What programming language are XRPL Hooks written in?

XRPL Hooks are written in C/C++ and compiled to WebAssembly (WASM), though theoretically any language that compiles to WASM could work.

Primary Language: C

Why C: 1. Direct WASM compilation: Excellent WASM toolchain support 2. Low-level control: Optimize for 64 KB size limit 3. Deterministic behavior: No runtime surprises 4. Performance: Compiled code runs efficiently 5. Embedded systems heritage: Similar constraints to embedded development

Toolchain: - Compiler: Clang/LLVM with WASM target - Optimizer: wasm-opt for size/speed optimization - Debugger: WASM debugging tools

Alternative Languages (Theoretical):

Rust: - ✅ Compiles to WASM - ✅ Memory safety guarantees - ✅ Growing WASM support - ⚠️ Larger binary sizes (harder to stay under 64 KB) - ⚠️ Less mature WASM tooling than C - Status: Possible but challenging

AssemblyScript (TypeScript-like): - ✅ Designed specifically for WASM - ✅ JavaScript-familiar syntax - ⚠️ Less control over binary size - ⚠️ Limited low-level optimization - Status: Possible for simple Hooks

Go (Golang): - ⚠️ Large runtime requirements - ⚠️ Difficult to fit in 64 KB - ⚠️ Non-deterministic garbage collection - Status: Not practical

Solidity: - ❌ Compiles to EVM bytecode, not WASM - ❌ Cannot be used directly - Future: Might work via transpilers

Practical Reality: C Dominates

Developer Experience:

1. C Development Environment: ```bash # Install WASM toolchain apt-get install clang lld

# Clone Hooks examples git clone https://github.com/XRPL-Labs/xrpl-hooks

# Build Hook clang --target=wasm32 -O3 hook.c -o hook.wasm

# Optimize for size wasm-opt -Oz hook.wasm -o hook-final.wasm ```

2. Hook Structure (C): ```c #include "hookapi.h"

int64_t hook(uint32_t reserved) { // Your Hook logic here // Access transaction data uint8_t hash[32]; otxn_id(hash, 32, 0); // Read state uint8_t state[32]; state_get(state, 32, "counter", 7); // Your business logic // ... // Accept transaction accept(0, 0); return 0; } ```

3. Hook API Functions:

Hooks have access to ~70 API functions: - Transaction data access (otxn_*) - State management (state_*) - Ledger queries (ledger_*) - Utility functions (util_*) - Control flow (accept, rollback)

Learning Curve:

For Developers With:

C/C++ Background: - Easy transition - Familiar with pointers and memory management - Learning curve: 1-2 weeks to proficiency

JavaScript/Python Background: - Steeper learning curve - Must learn C basics - Must understand WASM compilation - Learning curve: 4-8 weeks

Solidity/Smart Contract Background: - Concepts transfer (state, transactions, etc.) - Syntax very different - Must learn C paradigms - Learning curve: 3-6 weeks

No Programming Background: - Start with C programming fundamentals - Then learn Hooks-specific APIs - Learning curve: 3-6 months

Why Not High-Level Languages?

The 64 KB Size Constraint:

High-level languages bring baggage: - Runtime: Go, Java, etc. include runtime in binary - Standard library: Large footprint - Abstractions: Add bloat

C allows: - Minimal runtime (almost none) - Include only what you use - Direct control over every byte - Fit complex logic in 64 KB

Community & Resources:

Learning Resources: - XRPL Hooks Documentation: https://hooks.xrpl.org - Example Hooks repository: GitHub XRPL-Labs - Developer Discord: Active community - Tutorials and guides: Growing ecosystem

Development Tools: - Hooks Builder: Web-based IDE - Hooks Testnet: Safe testing environment - Template Hooks: Starter code examples - Debug Tools: Transaction inspection

Future Language Support:

Community efforts to enable: - Rust support: Better tooling development - Domain-specific languages: Hooks-optimized syntax - Transpilers: Convert Solidity → Hooks-compatible code

The Vision:

Eventually, developers might write Hooks in higher-level languages that compile efficiently to WASM, similar to how: - Solidity → EVM bytecode - Move → Move bytecode - Future DSL → Hooks WASM

But for now and near future: C is the way.

Comparison to Competitors:

| Platform | Language | Difficulty | Tooling Maturity | |----------|----------|------------|------------------| | Ethereum | Solidity | Medium | Excellent | | Cardano | Plutus (Haskell) | Hard | Good | | Solana | Rust | Hard | Good | | XRPL Hooks | C | Medium-Hard | Developing |

The Trade-off:

XRPL chose efficiency and determinism (C/WASM) over developer convenience (high-level DSL). This reflects XRPL's core philosophy: performance and reliability first.

*Last updated: February 2026*