DEV Community: Rainer M.

🦀 Rust’s Real Win: It Didn’t Make Our App Faster, It Made Us Less Terrified

Rainer M. — Wed, 22 Jul 2026 10:07:47 +0000

Let’s be honest. When we talk about migrating a service to Rust, we all envision the same thing: liquid-lightning latency, CPU graphs dropping off a cliff, and a single server suddenly handling the traffic of a small European nation.
Momento spent over three years rewriting its services from Kotlin to Rust. They expected raw speed. What they actually got was a massive upgrade to their engineering sanity.
Here is what actually happens when you ditch the JVM for the crab emoji.

1. The Compiler is Your Aggressive Pair Programmer

In Kotlin, you swap an account_id and a user_id because they are both strings. Your IDE doesn't care. Your reviewer misses it. Production explodes at 2 AM.
In Rust, the compiler treats you like a suspect in a crime scene. By forcing engineers to declare custom types and explicitly deal with references, entire categories of bugs are vaporized before they even touch a Pull Request.

[ Your Brain ] -> "I'll just share this variable real quick..."
[ The Borrow Checker ] -> "Over my dead body."

Yes, the learning curve looks like a vertical wall. But fighting the compiler on your laptop is infinitely better than fighting a memory leak in production.

2. Plot Twist: Rust Doesn't Automatically Fix Bad Code

If you write a bad algorithm in Python, it’s slow. If you write a bad algorithm in Rust, it is safely, concurrently, and beautifully slow.
Momento’s first Rust rewrite didn't magically reduce latency. Why? Because the code was still doing silly things, like repeatedly allocating dynamic string memory for metrics inside the main request path.
They still had to bust out flamegraphs and Criterion to fix poor lock designs and profile hot paths. Rust stops you from shooting yourself in the foot, but it won't write your code for you.

3. The Real Flex: Throughput & The Cloud Bill

While latency didn't drop instantly, instance throughput absolutely skyrocketed.
Momento went from handling 20,000 requests per second to 100,000 on a single instance.

Traditional scaling: "Throw more AWS instances at it!"
Rust scaling: "We deleted 80% of our servers and the app is fine."

When you are an infrastructure company, that kind of resource efficiency makes finance executives weep tears of joy. In fact, they later picked Rust for a workflow service that wasn't even performance-sensitive, just because they loved the explicit code and consistency.

4. How to Adopt Rust (Without Firing Your Team)

Momento didn’t rewrite their entire core infrastructure on day one. They started small:

They built a tiny internal CLI tool.
They migrated one performance-critical hot spot.
They leaned heavily on one "Rust Guru" who already understood lifetimes and async patterns to prevent the rest of the team from crying over compiler errors.

The Takeaway

Rust isn't a magical performance engine that fixes lazy engineering. It is an engineering safety net. It gives your team the confidence to experiment, refactor, and push changes without the constant lingering dread that everything is about to break.

WWDC 2026 is June 8–12 : And Apple's Finally Talking About AI

Rainer M. — Tue, 24 Mar 2026 09:40:27 +0000

Apple just confirmed WWDC 2026 runs June 8 to 12, both online and in-person at Cupertino. Mark the calendar - this one's shaping up to be more relevant to developers than last year's.
If you watched last year's keynote, you remember the Liquid Glass design overhaul dominated everything. AI was barely mentioned. This year Apple is explicitly teasing "AI advancements" in their announcement copy, which suggests the keynote is going in a very different direction.

What developers should actually watch for

The Siri situation has been dragging for a while. A more capable Siri with real personal context and on-screen awareness has been reportedly delayed more than once. WWDC 2026 might be where that finally ships - especially after Apple signed a deal with Google to bring Gemini into the mix for AI features across its platforms.

On the developer tooling side, things have been moving fast already. Earlier this year, Xcode added support for Claude and OpenAI's Codex as agentic coding tools. That's a significant step - moving from simple autocomplete into agents that can plan and execute multi-step tasks inside your IDE. It'll be interesting to see if Apple formalizes any of that into first-party tooling at the conference.

The other thing to keep an eye on is the Foundation Models framework - introduced last year to let developers run AI models fully on-device, offline. If Apple extends that with new capabilities or better APIs this cycle, it opens up a lot for privacy-focused apps that can't rely on cloud inference.

Where to watch
Everything streams live on the Apple Developer app, the developer website, and the Apple Developer YouTube channel. If you're in China, Bilibili is the place.

Personally, the Xcode agent direction is what I'm most curious about. Cursor and Antigravity have been eating Apple's lunch on developer experience for the past year. It'd be good to see them actually compete.
What are you hoping to see at WWDC this year? Drop it in the comments.

Start New Journey for learning Rust

Rainer M. — Wed, 07 Jan 2026 05:28:54 +0000

Hello everyone.
I'm excited to share my experience starting to learn Rust, which I'll be doing using rustlings and the official Rust documentation.
I'm familiar with C++ and C#. To improve my skills in the Web3 era, I decided to learn Rust and participate in Web3 projects.
My first goal is to master the basics of Rust within a week.