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Mastodon @matejcerny@witter.cz

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Followers

Account age

3 yrs

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Known for

$There is a new Scala 3 optics library worth checking out: cats-eo. It unifies optic families under a single trait, features macro derivation backed by Hearth and delivers massive performance gains (such as traversals running up to 11x faster with a fraction of the memory overhead compared to Monocle).$ 1 views There is a new Scala 3 optics library worth checking out: cats-eo. It unifies optic families under a single trait, features macro derivation backed by Hearth and delivers massive performance gains (such as traversals running up to 11x faster with a fraction of the memory overhead compared to Monocle).

You know what that means, right? Some library is getting a massive performance boost! This time it's Scala Yaml, which is up to 10x faster with ~20x lower memory allocation per operation! 🤯
If you're curious, take a look through the PR - there are plenty of cool techniques to learn!
https://github.com/VirtusLab/scala-yaml/releases/tag/v0.3.3

1 views You know what that means, right? Some library is getting a massive performance boost! This time it's Scala Yaml, which is up to 10x faster with ~20x lower memory allocation per operation! 🤯 If you're curious, take a look through the PR - there are plenty of cool techniques to learn! https://github.com/VirtusLab/scala-yaml/releases/tag/v0.3.3

📊 Post engagement

📊 Activity & format

Posting cadence

5 / week

Posts several times a week.

Content mix

Mostly text

Recent: 9 text · 3 image · 0 video.

Follower / following

1.8×

Follows 54 back. A more reciprocal / networked account.

Recent posts

View on Mastodon ↗

🔥 Top post Hey, #Java developers! Your domain models are leaking bugs and you need to fix them immediately! Start using records + sealed hierarchies. They give you: 💥 Zero illegal states 📖 Self-documenting business logic ✅ Exhaustive switch checks 📉 Fewer tests to write 🧹 Drastically less … ★ 3

https://eo.constructive.dev/ ★ 2

There is a new Scala 3 optics library worth checking out: cats-eo. It unifies optic families under a single trait, features macro derivation backed by Hearth and delivers massive performance gains (such as traversals running up to 11x fast… ★ 1 ⚠️ There is a proposal to change the default Seq implementation from List to Vector. It makes sense, but I personally would rather keep the status quo to avoid unexpected runtime changes while people are still migrating from #Scala 2 to 3.… ★ 2

What a beautiful way to start a Friday 🤣 Two signs your domain model is incomplete: ❌ You need an 'if' statement ❌ You are adding another optional argument to a function Model your actual domain states with ADTs. Stop patching logic. ★ 1 I started using Herdr about two weeks ago, and I can confirm it's really good! But to be fair, I didn't use tmux - I migrated from a plain Ghostty terminal. The main feature is the built-in agent panel - it keeps track on running AI tasks … Metals v1.6.8 out 🎉 A bit of a curious release - lots of fixes for Java, Bloop and old school editor workflows. Still, a massive effort with 119 merged PRs! https://scalameta.org/metals/blog/2026/07/23/osmium/ ★ 1

You know what that means, right? Some library is getting a massive performance boost! This time it's Scala Yaml, which is up to 10x faster with ~20x lower memory allocation per operation! 🤯 If you're curious, take a look through the PR - t… ★ 1 Is it a case of AI psychosis if I use Claude, Codex, Gemini, and Grok every day? 🤔 Could anyone tell me what is wrong with this description? It's concise, includes settings and a complete repro. Also, saying that it violates policy when you have no policy regarding LLMs is pretty ironic. Anyway, my humble pgmq wrapper is… In case you missed it, Scarf, the analytics platform which you might know from the Sonatype integration, is moving away from #Haskell. 😢 It makes me so grateful that #Scala chose a completely different, pragmatic path. With AI-ready toolin… ★ 2

🐘 Community & instance

Home server

witter.cz

Their home server on the fediverse — the instance a creator picks signals the community they belong to.

✅ Link-verified

Verified link

Proved ownership of a website linked on their profile — Mastodon's green-check verification, a real identity signal rather than a paid badge.

On Mastodon since

Nov 2022

Joined in the Twitter-exodus wave of late 2022 — part of the migration that made Mastodon a real destination.

💡 Facts

🗓️Joined Mastodon in 2022 — 3 years ago.

👁️Averages 2 views per post.

📤Posts about 5× per week.

🕵️ Fake follower check

Estimated

75/100

Good Credibility score

92%

Real Real audience

Low Fake-follower risk

High Data confidence

Est. 92% real, active audience · Low fake-follower risk.
Engagement (~2.1% of followers engage each post) is around typical for Mastodon.
Verified account.
Established account (3+ years old).

Heuristic estimate from engagement, follower ratios, account age & growth — a screening signal, not a guarantee.

💚 Brand affinity

Estimated

Brands Matej Cerny's audience is most likely to respond to — from detected sponsorships in this niche.

Keeps

About

Scala & Functional Programming Engineer. Database/SQL Veteran.

📸 Gallery

🔀 Audience overlap

Estimated

Estimated shared audience with similar creators — useful for avoiding overlap (or doubling down) when planning a campaign.

KalenXI 🏳️‍🌈 52%

Clyde (GameTank Guy) 18%

Child of darkness 17%

Johannes 16%

thegreekgeek 16%

Městský Vlk 15%

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Mastodon ＋

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@mestskyvlk@cztwitter.cz

96 Followers

Mastodon ＋

Johannes ✓

@swars@infosec.exchange

97 Followers

Mastodon ＋

Child of darkness

@mcchaos@metalhead.club

97 Followers

Mastodon ＋

thegreekgeek ✓

@thegreekgeek@mstdn.io

97 Followers

Mastodon ＋

Clyde (GameTank Guy)

@clyde@mastodon.gamedev.place

97 Followers

🏆 Awards & milestones

Next: 🟣 10K Followers — 9.9K followers to go

🛡️ Brand safety

✅Brand-safe90/100

✓ Verified / Partner account
✓ Established channel (3+ yrs)

A heuristic signal for brands from public data & recent titles — not a moderation verdict.

Details

PlatformMastodon

JoinedNov 2022 · 3 yrs

Followers97

Updated21 hours ago

🤝 Brands they've worked with

✓ From their content

Sponsors Matej Cerny has actually partnered with — detected in their videos. Proof they take on & deliver brand deals.

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How many followers does Matej Cerny have?

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📊 Post engagement

📊 Activity & format

Recent posts

🐘 Community & instance

💡 Facts

🕵️ Fake follower check

💚 Brand affinity

About

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🔀 Audience overlap

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