Log without leitmotif

Monads are Omnipresent in Rust

Monads, as they occur in functional programming, seem crazy and difficult to understand to me. Above all explanations and references to the mathematical subfield of category theory are confusing to me. In this post, I’m trying to explain a concept that I haven’t penetrated very deeply myself, in an introductory, application-oriented and superficial way, so that you can become the head nerd at the next party of imperative nerds. This is a translation of the original German article in a collaboration between man and machine....

December 15, 2023

Simulating Worst-Case Scenarios for Passive Capital Income

After a period of deprivation and frugality, Luise has entered a phase of greater financial freedom. All her funds are in an ETF portfolio that averages a 7% return in the long term. Unfortunately, the 7% return is not constant and fluctuates significantly. Luise plans to withdraw a certain amount every month, either through dividends or by selling shares. Before I continue with a financial-themed story, I want to clarify that I’m not a financial expert....

September 25, 2023

Back-of-the-envelope Simulation of Stock Prices

When calculating financial goals, it’s often assumed, like on the informative website Finanzfluss, that there’s a fixed annual return. In the suggested return range of around 5% to 7% per year, I dare to challenge the expectation of consistent returns without the fluctuations of stock investments. Therefore, I’ve briefly explored simulating stock prices and implemented a savings plan calculator based on this concept. The focus of this article is on the simulation aspect....

August 16, 2023

Geographic Re-Balancing of Stock ETFs

Various channels claim that rebalancing your stock portfolio increases your return on investment. In this article, I will present the analysis of historical data on geographic allocations of the popular indices MSCI World and MSCI Emerging Markets. 2 remarks before we start: This article was translated from German to English in collaboration between man and machine *To be honest, I was a little disappointed by the translation performance of translate.google.com. Even though I am talking finance in this article, I’m not a finance expert at all....

February 18, 2023

New Blog with Hugo

My old wordpress blog has quit the service. Without consultation. Suddenly I could no longer log into the administration area under ninety.de. The first best debugging tips from the net turned out to be a waste of time. I denounced this while kicking Wordpress into the garbage can instead of asking ChatGpt*the cocky chat bot of the not-so-new startup OpenAI, which is a topic for another time for help. The greed for more simplicity and security was awakened....

January 9, 2023

Parsing Operators in Rust

The Advent of Code is just around the corner. This is an advent calendar of programming tasks, the solution of which can serve as a pastime for the fun of joy. After successfully processing a task, you receive a virtual golden star. My first participation was in 2020. At the time, I thought I’d try to do this directly in the Rust programming language, which I hadn’t used before. By the way, this article is not only intended to shed light on an interesting Advent of Code task, but also to highlight the flexibility of my Rust library Exmex, which is discussed below as part of the solution....

November 11, 2021

Sequences of partial reductions in Elm

In my previous article I derived the calculation for passive income from invested assets and demonstrated a small calculator. It struck me that there was a slight delay in the case of high annual numbers. The cause of the delay lies in my implementation of the formula $$ \sum_{k = 1}^{m-1} \frac {1} {\prod_ {t = 1} ^ {k} w_t}. $$ As described in more detail in the article mentioned above, $ w_t $ denotes the relative market value in the month $ t $ and $ m $ the total number of months....

June 1, 2021

Passive income from stock market investments

How can you generate passive income from return on stock market investments or dividends*Dividends are of course also a kind of investment income. I just wanted to mention them again because they play a special role in this article. and when does that make sense? In addition to explanations and anecdotes, I also present mathematical formulas to answer this question🥳*That's a smiley celebrating the existence of math in this article.....

May 13, 2021

First steps towards dynamic web apps in Elm

Some time ago I was able to listen to the episode We’re Teaching Functional Programming Wrong of the podcast Corecursive. Richard Feldman tells of a purely functional language with which you can actually create dynamic web pages. It is not even necessary to understand what a Monad is. Since I consider object-oriented programming to be overrated*The talk [Free your Functions](https://www.youtube.com/watch?v=WLDT1lDOsb4) by Klaus Iglberger highlights some practical aspects my point of view....

April 19, 2021


I’m just bringing my public diary back to life. I write in German and cooperate with machines to translate articles to English.

April 10, 2021