come before shoes; shoes depend on socks
                   [:cook-breakfast :eat-breakfast] ;; cooking comes before eating
 [:eat-breakfast :clean-breakfast]])

Building a blockchain, assisted by Clojure spec

In an effort to gain at least a superficial understanding of the technical implementation of cryptocurrencies, I recently worked my way through "Learn Blockchains by Building One" using Clojure.

This was a good chance to experiment with using spec in new ways. At work, we primarily use spec to validate our global re-frame state and to validate data at system boundaries. For this project, I experimented with using instrumentation much more pervasively than I had done elsewhere.

This is not a guide to spec (there are already many excellent resources for this). Rather, it's an experience report exploring what went well, what is still missing, and quite a few unanswered questions for future research. If you have solutions for any of the problems I've presented, please let me know!

You don't need to know or care about blockchains to understand the code be

Host Your Site Under Your Domain on IPFS

This is a step-by-step tutorial for hosting your website under your domain on IPFS, from zero, on a DigitalOcean Ubuntu 16.04.3 x64 Droplet (i am using the $10 variant with 2GB RAM).

Install IPFS

Log in as root.

First, make sure the system is up to date, and install tar and wget:

	#!/bin/sh

	command="${*}"
	printf "Initialized REPL for `%s`\n" "$command"
	printf "%s> " "$command"
	read -r input
	while [ "$input" != "" ];
	do
	eval "$command $input"
	printf "%s> " "$command"

	QTabBar,
	QTabBar::tab
	{
	font-family: "Noto Sans";
	font-size: 11px;
	height: 16px;
	padding: 2px;
	border: 0px;
	border-bottom: 3px solid palette(dark);
	background-color: palette(dark);