Why is 'unknown' preferred over 'any'?

Using 'unknown' forces the developer to perform type checking or casting before using a value, ensuring that type safety is never bypassed silently.

Why does this skill prefer 'type' over 'interface'?

Types are preferred because they compose better with unions and intersections, support mapped types, and avoid declaration merging surprises common with interfaces.

What is the FCIS pattern mentioned in the guide?

Functional Core, Imperative Shell (FCIS) is a pattern where pure logic (the core) returns Result objects, while the outer layer (the shell) handles side effects and exceptions.

Does this skill help with React development?

Yes, it includes specific naming conventions for React-related types such as FooProps for components and FooState for state management.

How are errors handled in this style?

The style promotes the use of discriminated unions and Result types (like neverthrow) to make error states explicit and type-safe rather than relying on catch blocks.

TypeScript House Style Guide

Name: TypeScript House Style Guide
Author: ed3dai

byed3dai

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Developer Tools

Enforces a rigorous TypeScript coding standard focused on type safety, immutability, and functional programming patterns.

This skill provides a comprehensive set of TypeScript coding standards designed to minimize bugs and improve maintainability. It emphasizes the use of types over interfaces, strict immutability through readonly parameters, and the Functional Core, Imperative Shell (FCIS) pattern. By providing explicit guidance on naming conventions, function declarations, and error handling via discriminated unions, it ensures that Claude produces production-grade code that is consistent, predictable, and easy to refactor.

Key Features

015 GitHub stars

02Enforces 'type' declarations over interfaces for superior composition

03Implements Functional Core, Imperative Shell (FCIS) architecture patterns

04Guides explicit async/await patterns and strict Promise return typing

05Standardizes naming conventions for Options, Config, and Result types

06Promotes immutability using readonly parameters and Array<T> syntax

Use Cases

01Standardizing a TypeScript codebase during large-scale refactors

02Enforcing functional programming principles in backend API development

03Automating code reviews to ensure alignment with type-safe implementation patterns

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add ed3dai/ed3d-plugins-testing howto-code-in-typescript

For use in Claude.ai and ChatGPT

Download Skill