ClaudSkills / Engineering / code-quality

2020-hindsight-scala

Q: What is a Claude Code skill and how does the 2020-hindsight-scala skill fit in?

A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. 2020-hindsight-scala is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Engineering category. Learn more at https://claudskills.com/learn/what-is-skill-md/.

Category: Engineering · Sub-category: code-quality · Last updated: 2026-08-10

type:review

Refactor Scala code and apply good practices from 2020 Hindsight Scala (https://2020-hindsight-scala.kevinly.dev/docs/). Use this skill whenever writing new Scala code, reviewing Scala code, or refactoring existing Scala code. Also trigger when the user mentions Scala best practices, ADTs, type safety, Option/Either usage, or asks to clean up / improve Scala code quality. This skill applies even if the user doesn't explicitly mention "2020 hindsight" — any Scala code writing or refactoring should follow these practices.

Security AStatic scan found no risk patternsHow grading works ›

From the source SKILL.md

Apply these practices when writing new Scala code or refactoring existing Scala code. Reference: https://2020-hindsight-scala.kevinly.dev/docs/

What this skill does

2020-hindsight-scala is a community-contributed Claude Code skill in the code-quality sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/hindsight-scala/ and loads when your prompt matches the skill's trigger.

Who uses this skill

The 2020-hindsight-scala Claude Code skill is built for software engineers, backend developers, full-stack teams, and technical leads building and maintaining production systems. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 179,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).

How to install

Free

Manual install (2 steps)

mkdir -p ~/.claude/skills/hindsight-scala
curl -L https://claudskills.com/skills/hindsight-scala/SKILL.md \
  -o ~/.claude/skills/hindsight-scala/SKILL.md

Or just download SKILL.md directly and drop it into ~/.claude/skills/hindsight-scala/. Claude Code auto-discovers it on next session.

Skills live at ~/.claude/skills/hindsight-scala/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\hindsight-scala\SKILL.md on Windows. See the full install guide for step-by-step instructions.

📱 Install from your phone or desktop Telegram

Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →

Pro

One-click install via the desktop app

The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.

Pro

For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.

See pricing → Download desktop app

Frequently asked questions

How do I install the 2020-hindsight-scala Claude Code skill?

Install via the ClaudSkills desktop app (one click) or copy SKILL.md from the source repository to ~/.claude/skills/hindsight-scala/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.

What does the 2020-hindsight-scala skill do?

Is this skill free to install?

Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.

When should I use the 2020-hindsight-scala skill?

Use 2020-hindsight-scala when your Claude Code task falls under the Engineering category — specifically in the code quality area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use 2020-hindsight-scala" or describe the task and let Claude pick). Browse related skills at /category/engineering/.

What is a Claude Code skill and how does the 2020-hindsight-scala skill fit in?

A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. 2020-hindsight-scala is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Engineering category. Learn more at /learn/what-is-a-claude-skill/.

Attribution & license

Source: https://github.com/kevin-lee/ai-dumping-ground/blob/HEAD/skills/2020-hindsight-scala/SKILL.md
License: MIT
Author: kevin-lee

Cite this skill

If you reference this skill in a blog post, paper, or documentation, you can cite it as:

APA

kevin-lee. (2026). 2020-hindsight-scala [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/hindsight-scala/

BibTeX

@misc{hindsight-scala-2026,
  author    = {kevin-lee},
  title     = {2020-hindsight-scala [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/hindsight-scala/}
}

Embed this skill

Promote, attribute, or link this skill from your own README, blog post, or documentation. All three snippets are free to use — no sign-up, no API key. More distribution surfaces →

Badge

[![ClaudSkills](https://claudskills.com/badge/hindsight-scala.svg)](https://claudskills.com/skills/hindsight-scala/?utm_source=badge&utm_medium=readme&utm_campaign=skill_badge)

Security scan

Grade A · scanned 2026-08-10 — free static scan against the OWASP Agentic Skills Top 10.

No risk patterns were found in any of the ten OWASP-aligned categories. How grading works ›

✓ Prompt injection
✓ Data exfiltration
✓ Supply chain
✓ Reverse shell
✓ Credentials
✓ Execution
✓ Filesystem
✓ Persistence
✓ Obfuscation
✓ Network

Show this grade on your repo (click to copy):

[![Security: A](https://img.shields.io/badge/Security-A-2e7d32)](https://claudskills.com/skills/hindsight-scala/#security)

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