felixfoertsch.de

Apple Colors in SCSS

2020-08-05T00:00:00+00:00

Colors have a big impact on how software looks. Personally, I think macOS and iOS are beautiful and the colors are very well selected. Since I am not a designer, but I want to understand why these systems always looks so good, I started designing this website using the Apple colors. The first step I took was creating variables for the Apple colors from the Human Interface Guidelines (iOS/macOS).

I published them on GitHub as gists so you can use them, too. It’s just the raw variables; but I could not find them anywhere else in this SCSS form. Gist macOS-colors-dark.scss, macOS-colors-light.scss, iOS-colors-dark.scss, iOS-colors-light.scss.

Ideas

2020-08-04T00:00:00+00:00

Many people have ideas. Ideas are not special. What makes and breaks an idea is its realization and/or implementation. Here are some of my product ideas. Implement them, if you like them! Then send me an email to show them to me, please. 😁

Product Ideas

Flatpen: Pens have a problem. They are round and stiff and that makes them harder to carry around. The idea: Create a pen that uses regular pen mines, but folds flat so it can be put inside of a notebook without making it wobble.

Process Visualization with Z-Layers: Processes are an important part of business development and optimization. Their visualization is important for communicating them. Most process visualization software is clunky to use. Finding the right layer of abstractions with processes is hard by default – software should make it easier. This has to be a combined solution: From the editor to the reader. The core idea is using Z-layer zooming to make it more intuitive (e.g. pinching in mobile and tablet apps).

Magic Handshake: Create a system that supports favors. Being in the system opens you doors, because you know someone. Like an exclusive club.

10 Minute Mentor: Finding is a mentor is difficult. Make it easier.

Sane Games: Create a list of games that are sane: no IAP, no psycho abuse, etc.

Web App Ideas

Sign-up: Create an event where people can sign up really easily. Like Raid Helper, but generalized.

WOOP: PWA that implements the GROW or WOOP mental model.

Predefined Workflow Builder/Checklister/Show the Way: Many task in modern life follow step-by-step processes. It is really inefficient that everybody has to learn them individually. It should be easy to download a pre-created checklist for a specific task and then succeed with just following this checklist. E.g. “How to do a product launch” –> Step 1: Do X. Step 2: Do Y., “How to learn JavaFX” –> etc. Specialised Version of this could be a “You should app”. A collection of things everybody should do and/or have. Have a bank account, have insurance, etc.

GitHub Contributions for Everything: GitHub Contributions are awesome. They give a quick and intuitive overview about progress. Create a way that allows tracking everything like this.

Applicant Oriented Applications: Applications are awful for the applicant. They are at the mercy of organizations. They have to send in all their information and then they have to wait. And they have to do that multiple times. Use different interfaces, create different formats, and so on. It should be easier.

Make it very easy to donate to a good cause/org: One click donations. It is not easy to set up donations in Germany. There is a lot of hassle involved with creating receipts etc. This should be super easy for the associated organizations and should allow integrated systems like PayPal and Stripe for payments.

Local Twitter: It’s not always easy to know what’s happening around your. Make an app that makes it really easy to know what public events are happening right now around you. Concert? Demonstration? Check and know.

Gamekey Exchange: Enable people that buy things like humble bundle to trade their unused keys with each other.

Computer and Phone App Ideas

On time: Calendar integration that allows one click information to others, if you are on time or not.

Hierarchical Documentation: Documentation of software is often flat, even though hierarchies are at the core of many projects. Tools should display hierarchies to make it easier to quickly grasp software libraries.

Moderator Toolbox: Organizing groups is hard. Make using speech lists, protocols, etc. easy to do.

Cadence and Heartbeat Music: Generate electronic music (e.g. with AI) and use the heartbeat sensor of the Apple Watch attach it to the cadence and/or heart rate of the person.

Vaccination Card: There is a yellow book that helps track vaccinations. Make one that’s on your phone.

Walk the City: Exploring a city is awesome. Make an app that tracks all routes/streets you have already been to on the map to facilitate walking every road once.

Checkpoints: Create a system that allows people with bad time management to tell an accurate prediction on when they’ll get somewhere. Use map data and checkpoints to find out the time.

Color Clipboard: Monitor clipboard and store Hex codes. Give a nice UI to create palettes, etc.

Kontakte: Create a Tinder-like interface to clean-up contacts: Keep, delete, edit. Have a nice and easy way to add notes and tags. Potentially: Add whitelist/blocklist.

