A developer's writing space.Not merely on the surface, but a life of exploring and contemplating the essence.
I previously wrote a post called “What Is Good Code? On the Illusion of Readability” where I discussed how subjective and context-dependent the formula “good code = readable code” really is. The conclusion that people judge readability differently is fair enough. But if you trace the mechanics behind it — where that sense of “this is easy to read” actually comes from — you start to find some hints.
Jan 30, 2026
We use types every day and face countless type errors. Each time, we read the error message, search for a fix, and move on — but we rarely stop to think deeply about why the type system behaves the way it does. Knowing how to use types is like understanding grammar. Understanding the type system is closer to understanding why that grammar was designed the way it is.
Jan 25, 2026
In this post, I want to talk about what I’ve been thinking about over the roughly two and a half years I’ve spent as a frontend chapter lead at Toss. My job and goal as a chapter lead at Toss is clear: make the Toss frontend chapter the most excellent engineering organization in the world.
Jan 24, 2026
In this post, continuing from my previous one, I want to dig deeper into how declarative programming manifests in real-world code. Just explaining theory would be boring, so let’s explore declarative programming in more detail through overlay-kit, a library that makes it easy to manage overlay elem…
Oct 07, 2025
When conducting technical interviews, I often ask candidates about the reasoning behind their decisions in take-home assignments. A common answer I hear is “because this approach is more declarative.” But when I follow up with “What makes it declarative?” or “What does declarative code actually mean?”, clear answers are surprisingly rare. So in this post, I want to share my thoughts on what it truly means for code to be declarative.
Sep 07, 2025
Throughout life, we face countless problems. Just looking at the practical ones — education, careers, job changes, finances, growth — we encounter all kinds of missions. And when I talk to people about these things, I often hear them speak as if there’s a predetermined right answer, or at least wishing there were one.
Dec 23, 2024
AI is transforming our lives in profound ways. When you use the ChatGPT mobile app and have voice conversations back and forth, it’s hard not to feel like Jarvis from Iron Man has become reality. Generative AI like ChatGPT is used for everything from casual conversation to complex problem-solving, …
Jun 23, 2024
Humans are said to be social animals who live within relationships. This is especially pronounced in East Asian cultures, where people tend to define themselves through their relationships with others — and commonly make the mistake of letting others’ perceptions and evaluations determine their sel…
Nov 21, 2023
In this post, I want to briefly share what I’ve been thinking about over the past three years — not as an IC (Individual Contributor), but as a leader — about what makes a good leader and what competencies that requires. No matter how good someone was as an IC, that experience doesn’t automatically…
Oct 30, 2023
In this post, I want to talk about abstraction. Abstraction occupies a critically important place not just in application design but across all of computer science. Yet the concept of abstraction is itself so abstract that many developers who are just starting out find themselves deeply confused by…
Jan 15, 2023
Lately, I’ve been doing more mentoring — reviewing résumés, conducting mock interviews, and discussing growth strategies with developers who are relatively new to the profession. These conversations have been happening more and more frequently. As these experiences accumulated, I started noticing p…
Sep 10, 2021
Recently, our team at Lubycon started a small project called lubycon-ui-kit together with mentees from a mentoring program. It’s still in its early stages with not much to show, but the goal is to build a UI library based on Korean typography that’s easy for domestic designers and developers to use.
Nov 28, 2020
In this post, I’m going to talk about the CORS(Cross-Origin Resource Sharing) policy which every web developer would have heard of at least once. In fact, in web development, it is not an exaggeration to say that errors occur with CORS policy violations are very common, and every web developer will…
Oct 06, 2020
During the last golden week, I migrated my blog that I had previously made using Hexo to Gatsby. In this post, I would like to share what I learned from this migration work and issues I didn’t expect. The Beginning of Yak Shaving In fact, I tried to continue using Hexo at first. Of course, it’s tru…
May 15, 2020
Writing code in functional programming means expressing the various tasks a program needs to perform as functions, then skillfully composing those functions to build a large program. Function composition is the very foundation of this paradigm, which makes it enormously important. The problem is th…
Jan 27, 2020
