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Overview

Zen C is a modern systems programming language that compiles to human-readable GNU C/C11. It provides a rich feature set including type inference, pattern matching, generics, traits, async/await, and manual memory management with RAII capabilities, all while maintaining 100% C ABI compatibility.

Community

Join the discussion, share demos, ask questions, or report bugs in the official Zen C Discord server!

• Discord: Join here
• RFCs: Propose features

Ecosystem

The Zen C project consists of several repositories. Below you can find the primary ones:

Repository	Description	Status
zenc	The core Zen C compiler (zc), CLI, and Standard Library.	Active Development
docs	The official documentation and language specification.	Active
rfcs	The Request for Comments (RFC) repository. Shape the future of the language.	Active
vscode-zenc	Official VS Code extension (Syntax Highlighting, Snippets).	Alpha
www	Source code for zenc-lang.org.	Active
awesome-zenc	A curated list of awesome Zen C examples	Growing
zenc.vim	Official Vim/Neovim plugin (Syntax, Indentation).	Active

Showcase

Check out these projects built with Zen C:

• ZC-pong-3ds: A Pong clone for the Nintendo 3DS.
• zen-c-parin: A basic example using Zen C with Parin.
• almond: A minimal web browser written in Zen C.

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Index

General	Language Reference
Overview Community RFCs Quick Start Ecosystem Documentation Standard Library Tooling LSP Debugging Compiler Support & Compatibility Contributing Attributions	Browse the Language Reference

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Quick Start

Installation

git clone https://github.com/zenc-lang/zenc.git
cd Zen-C
make clean # remove old build files
make
sudo make install

Windows

Zen C has full native support for Windows (x86_64). You can build using the provided batch script with GCC (MinGW):

build.bat

This will build the compiler (zc.exe). Networking, Filesystem, and Process operations are fully supported via the Platform Abstraction Layer (PAL).

Alternatively, you can use make if you have a Unix-like environment (MSYS2, Cygwin, git-bash).

Portable Build (APE)

Zen C can be compiled as an Actually Portable Executable (APE) using Cosmopolitan Libc. This produces a single binary (.com) that runs natively on Linux, macOS, Windows, FreeBSD, OpenBSD, and NetBSD on both x86_64 and aarch64 architectures.

Prerequisites:

• cosmocc toolchain (must be in your PATH)

Build & Install:

make ape
sudo env "PATH=$PATH" make install-ape

Artifacts:

• out/bin/zc.com: The portable Zen-C compiler. Includes the standard library embedded within the executable.
• out/bin/zc-boot.com: A self-contained bootstrap installer for setting up new Zen-C projects.

Usage:

# Run on any supported OS
./out/bin/zc.com build hello.zc -o hello

Usage

# Compile and run
zc run hello.zc

# Build executable
zc build hello.zc -o hello

# Interactive Shell
zc repl

# Show Zen Facts
zc build hello.zc --zen

Environment Variables

You can set ZC_ROOT to specify the location of the Standard Library (standard imports like import "std/vec.zc"). This allows you to run zc from any directory.

export ZC_ROOT=/path/to/Zen-C

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Language Reference

See the official Language Reference for more details.

Standard Library

Zen C includes a standard library (std) covering essential functionality.

Browse the Standard Library Documentation

Key Modules

Click to see all Standard Library modules

Module	Description	Docs
std/bigfloat.zc	Arbitrary-precision floating-point arithmetic.	Docs
std/bigint.zc	Arbitrary-precision integer BigInt.	Docs
std/bits.zc	Low-level bitwise operations (rotl, rotr).	Docs
std/complex.zc	Complex Number Arithmetic Complex.	Docs
std/vec.zc	Growable dynamic array Vec<T>.	Docs
std/string.zc	Heap-allocated String type with UTF-8 support.	Docs
std/queue.zc	FIFO queue (Ring Buffer).	Docs
std/map.zc	Generic Hash Map Map<V>.	Docs
std/fs.zc	File system operations.	Docs
std/io.zc	Standard Input/Output (print/println).	Docs
std/option.zc	Optional values (Some/None).	Docs
std/result.zc	Error handling (Ok/Err).	Docs
std/path.zc	Cross-platform path manipulation.	Docs
std/env.zc	Process environment variables.	Docs
std/net/	TCP, UDP, HTTP, DNS, URL.	Docs
std/thread.zc	Threads and Synchronization.	Docs
std/time.zc	Time measurement and sleep.	Docs
std/json.zc	JSON parsing and serialization.	Docs
std/stack.zc	LIFO Stack Stack<T>.	Docs
std/set.zc	Generic Hash Set Set<T>.	Docs
std/process.zc	Process execution and management.	Docs
std/regex.zc	Regular Expressions (TRE based).	Docs
std/simd.zc	Native SIMD vector types.	Docs

18. Unit Testing Framework

Zen C features a built-in testing framework that allows you to write unit tests directly in your source files using the test keyword.

