lib-returns

Implement FlextResult on dry-python/returns for railway-oriented error handling.

Updated May 20, 2025
One-click install
npx skills add https://github.com/flext-sh/flext --skill lib-returns
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: lib-returns
Source: https://github.com/flext-sh/flext/tree/main/.claude/skills/lib-returns
Command: npx skills add https://github.com/flext-sh/flext --skill lib-returns

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes scripts (resource) and references (resource) components.

What problem does it solve?

This Skill provides a robust and declarative way to handle operations that can either succeed with a value or fail with an error, preventing runtime exceptions and simplifying error propagation.

Core Features & Use Cases

  • Railway-Oriented Programming: Chain operations using .map() and .flat_map() for pure transformations and result-returning operations, respectively.
  • Error Recovery: Gracefully handle failures using .lash() and .recover() instead of imperative if/else checks.
  • Use Case: Safely process user input, perform database operations, or call external APIs, ensuring that errors are caught and handled predictably within a composed chain of operations.

Quick Start

Use the lib-returns skill to safely parse a JSON string into a Python dictionary, returning a failure if parsing fails.

Frequently Asked Questions about lib-returns

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I handle errors in Python without using try/except blocks?

Functional error handling in Python uses a Result type to represent success or failure explicitly. This allows you to manage failures gracefully and prevent runtime exceptions by chaining operations declaratively.

What is railway oriented programming for chaining operations?

Railway oriented programming is a pattern that chains operations using methods like map and flat_map. It routes execution through success or failure tracks, ensuring errors propagate predictably without interrupting the main flow.

How do I process a list of operations and collect all errors in Python?

You can process batch operations using collection methods like traverse and accumulate_errors. These iterate over a sequence, executing operations and aggregating any failures into a single error result.

Can I integrate a functional result type with Pydantic models?

Yes, the FlextResult type integrates directly with Pydantic models. This allows you to safely parse and validate external input, returning a structured failure if validation rules are violated.

Does the dry-python/returns library support error recovery in composed chains?

The dry-python/returns library supports graceful error recovery using the lash and recover methods. These allow you to handle failures functionally within a composed chain instead of relying on imperative if/else checks.

When should I use functional composition instead of raising exceptions?

You should use functional composition when calling external APIs or performing database operations that require predictable failure management. It prevents runtime exceptions from halting execution and simplifies error propagation across complex workflows.