Business Plan Archive: Like ideas business plans have way less value than people think. Put them in the public domain.

Track a Thing: App that has a unified interface to track things very easily. Did a run: Track. How many days since you last called your mother: Track. Is your Doner bigger or smaller than average: Track.

Single Player Raider (Game): A game where you do a 40-person raid, but you do it solo on your own terms.

Apps that already exist (or probably exists), but require better design, should not cost money or should be open source

Tiddlywiki for Mac
Anki for Mac
Twitch for Mac: mpv/IINA as player and chat on the bottom (native portrait mode)
Ebook reader for Mac: Books always adds the PDF/ePub to the library, which is not always required
Reddit but with a limit: Scrolling is unhealthy.
Archiver for Mac: Easy archiving of things. YouTube via youtube-dl, etc.
https://www.progressbarosx.com/
Ambience: Menu bar one-click music player for study/background music

Strategies from the Happiness Lab

2020-08-02T00:00:00+00:00

I love listening to podcasts while I am out running. The latest one I found is The Happiness Lab from and with Dr. Laurie Santos, a professor teaching at Yale. She looks at happiness scientifically and takes an active approach: You have it in your own hands to improve your happiness. The podcast discusses various strategies with various scientists and experts from their respective field.

This is a collection of these strategies you can employ; with the link to the corresponding episode for more information.

Meditate. You have probably heard about people recommending meditating a thousand times. Do it. Start with 1 minute every day. The research of the benefits seems to be overwhelming.
Sleep enough. Trivial. Humans need sleep. Get. Some. Make it a ritual to go to bed. Make the bed a sanctuary. No screens, no distractions. If you are lying in bed, you sleep. If you can’t sleep, leave the bed and try again later. You can combine the ritual with meditation (see above).
Remove choice. Being in control of and having to decide everything is exhausting. Remove unnecessary choices from your life. Have a big wardrobe? Reduce it and go minimal. Or to quote President Obama who always wore a white shirt and cycled through his suits: “Do you know how many decision I have to make throughout the day? You think I also want to decide what to wear?”
Coach yourself from the third person. The research suggests that you perform better and are happier, if you think about the challenges you are facing from a third person perspective. The key term is distancing. Distance yourself to get a clearer picture of what is going on. You can use personal distancing (use your name instead of “I”): “Felix knows what he is doing and has experience. Trust him.” You can use temporal distancing: “Felix has faced this threat before and came out successful.” You can use group distancing: “We are a strong society and can solve this challenge together.”
Connect with others. Even strangers. Modern life aims at removing all inconveniences. But it also removes social connections with other people. The example from the podcast is from the guy that invented the ATM. When there were still bank tellers, you had to wait in line – where you might have to interact socially – and had to interact with the teller. A person. Research suggests that happiness improves just by interacting with other people
Frame your emotions. When encountering an emotion, you have 5 seconds to decide how to react to it. Use different frames depending on the situation. Examples for these frames:
- The comedic frame Try to tell a joke about the situation.
- The future storytelling frame Live your life in a way so that your story, told truthfully, makes you look like the person you strife to be. Which story sounds better to you? The story about a miserable and frustrated person that gave up on the slightest problem or the story about the person that strongly and cleverly encounters the challenges life throws at her and masters these challenges while smiling.
- The stoic gods challenge frame Use stoic, imaginary gods as a psychological device: Every setback you face in life is a test these gods have designed to test you and your character. And you want and can prove to them that you are up to the challenge. The harder the challenge is, the more trust the gods have in you.
Practice negative visualization. Pause every once in a while during the day and think about what you could lose and how that would make you feel. Don’t dwell on these thoughts. Just let them flicker for a second. This aims at increasing your appreciation for the people and things you have in your life.

The Collection

2020-07-20T00:00:00+00:00

During my time on the Internet, I encountered many things. This post is a collection of the cool things. I will probably update it once in a while. Since I am living in Germany, some of the tips may not be useful for everyone. In order of coolness.

Web Services

Uberspace is a hosting provider. They offer a shared hosting experience that is a little bit more limited than a root server. However, their support is amazing and it’s a super good place to host for tinkerers and small projects. Highly recommended. Check out my Tutorials or the Uberlab for U7 for things you can do on your Uberspace!