Syntax

A test block contains a descriptive name and a body of code to execute. Tests do not require a main function to run.

test "unittest1" {
    "This is an unittest";

    let a = 3;
    assert(a > 0, "a should be a positive integer");

    "unittest1 passed.";
}

Running Tests

To run all tests in a file, use the run command. The compiler will automatically detect and execute all top-level test blocks.

zc run my_file.zc

Assertions

Use the built-in assert(condition, message) function to verify expectations. If the condition is false, the test will fail and print the provided message.

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Tooling

Zen C provides a built-in Language Server and REPL to enhance the development experience. It is also debuggable with LLDB.

Language Server (LSP)

The Zen C Language Server (LSP) supports standard LSP features for editor integration, providing:

• Go to Definition
• Find References
• Hover Information
• Completion (Function/Struct names, Dot-completion for methods/fields)
• Document Symbols (Outline)
• Signature Help
• Diagnostics (Syntax/Semantic errors)

To start the language server (typically configured in your editor's LSP settings):

zc lsp

It communicates via standard I/O (JSON-RPC 2.0).

REPL

The Read-Eval-Print Loop allows you to experiment with Zen C code interactively.

zc repl

Features

• Interactive Coding: Type expressions or statements for immediate evaluation.
• Persistent History: Commands are saved to ~/.zprep_history.
• Startup Script: Auto-loads commands from ~/.zprep_init.zc.

Commands

Command	Description
:help	Show available commands.
:reset	Clear current session history (variables/functions).
:vars	Show active variables.
:funcs	Show user-defined functions.
:structs	Show user-defined structs.
:imports	Show active imports.
:history	Show session input history.
:type <expr>	Show the type of an expression.
:c <stmt>	Show the generated C code for a statement.
:time <expr>	Benchmark an expression (runs 1000 iterations).
:edit [n]	Edit command n (default: last) in $EDITOR.
:save <file>	Save the current session to a .zc file.
:load <file>	Load and execute a .zc file into the session.
:watch <expr>	Watch an expression (re-evaluated after every entry).
:unwatch <n>	Remove a watch.
:undo	Remove the last command from the session.
:delete <n>	Remove command at index n.
:clear	Clear the screen.
:quit	Exit the REPL.
! <cmd>	Run a shell command (e.g. !ls).

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Language Server Protocol (LSP)

Zen C includes a built-in Language Server for editor integration.

• Installation & Setup Guide
• Supported Editors: VS Code, Neovim, Vim (zenc.vim), Zed, and any LSP-capable editor.

Use zc lsp to start the server.

Debugging Zen C

Zen C programs can be debugged using standard C debuggers like LLDB or GDB.

Visual Studio Code

For the best experience in VS Code, install the official Zen C extension. For debugging, you can use the C/C++ (by Microsoft) or CodeLLDB extension.

Add these configurations to your .vscode directory to enable one-click debugging:

tasks.json (Build Task):

{
    "label": "Zen C: Build Debug",
    "type": "shell",
    "command": "zc",
    "args": [ "${file}", "-g", "-o", "${fileDirname}/app", "-O0" ],
    "group": { "kind": "build", "isDefault": true }
}

launch.json (Debugger):

{
    "name": "Zen C: Debug (LLDB)",
    "type": "lldb",
    "request": "launch",
    "program": "${fileDirname}/app",
    "preLaunchTask": "Zen C: Build Debug"
}

Compiler Support & Compatibility

Zen C is designed to work with most C11 compilers. Some features rely on GNU C extensions, but these often work in other compilers. Use the --cc flag to switch backends.

zc run app.zc --cc clang
zc run app.zc --cc zig

Test Suite Status

Click to view Compiler Support details

Compiler	Pass Rate	Supported Features	Known Limitations
GCC	100% (Full)	All Features	None.
Clang	100% (Full)	All Features	None.
Zig	100% (Full)	All Features	None. Uses zig cc as a drop-in C compiler.
TCC	98% (High)	Structs, Generics, Traits, Pattern Matching	No Intel ASM, No __attribute__((constructor)).

[!WARNING] COMPILER BUILD WARNING: While Zig CC works excellently as a backend for your Zen C programs, building the Zen C compiler itself with it may verify but produce an unstable binary that fails tests. We recommend building the compiler with GCC or Clang and using Zig only as a backend for your operational code.

Building with Zig

Zig's zig cc command provides a drop-in replacement for GCC/Clang with excellent cross-compilation support. To use Zig:

# Compile and run a Zen C program with Zig
zc run app.zc --cc zig

# Build the Zen C compiler itself with Zig
make zig

C++ Interop

Zen C can generate C++-compatible code with the --cpp flag, allowing seamless integration with C++ libraries.

