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Arrow Typed Errors

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alexandru
arrow-typed-errors

Models Kotlin logical failures with Arrow's context-parameter Raise DSL and wrappers such as Either, nullable, Option, and Ior. Use when implementing or simplifying typed-error flows, translating error types, replacing verbose Either handling, validating input with accumulation, or selecting an error wrapper.

Overview

Publisheralexandru
Repositoryskills
Skill namearrow-typed-errors
Stars
51
Forks
3
Bundled files
3
Links
Skill sourceRepository
  • Markdown instructions

    A SKILL.md file the model loads on demand, so it only costs tokens when a request actually matches.

  • Works with any LLM

    AI skills are plain Markdown, not provider-specific code, so this works with GPT, Claude, Gemini, Grok, or a local model.

  • 3 bundled files

    Scripts, templates, and references the model can read while it works. Files are read-only and never executed.

  • Open source

    Published by alexandru on GitHub. Read the source before you install it.

Installation

Install the Arrow Typed Errors AI skill in TypingMind to use it with any LLM, or drop it into another agent that reads SKILL.md.

1

Install in TypingMind

TypingMind installs a skill straight from its GitHub folder — it reads SKILL.md, bundles the resource files, and stores the result locally.

  1. Open the app and go to Plugins → Skills.
  2. Choose "Install from GitHub".
  3. Paste the skill folder URL below and confirm.
    https://github.com/alexandru/skills/tree/main/skills/coding/arrow-typed-errors
  4. Enable the skill in any chat where you want it available.
Plugins → Skills → Add skill → From GitHub URL, then paste the folder URL and press Continue.
2

Install in another agent

Any agent that reads the Agent Skills format can use this skill — copy the folder into that agent's skills directory.

Claude Code — .claude/skills
git clone --depth 1 https://github.com/alexandru/skills.git /tmp/skills
mkdir -p .claude/skills
cp -r /tmp/skills/skills/coding/arrow-typed-errors .claude/skills/arrow-typed-errors
Restart Claude Code after copying so it picks up the new skill.

Use it in TypingMind

Enable Arrow Typed Errors in any TypingMind chat and the model takes it from there. Its name and description sit in the system prompt, and the moment a request matches, the model loads the full instructions itself — you never invoke it by hand, and it costs no tokens until it is actually used.

The model loads Arrow Typed Errors on its own as soon as a request matches it.

Works with any AI model

AI skills are plain Markdown instructions rather than provider-specific code, so Arrow Typed Errors is not tied to the model it was written for. Install it once in TypingMind and use it with GPT-5, Claude, Gemini, Grok, DeepSeek, Mistral, Llama, or a local model you run yourself — all on your own API keys.

  • Loaded only when it is needed

    The system prompt carries just the name and description. The instructions are fetched on the first matching request, so an idle skill costs nothing.

  • Switch models mid-chat

    Because the skill is instructions rather than code, changing model does not break it — the next model reads the same SKILL.md.

Skill instructions

This is the SKILL.md content the model loads. Read it before installing — a skill is instructions your model will follow.

Arrow Typed Errors

Quick start

  • Distinguish expected domain failures from exceptional faults before selecting an API.
  • For new code, prefer context-parameter computations (context(_: Raise<E>)) and run them into a wrapper at a boundary with either { ... }, nullable { ... }, option { ... }, or ior(...) { ... }.
  • Use Either operators for routine propagation and transformation; do not pattern match only to reconstruct Left or Right.
  • Use when when the domain genuinely branches by case or when matching a multi-state wrapper directly communicates intent.

Workflow

  1. Model domain failures as focused sealed types.
  2. Choose fail-fast composition or independent validation accumulation.
  3. Implement internal logic in a Raise<E> context and expose an appropriate wrapper at the public boundary.
  4. Bind nested typed computations and translate their errors at the layer boundary.
  5. Convert only expected, recoverable exceptions into typed failures.
  6. Inspect the result with a combinator or intentional case analysis at the consumer boundary.
  7. Type-check examples when introducing a less familiar Arrow API or upgrading Arrow/Kotlin.
  8. When changing examples, update and run the bundled scripts/verify-examples.kt check.

References

  • Load references/typed-errors.md for context-parameter API examples, imports, validation, wrapper usage, and the checked sample location.
  • Load references/best-practices.md when designing or reviewing code, especially to simplify verbose Either handling without turning when into a blanket prohibition.

Bundled files

The model reads these on demand while the skill is loaded. They are exposed as readable files and are never executed.

Frequently asked questions

What does the Arrow Typed Errors AI skill do?

Models Kotlin logical failures with Arrow's context-parameter Raise DSL and wrappers such as Either, nullable, Option, and Ior. Use when implementing or simplifying typed-error flows, translating error types, replacing verbose Either handling, validating input with accumulation, or selecting an error wrapper.

Why use Arrow Typed Errors on TypingMind?

Because you install it once and use it with any model. Arrow Typed Errors is plain Markdown rather than provider-specific code, so the same skill runs on GPT-5, Claude, Gemini, Grok, or a local model — and you can switch model mid-chat without it breaking. TypingMind runs on your own API keys, so you pay providers directly instead of a per-seat subscription, and your skills and chats stay in your own storage.

How do I install Arrow Typed Errors in TypingMind?

Open Plugins → Skills → Install from GitHub in TypingMind and paste https://github.com/alexandru/skills/tree/main/skills/coding/arrow-typed-errors. TypingMind reads its SKILL.md and bundles its files and installs it as a skill you can enable per chat.

Which AI models can use Arrow Typed Errors?

Any model you connect in TypingMind. AI skills are plain Markdown instructions rather than provider-specific code, so GPT, Claude, Gemini, Grok, and local models can all load this skill when a request matches it.

How many AI models can I use with Arrow Typed Errors?

As many as you like. As long as a model supports skills, you can use Arrow Typed Errors with it — GPT, Claude, Gemini, Grok, DeepSeek, Mistral, Llama and more — all on TypingMind with your own API keys.

Is the Arrow Typed Errors AI skill free?

It is published on GitHub by alexandru. Check the repository for licensing terms. You only pay your own AI provider for the tokens you use.

What are AI skills?

An AI skill is a reusable instruction bundle that teaches an AI model how to do one specific task. It follows the open Agent Skills format: a SKILL.md file with a name and description, plus any scripts, templates or reference files the model may need. The model reads the instructions only when your request matches the skill, so an installed skill costs nothing until it is used.

How are AI skills different from plugins or MCP servers?

A plugin or MCP server gives a model new tools to call — code that runs somewhere and returns a result. An AI skill gives the model knowledge and process instead: how to approach a task, which steps to follow, what good output looks like. Skills are plain Markdown, so they need no server, no API key and no runtime, and they work with any model.

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