Things I am using on Uberspace:

InvoicePlane: Simple invoicing software. Offers sending offers and invoices via email, too!
Matomao: Analytics software to avoid Google.
Redmine: Amazing project management solution.
Syncthing: File synchronisation alternative.

Tecspace is a hosting provider and domain registrar. I buy and manage my domains through their service. It is extremely cheap, costing only 2,50 EUR per year, if you have 10 or more domains. I love their admin interface. It is simple, behaves like a website should behave (no JavaScript shenanigans) and is very powerful.

Pinboard is a bookmarking service. It’s minimalistic, easy to use and offers an archiving service so you will never lose these good articles on the internet again.

Software

Pictures, Design, Illustrating

Affinity produces Affinity Designer and Affinity Photo. They are competitors to the popular Adobe Photoshop and Illustrator. These two programs are exceptional. You can do basically everything you can do with their Adobe counterparts, but they only cost 55 EUR each. No subscriptions, no recurring fees. The interface is polished and if you are an Adobe user you will be right at home. Quit Adobe today. Don’t let them milk you.

Appollo One is a really fast image viewer.

Random Apps

Sensei is a system monitoring app with a nice Mac compliant interface.

Mactracker is an app that lists all apple hardware and their specifications. No need to google for these things anymore.

Install Mailtrain on Uberspace 7

2020-07-19T00:00:00+00:00

This tutorial explains how to install Mailtrain on a Uberspace 7. Mailtrain is a self-hosted open-source (released under the GPL v3.0.) newsletter app built on top of Nodemailer. I am following the manual installation guide from the official Mailtrain repo and add some additional Uberspace infos. I contributed this guide to the Uberlab and earned my first Ubercup.

Installation

This guide uses Node.js version 12, which is the default on Uberspace 7 at at the moment.

Clone the GitHub repository:

[isabell@stardust ~]$ git clone git://github.com/Mailtrain-org/mailtrain.git
[isabell@stardust ~]$

Install the required dependencies:

[isabell@stardust ~]$ cd mailtrain
[isabell@stardust mailtrain]$ npm install --production
[isabell@stardust mailtrain]$

Configuration

Database Setup

Create a new database:

[isabell@stardust mailtrain]$ mysql -e "CREATE DATABASE ${USER}_mailtrain;"
[isabell@stardust mailtrain]$

Mailtrain Config

Copy the example config file:

[isabell@stardust mailtrain]$ cp config/default.toml config/production.toml
[isabell@stardust mailtrain]$

Update production.toml with your MySQL settings; look for the [mysql] block:

...

[mysql]
host="localhost"
user="isabell"
password="MySuperSecretPassword"
database="isabell_mailtrain"

...

Web Backend Config

Mailtrain is running on port 3000. Configure the server to respond to port 3000 using web backends:

[isabell@stardust ~]$ uberspace web backend set / --http --port 3000
[isabell@stardust ~]$

Supervisord Daemon Setup

Create ~/etc/services.d/mailtrain.ini with the following content:

[program:mailtrain]
directory=%(ENV_HOME)s/mailtrain/
command=env NODE_ENV=production /bin/node index.js
autostart=yes
autorestart=yes

If it’s not in state RUNNING, check your configuration.

Change the default admin credentials to prevent unauthorized access of your data!

Your Mailtrain installation should now be reachable on https://isabell.uber.space. Log in with the username admin and the password test.

Go to https://isabell.uber.space/users/account and change your email address as well as your password.

It is not possible to change the username in the GUI. If you want to change the default username `admin` to something else or add additional users, you have to do it directly in the database.

Finishing installation

Go to https://isabell.uber.space/settings. In the General Settings section change the Service Address (URL) to https://isabell.uber.space/.

In the Mailer Settings section change the

Hostname,

Port,

Encryption,

username,

password, and

test your settings by pressing the Button Check Mailer Config.

Uberspace does not allow mass mailings from their servers according to their House Rules. However, you can use Mailtrain as the admin interface for your mailing needs. Use the SMTP services from AWS SES, Sendgrid, Mailgun, etc. for the actual mailing.

Best Practices

Test the configuration by creating a new list and subscribing yourself to it.
Craft your campaign with love and dedication.
Don’t spam users that don’t want your newsletter.

Tested on Uberspace v7.7.0 with NodeJS v12 and MariaDB 10.3.23.

