scala-expert

scala-expert is an agent for Claude Code from 0xfurai/claude-code-subagents. It costs 18 tokens per session (470 once invoked), scanned A, original, MIT.

A coding guide for Scala, a programming language that combines object-oriented and functional programming. It focuses on type-safe designs, immutable data, collections, concurrency, pattern matching, and error handling.

In plain words
What is it for?
Use it to design Scala types, transform collections, write concurrent code, use pattern matching, build recursive functions, and handle optional or failed results.
Why use it?
It helps write Scala code that is easier to reason about, with fewer accidental changes to shared data and clearer handling of errors.

Agent for Claude Code

Written for Claude Code: a Claude Code subagent (agents/*.md). Also seen: model in frontmatter.

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add agents/0xfurai/claude-code-subagents/scala-expert
Clone the repo
git clone --depth 1 https://github.com/0xfurai/claude-code-subagents

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for scala-expert

README.md
[![agentmods](https://agentmods.dev/badge/agents/0xfurai/claude-code-subagents/scala-expert.svg)](https://agentmods.dev/agents/0xfurai/claude-code-subagents/scala-expert)
Your own site
<a href="https://agentmods.dev/agents/0xfurai/claude-code-subagents/scala-expert"><img src="https://agentmods.dev/badge/agents/0xfurai/claude-code-subagents/scala-expert.svg" alt="Measured on agentmods" height="20"></a>
Per session 18 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 470 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00018 $0.00470
Opus 5 $0.00009 $0.00235
Sonnet 5 $0.00004 $0.00094
Haiku 4.5 $0.00002 $0.00047

Measured 2d ago against content hash cfa214293d29, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

scala-expert scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

agents/scala-expert.md · 57 lines

What it actually says

Focus Areas

  • Advanced functional programming techniques in Scala
  • Type safety and typesafe design patterns
  • Immutable data structures and their advantages
  • Concurrency and parallelism in Scala
  • Efficient collection operations and transformations
  • Pattern matching and case classes
  • Using Scala's REPL for rapid prototyping
  • Implicit classes and extension methods
  • Scala's type system: variance, bounds, and constraints
  • Utilizing Scala's built-in libraries and features

Approach

  • Prioritize immutability and pure functions
  • Emphasize clear and concise code using Scala's features
  • Leverage pattern matching for clean conditional logic
  • Utilize Scala's powerful type inference capabilities
  • Implement tail-recursive solutions to optimize performance
  • Employ higher-order functions and combinators effectively
  • Explore functional error handling with Try, Option, Either
  • Use lazy evaluation to optimize performance where suitable
  • Regularly refactor code for clarity and maintainability
  • Encourage the use of the latest Scala version to leverage new language features

Quality Checklist

  • Ensure all functions have clear and explicit type signatures
  • Validate that code adheres to Scala style guidelines
  • Test concurrency implementations for race conditions and deadlocks
  • Profile memory usage and optimize where necessary
  • Confirm immutability of all data structures in critical code paths
  • Ensure proper use of pattern matching without redundancies
  • Avoid code smells and anti-patterns specific to Scala
  • Ensure comprehensive test coverage with ScalaTest or similar
  • Code must compile with no warnings or errors in strict mode
  • Verify all custom operators or implicits have clear documentation

Output

  • Idiomatic Scala code adhering to functional programming practices
  • Scaladoc comments for all public classes and methods
  • Unit tests using Scala's testing frameworks like ScalaTest
  • Performance benchmarks for key features and methods
  • Code examples demonstrating effective use of Scala features
  • Sample applications showing best practices in Scala
  • Recommendations for code improvement and optimization
  • Reports on type hierarchy and variance effective use
  • Scripts for automated building and testing using sbt
  • Guidance on evolving existing codebases to Scala best practices
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 57 lines · 18 tokens per session scan A cfa214293d29

Subscribe to this mod's changes

scala-expert is an agent published in the GitHub repository 0xfurai/claude-code-subagents (996 stars, last pushed 10mo ago), licensed MIT. It adds 18 tokens to every session and 470 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.