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nim-c-wrappers

Generate ABI-correct Nim wrappers with raw FFI and safety layers.

Updated Aug 27, 2026
Search Tags:#error handling#callbacks#nim#c ffi#wrapper design#abi safety#memory ownership
One-click install
npx skills add https://github.com/planetis-m/skills_experiment --skill nim-c-wrappers
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: nim-c-wrappers
Source: https://github.com/planetis-m/skills_experiment/tree/main/original_skills/nim-c-wrappers
Command: npx skills add https://github.com/planetis-m/skills_experiment --skill nim-c-wrappers

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

This Skill helps you turn C FFI bindings into ABI-correct, idiomatic Nim APIs without introducing subtle bugs like wrong struct layouts, incorrect calling conventions, or unsafe ownership/lifetime handling.

Core Features & Use Cases

  • Two-layer wrapper design: keep a thin raw FFI layer for ABI-faithful declarations and add an ergonomic Nim layer for safety and convenience.
  • ABI and safety guardrails: preserve field order, avoid reordering, use correct calling conventions, and prevent enum modeling and memory mistakes in the raw layer.
  • Ownership-aware wrappers: model move-only resources with destructor patterns, avoid fake ownership for non-handle APIs, and use exception-based error translation at clear boundaries.
  • Correct C type mapping: apply consistent Nim C-interoperability types (e.g., cint, csize_t, cstring) and patterns for strings, buffers, opaque handles, and callbacks.

Quick Start

Ask the AI to generate your Nim wrapper plan by mapping the required C header elements into a minimal raw layer and a separate ergonomic layer that enforces ownership and error handling rules for your specific library.

Frequently Asked Questions about nim-c-wrappers

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

FAQPage Schema
How do I wrap a C library in Nim without causing struct layout or ABI issues?▼

Wrapping a C library in Nim safely requires separating raw FFI declarations from an ergonomic Nim layer. This approach enforces ABI-correct struct layouts, proper calling conventions, and consistent C type mapping to prevent subtle memory and layout bugs.

What is the best way to handle C memory ownership and resource lifetimes in Nim wrappers?▼

Handling C memory ownership in Nim wrappers requires modeling move-only resources with destructor patterns and avoiding fake ownership for non-handle APIs. This explicit ownership modeling ensures safe resource lifetimes across the FFI boundary.

How do I translate C error codes into Nim exceptions across an FFI boundary?▼

Translating C error codes into Nim exceptions involves establishing a well-defined boundary in your ergonomic wrapper layer. At this boundary, raw C return codes are intercepted and converted into idiomatic Nim exceptions for safe error handling.

How do I map C callbacks and calling conventions correctly when using Nim FFI?▼

Mapping C callbacks in Nim FFI requires applying the correct calling conventions and precise C type mapping in a raw declaration layer. Keeping these ABI-faithful declarations separate prevents callback modeling and memory mistakes.

When should I use a two-layer design for Nim C wrappers?▼

You should use a two-layer design for Nim C wrappers when wrapping structs, functions, callbacks, and error codes. It keeps a thin raw FFI layer for ABI-faithful declarations while adding a separate ergonomic layer for safety and convenience.

Why does my Nim C wrapper crash with invalid memory access during callback execution?▼

Nim C wrappers crash during callback execution when calling conventions are incorrect or struct field orders are reordered. Applying correct calling conventions and preserving field order in the raw FFI layer prevents these ABI safety violations.

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