Yuichi Sato

@yasaichi

Software Engineer at a Tokyo-based company

Tokyo, JapanJoined October 2022

About

Typescript/Effect enthusiast, Functional Programming pragmatist, Co-author of “Perfect Ruby on Rails“, ex-CTO at a public company.

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Yuichi Sato's blogs

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blog.yasaichi.com

Choose Languages for Leverage, Not Loyalty

For most of modern software history, choosing a programming language meant navigating limitations.Ecosystems, tooling quality, runtime guarantees, and team experience forced trade-offs. Language decisions were as much about constraints as they were a...

Dec 1, 20254 min read

blog.yasaichi.com

When You See Abstract Structures, Design Becomes Easier

While developing an e-commerce system, I once designed a model called DeliveryDateConstraint to represent delivery restrictions decided by sellers. At first, it looked simple enough: each product had its own shipping rule.But later I realised that cu...

Nov 8, 20253 min read

blog.yasaichi.com

Presentation (JA): TSKaigi 2025

Deck https://decks.yasaichi.com/20250524/pragmatic-functional-programming-in-typescript Abstract Functional programming concepts such as pure functions, immutability, and monads are increasingly familiar to TypeScript developers, yet many struggle ...

May 25, 20251 min read

blog.yasaichi.com

Handling Known and Unknown Unknowns with Testing and Observability

In modern software development, we often face three types of risks: Known knowns: issues we are aware of and understand. Known unknowns: issues we know exist but lack full understanding. Unknown unknowns: issues we neither know exist nor understan...

Apr 28, 20253 min read

blog.yasaichi.com

Improving Primary Key Performance: Alternatives to UUID v4

In many applications, a primary key must be unique and hard to guess. Developers often choose UUID v4 for these benefits. However, there are trade-offs in performance. Pros and Cons of Using UUID v4 as a Primary Key UUID v4 gives global uniqueness an...

Mar 16, 20252 min read

Yuichi Sato

About

Available for

Yuichi Sato's blogs

Recently published

Choose Languages for Leverage, Not Loyalty

When You See Abstract Structures, Design Becomes Easier

Presentation (JA): TSKaigi 2025

Handling Known and Unknown Unknowns with Testing and Observability

Improving Primary Key Performance: Alternatives to UUID v4

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Yuichi Sato

About

Available for

Yuichi Sato's blogs

Recently published

Choose Languages for Leverage, Not Loyalty

When You See Abstract Structures, Design Becomes Easier

Presentation (JA): TSKaigi 2025

Handling Known and Unknown Unknowns with Testing and Observability

Improving Primary Key Performance: Alternatives to UUID v4