HAPI

A zero-overhead static composition engine for C++.

Enables modular, type-safe, and high-performance system design through advanced compile-time composition.

---

#include <hapi/hapi.h>

// Building a structural compile-time Abstract Syntax Tree (AST)
using MyMenu = MenuDef<
  Title<"Main">,
  StaticBody<
    ItemDef<Id<1>,Action<op1>>,
    ItemDef<Id<2>,Action<op2>>,
    MenuDef<...>>
  >
>;

int main() {
    MyMenu::printMenu(SerialOut);
}

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Why HAPI?

Modern embedded and systems programming often faces a difficult choice:

• Low-level C offers performance and predictability, but poor structure and maintainability.
• Traditional C++ provides abstraction, but often at the cost of runtime overhead and complexity.

HAPI provides a third path: zero-overhead static composition. It lets developers build clean, composable, high-level APIs that the compiler transforms into highly efficient, deterministic code.

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Core Pillars

• Static Composition — Components are assembled at compile time into flat, cache-friendly structures with full inlining.
• Type-Level Validation — Structural and semantic rules are verified during compilation using powerful predicates.
• Zero Runtime Cost — All composition and validation happens statically. No vtables, minimal indirection, predictable memory layout.
• Functional Influence — Strong emphasis on composition, immutability of structure, and making invalid states unpresentable.

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Documentation

• Component Architecture — How components, structural blocks, and hardware abstraction layers work.
• API Reference — Core types, patterns, and advanced usage.

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Made with obsession in the Azores 🇵🇹
By Rui Azevedo • @ruihfazevedo