# Direct compilation with g++
zc app.zc --cpp

# Or transpile for manual build
zc transpile app.zc --cpp
g++ out.c my_cpp_lib.o -o app

Using C++ in Zen C

Include C++ headers and use raw blocks for C++ code:

include <vector>
include <iostream>

raw {
    std::vector<int> make_vec(int a, int b) {
        return {a, b};
    }
}

fn main() {
    let v = make_vec(1, 2);
    raw { std::cout << "Size: " << v.size() << std::endl; }
}

[!NOTE] The --cpp flag switches the backend to g++ and emits C++-compatible code (uses auto instead of __auto_type, function overloads instead of _Generic, and explicit casts for void*).

CUDA Interop

Zen C supports GPU programming by transpiling to CUDA C++. This allows you to leverage powerful C++ features (templates, constexpr) within your kernels while maintaining Zen C's ergonomic syntax.

# Direct compilation with nvcc
zc run app.zc --cuda

# Or transpile for manual build
zc transpile app.zc --cuda -o app.cu
nvcc app.cu -o app

CUDA-Specific Attributes

Attribute	CUDA Equivalent	Description
@global	__global__	Kernel function (runs on GPU, called from host)
@device	__device__	Device function (runs on GPU, called from GPU)
@host	__host__	Host function (explicit CPU-only)

Kernel Launch Syntax

Zen C provides a clean launch statement for invoking CUDA kernels:

launch kernel_name(args) with {
    grid: num_blocks,
    block: threads_per_block,
    shared_mem: 1024,  // Optional
    stream: my_stream   // Optional
};

This transpiles to: kernel_name<<<grid, block, shared, stream>>>(args);

Writing CUDA Kernels

Use Zen C function syntax with @global and the launch statement:

import "std/cuda.zc"

@global
fn add_kernel(a: float*, b: float*, c: float*, n: int) {
    let i = thread_id();
    if i < n {
        c[i] = a[i] + b[i];
    }
}

fn main() {
    def N = 1024;
    let d_a = cuda_alloc<float>(N);
    let d_b = cuda_alloc<float>(N); 
    let d_c = cuda_alloc<float>(N);
    defer cuda_free(d_a);
    defer cuda_free(d_b);
    defer cuda_free(d_c);

    // ... init data ...
    
    launch add_kernel(d_a, d_b, d_c, N) with {
        grid: (N + 255) / 256,
        block: 256
    };
    
    cuda_sync();
}

Standard Library (std/cuda.zc)

Zen C provides a standard library for common CUDA operations to reduce raw blocks:

import "std/cuda.zc"

// Memory management
let d_ptr = cuda_alloc<float>(1024);
cuda_copy_to_device(d_ptr, h_ptr, 1024 * sizeof(float));
defer cuda_free(d_ptr);

// Synchronization
cuda_sync();

// Thread Indexing (use inside kernels)
let i = thread_id(); // Global index
let bid = block_id();
let tid = local_id();

[!NOTE] Note: The --cuda flag sets nvcc as the compiler and implies --cpp mode. Requires the NVIDIA CUDA Toolkit.

C23 Support

Zen C supports modern C23 features when using a compatible backend compiler (GCC 14+, Clang 14+, TCC (partial)).

• auto: Zen C automatically maps type inference to standard C23 auto if __STDC_VERSION__ >= 202300L.
• _BitInt(N): Use iN and uN types (e.g., i256, u12, i24) to access C23 arbitrary-width integers.

Objective-C Interop

Zen C can compile to Objective-C (.m) using the --objc flag, allowing you to use Objective-C frameworks (like Cocoa/Foundation) and syntax.

# Compile with clang (or gcc/gnustep)
zc app.zc --objc --cc clang

Using Objective-C in Zen C

Use include for headers and raw blocks for Objective-C syntax (@interface, [...], @"").

//> macos: framework: Foundation
//> linux: cflags: -fconstant-string-class=NSConstantString -D_NATIVE_OBJC_EXCEPTIONS
//> linux: link: -lgnustep-base -lobjc

include <Foundation/Foundation.h>

fn main() {
    raw {
        NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
        NSLog(@"Hello from Objective-C!");
        [pool drain];
    }
    println "Zen C works too!";
}

[!NOTE] Note: Zen C string interpolation works with Objective-C objects (id) by calling debugDescription or description.

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Contributing

We welcome contributions! Whether it's fixing bugs, adding documentation, or proposing new features.

Please see CONTRIBUTING.md for detailed guidelines on how to contribute, run tests, and submit pull requests.

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Security

For security reporting instructions, please see SECURITY.md.

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Attributions

This project uses third-party libraries. Full license texts can be found in the LICENSES/ directory.

• cJSON (MIT License): Used for JSON parsing and generation in the Language Server.
• zc-ape (MIT License): The original Actually Portable Executable port of Zen-C by Eugene Olonov.
• Cosmopolitan Libc (ISC License): The foundational library that makes APE possible.
• TRE (BSD License): Used for the regular expression engine in the standard library.
• zenc.vim (MIT License): The official Vim/Neovim plugin, primarily authored by davidscholberg.

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