Collection of High Quality Swift Libraries

2019-03-25T00:00:00+00:00

Libraries are an important part of programming. However, there should be a really good reason, if you decide to use a library. And if you use one, it should be a good one. These are some from my collection:

JTAppleCalendar: Need a calendar view? Don’t roll your own.
Keychain: Have something that need secure storage, like a password? Put it in the keychain.
SPPermission: Your app needs permissions? Inform the user properly. It’s important.
SwiftDate: Handles all your date and time needs. Don’t roll your own.
WhatsNewKit: Welcome your new user like apple does.

Helper

SwiftyUserDefaults: A small wrapper around NSUserDefaults that makes the usage swifter.

Use the Pumping Lemma for Regular Languages

2019-02-23T00:00:00+00:00

This semester I finished my course about automata and languages. I learned a lot and it was really enjoyable. From this field, there was a question about the Pumping Lemma on the computer science subreddit. So naturally, if someone ask about a thing I know about, I’ll try to explain it as best as I can – repetition is key for retaining knowledge!

My Explanation

My original post on Reddit.

To understand the PL, we think about it in two steps. I’ll do it for the regular languages. You can do the same on your own for the context free languages. The idea is the same.

We create a visual model to understand what it is about.
We do a PL proof.

1. Creating a visual model in your mind.

Firstly, we have to keep in mind that we want to show that a language is not regular. Let’s reason a little bit more about regular languages:

Regular languages can be accepted by finite automata (FA). That means: if your language is regular, there is an FA that accepts this language.
To check, whether a word is accepted by an FA, you start in a state, start reading in letters of your word and follow the edges through the FA. If the whole word is read and we end up in a final state, the FA accepts the word.
But hold on a second! FA can also accept words that have more letters than we have states and edges. How can that be?! The answer: loops.
Now, given any regular language, we know that there is an FA that accepts it (this is a theorem).
That means: if we have a word, that has more letters than we have states, but is still accepted by our FA, we have to have a loop in our FA.
Think about it: we can repeat this loop as many times as we want and the FA would still accept words that are processed by going through the loop repeatedly. It has to!
This repeating of the loop is referred to as pumping a word up or down.

2. Doing a proof.

Now, secondly, you want to proof something using this lemma. Let’s start with the PL (really try to understand this line!):

L ∈ REG → ∃n ∈ ℕ ∀x ∈ L: |x| ≥ n ∃u, v, w: x = u ∘ v ∘ w, |v| ≥ 1, |uv| ≤ n ∀i ∈ ℕ: u ∘ vⁱ ∘ w ∈ L

I’ll break it down. Remember: This is a theorem. If you meet the conditions of the implication (part on the left), you now know that the part on the right is true.

L ∈ REG →: “Given a regular language, the following is true.”
∃n ∈ ℕ: “There is a natural number”
∀x ∈ L: |x| ≥ n: “For every word x that is in the language and longer than this natural number”
- Remember the argument with the loops from part 1. This just says: we now have a word that has more letters than we have states.
∃u, v, w: x = u ∘ v ∘ w, |v| ≥ 1, |uv| ≤ n: “You can split up the word x into three parts: u, v, w where the length of v is equal to or bigger than 1 and the length of u ∘ v is smaller than our natural number from before”
- Here we describe the loop in more detail. v is the part that we can pump, because there is a loop that processes v (and can thus process arbitrary iterations of v - or skip it altogether. And because u ∘ v is smaller than n, we didn’t need a loop until now. We only really need a loop, if our word has more letters than we have states!
∀i ∈ ℕ: u ∘ vⁱ ∘ w ∈ L: “If all the conditions before have been met, we can now pump v up or down and the resulting word is still in the language!”
- Since it is a loop, pumping doesn’t make a difference. If you go the loop a million times, the word is still in the language.

That’s it. Again, because it is proved, you know it’s true if all the conditions are met.

We want to use the lemma to show, that a language is not a regular language. Let’s have a look at the implication from above. Think about the left part of the implication (L ∈ REG) as A and the right part (∃n ∈ ℕ ∀x ∈ L: |x| ≥ n ∃u, v, w: x = u ∘ v ∘ w, |v| ≥ 1, |uv| ≤ n ∀i ∈ ℕ: u ∘ vⁱ ∘ w ∈ L) as B: A → B.

