Fp Errors

Practical Error Handling with fp-ts

This skill teaches you how to handle errors without try/catch spaghetti. No academic jargon - just practical patterns for real problems.

The core idea: Errors are just data. Instead of throwing them into the void and hoping someone catches them, return them as values that TypeScript can track.

When to Use

• You need to replace exception-heavy code with Either or TaskEither.
• The task involves validation, domain errors, or clearer error contracts in TypeScript.
• You want pragmatic fp-ts error-handling guidance for real application code.

Core Workflow

1. Confirm the request matches this skill's trigger, scope, and risk profile.
2. Use the topic map to identify the relevant pattern, checklist, or example before writing detailed guidance or code.
3. Load references/full-guidance.md when implementation details, examples, anti-patterns, validation checks, or edge cases are needed.
4. Apply only the relevant guidance instead of loading or repeating the entire reference by default.
5. Verify the result against any validation checks, limitations, security notes, or platform constraints in the reference.

Topic Map

• Stop Throwing Everywhere
• The Problem with Exceptions
• The Solution: Return Errors as Values
• The Result Pattern (Either)
• Converting Throwing Code to Either
• Common Either Operations
• Chaining Operations That Might Fail
• Before: Nested Try/Catch Hell
• After: Clean Chain with Either
• Different Error Types? Use chainW
• Collecting Multiple Errors
• Before: Collecting Errors Manually
• After: Validation with Error Accumulation
• Field-Level Errors for Forms
• Async Operations (TaskEither)
• Before: Promise Chain with Error Handling
• After: Clean TaskEither Pipeline
• Retry Failed Operations

Reference Map

• references/full-guidance.md preserves the complete original guidance, including examples and detailed edge cases.

Limitations

• Use this skill only when the task clearly matches the scope described above.
• Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
• Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.

Progressive Loading

Keep this SKILL.md as the compact routing and workflow entrypoint. Load the reference file only when the user task requires the deeper implementation material.