We can now do the following transformation:

A → B ≡ ¬B → ¬A

To pull in the negation on the right side of this transformation, all the quantifiers have to “flip around”. This means the sentence now looks like this:

∀n ∈ ℕ ∃x ∈ L: |x| ≥ n ∀u, v, w: x = u ∘ v ∘ w, |v| ≥ 1, |uv| ≤ n ∃i ∈ ℕ: u ∘ vⁱ ∘ w ∉ L → L ∉ REG

Again, this is still the Pumping Lemma. We didn’t change it, we just used an transformation for the implication that is equivalent. If you meet the conditions on the left, you know the sentence on the right is true.

Let’s use this on an example: Show that L = {aᵏ ∘ bᵏ | k ≥ 0} is not regular.

Take any number n.
Select a word with the requirement x ∈ L with |x| ≥ n. Your mathematical creativity is requested here! You need to pick a word that helps you show the rest of the conditions easily! We are going to pick: x = aⁿbⁿ. This is convenient, because it’s obvious that it is as least as long as n (n occurs twice in it as an exponent). The important property to note: there are exactly as many a as there are b in this word. So if we can pump it in a way, that this is not the case anymore, we are golden!
Now we have to look at all of the partitions x = uvw with the conditions |v| ≥ 1 and |uv| ≤ n. Since we have to look at all of them we just say: Let’s assume these conditions are met (we can now use them in the next step).
Pick an i that shows that u ∘ vⁱ ∘ w ∉ L. Let’s take i = 0.
- Since our word is aⁿbⁿ and one of the conditions is |uv| ≤ n, we know that uv can only consist of the letter a.
- And because we have the condition |v| ≥ 1, we also know that v has to contain at least one letter a.
- If we now remove this letter (or maybe its more than one letter, it doesn’t matter), the amount of letters a in the word x is now not equal to the amount of letters b in the word.
- Hence: Our word is not part of the language any more (u ∘ v⁰ ∘ w ∉ L), violating the PL.

This shows that L = {aᵏ ∘ bᵏ | k ≥ 0} is not a regular language.

Die Rechnung

2019-02-22T00:00:00+00:00

Die Rechnung ist eines der wesentlichsten Dokumente des Geschäftsverkehrs. Da sie ein formales Dokument ist, müssen einige Regeln eingehalten werden, damit eine Rechnung gültig ist und der Kunde bezahlen muss. Der Gesetzgeber hat eindeutig festgelegt, welche Angaben enthalten sein müssen (§ 14 UStG):

Der vollständige Name und die Anschrift des Rechnungssteller
Der vollständige Name und die Anschrift des Rechnungsempfänger
Die Steuernummer des Rechnungsstellers
Das Ausstellungsdatum
Eine eindeutig Rechnungsnummer
Die Menge und Art der gelieferten Leistung
Das Datum der Lieferung (auch wenn identisch mit oben!)
Der Netto-Betrag der Lieferung
Den anzuwendenden Steuersatz
Den anfallenden Steuerbetrag

iPad Gestures

2019-02-22T00:00:00+00:00

I did it! I bought an iPad and an Apple Pencil for christmas last year. I write a lot for my university classes and I didn’t like that I often had to cross out things on paper (because I wrote something down wrong) and had to write them again. I was not sure, if an iPad is the right device for me – but turns out it is. It is awesome. If you make a mistake, you erase it and write it again. Wrong sequence of your sentences? Just move them around. The notes come out awesome.

Additionally I learned a few gestures that are really useful:

Swipe with two fingers on the virtual keyboard to move cursor.
Tap and hold with two fingers to begin selecting, then move fingers to expand selection, OR
Tap once with two fingers to select single word.
Double tap with two fingers to select sentence.
Triple tap with two fingers to select paragraph.

While text is selected:

Swipe left/up with two fingers to move left selection handle.
Swipe right/down with two fingers to move right selection handle.
Tap once with two fingers to exit selection and return to cursor mode.

Blackhole

2019-02-21T00:00:00+00:00

This is a text I found on the internet and saved it. If anybody knows the source, please tell me, so I can give credit.

Blackhole

Imagine, just for a moment, that you are aboard a spaceship equipped with a magical engine capable of accelerating you to any arbitrarily high velocity. This is absolutely and utterly impossible, but it turns out it’ll be okay, for reasons you’ll see in a second.

Because you know your engine can push you faster than the speed of light, you have no fear of black holes. In the interest of scientific curiosity, you allow yourself to fall through the event horizon of one. And not just any black hole, but rather a carefully chosen one, one sufficiently massive that its event horizon lies quite far from its center. This is so you’ll have plenty of time between crossing the event horizon and approaching the region of insane gravitational gradient near the center to make your observations and escape again.

As you fall toward the black hole, you notice some things which strike you as highly unusual, but because you know your general relativity they do not shock or frighten you. First, the stars behind you — that is, in the direction that points away from the black hole — grow much brighter. The light from those stars, falling in toward the black hole, is being blue-shifted by the gravitation; light that was formerly too dim to see, in the deep infrared, is boosted to the point of visibility.

Simultaneously, the black patch of sky that is the event horizon seems to grow strangely. You know from basic geometry that, at this distance, the black hole should subtend about a half a degree of your view — it should, in other words, be about the same size as the full moon as seen from the surface of the Earth. Except it isn’t. In fact, it fills half your view. Half of the sky, from notional horizon to notional horizon, is pure, empty blackness. And all the other stars, nearly the whole sky full of stars, are crowded into the hemisphere that lies behind you.

As you continue to fall, the event horizon opens up beneath you, so you feel as if you’re descending into a featureless black bowl. Meanwhile, the stars become more and more crowded into a circular region of sky centered on the point immediately aft. The event horizon does not obscure the stars; you can watch a star just at the edge of the event horizon for as long as you like and you’ll never see it slip behind the black hole. Rather, the field of view through which you see the rest of the universe gets smaller and smaller, as if you’re experiencing tunnel-vision.

Finally, just before you’re about to cross the event horizon, you see the entire rest of the observable universe contract to a single, brilliant point immediately behind you. If you train your telescope on that point, you’ll see not only the light from all the stars and galaxies, but also a curious dim red glow. This is the cosmic microwave background, boosted to visibility by the intense gravitation of the black hole.

And then the point goes out. All at once, as if God turned off the switch.

You have crossed the event horizon of the black hole.

Focusing on the task at hand, knowing that you have limited time before you must fire up your magical spaceship engine and escape the black hole, you turn to your observations. Except you don’t see anything. No light is falling on any of your telescopes. The view out your windows is blacker than mere black; you are looking at non-existence. There is nothing to see, nothing to observe.

You know that somewhere ahead of you lies the singularity … or at least, whatever the universe deems fit to exist at the point where our mathematics fails. But you have no way of observing it. Your mission is a failure.

Disappointed, you decide to end your adventure. You attempt to turn your ship around, such that your magical engine is pointing toward the singularity and so you can thrust yourself away at whatever arbitrarily high velocity is necessary to escape the black hole’s hellish gravitation. But you are thwarted.

Your spaceship has sensitive instruments that are designed to detect the gradient of gravitation, so you can orient yourself. These instruments should point straight toward the singularity, allowing you to point your ship in the right direction to escape. Except the instruments are going haywire. They seem to indicate that the singularity lies all around you. In every direction, the gradient of gravitation increases. If you are to believe your instruments, you are at the point of lowest gravitation inside the event horizon, and every direction points “downhill” toward the center of the black hole. So any direction you thrust your spaceship will push you closer to the singularity and your death.

This is clearly nonsense. You cannot believe what your instruments are telling you. It must be a malfunction.

But it isn’t. It’s the absolute, literal truth. Inside the event horizon of a black hole, there is no way out. There are no directions of space that point away from the singularity. Due to the Lovecraftian curvature of spacetime within the event horizon, all the trajectories that would carry you away from the black hole now point into the past.

In fact, this is the definition of the event horizon. It’s the boundary separating points in space where there are trajectories that point away from the black hole from points in space where there are none.

Your magical infinitely-accelerating engine is of no use to you … because you cannot find a direction in which to point it. The singularity is all around you, in every direction you look.

And it is getting closer.

felixfoertsch.de

Apple Colors in SCSS

Ideas

Product Ideas

Web App Ideas

Computer and Phone App Ideas

Apps that already exist (or probably exists), but require better design, should not cost money or should be open source

Strategies from the Happiness Lab

The Collection

Web Services

Software

Pictures, Design, Illustrating

Random Apps

Install Mailtrain on Uberspace 7

Installation

Configuration

Database Setup

Mailtrain Config

Web Backend Config

Supervisord Daemon Setup

Login and Change Admin Credentials

Finishing installation

Best Practices

Collection of High Quality Swift Libraries

Helper

Use the Pumping Lemma for Regular Languages

My Explanation

1. Creating a visual model in your mind.

2. Doing a proof.

Die Rechnung

iPad Gestures

Blackhole

Blackhole