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What is Codon?

Codon is a high-performance Python compiler that compiles Python code to native machine code without any runtime overhead. Typical speedups over Python are on the order of 10-100x or more, on a single thread. Codon's performance is typically on par with (and sometimes better than) that of C/C++. Unlike Python, Codon supports native multithreading, which can lead to speedups many times higher still. Codon grew out of the Seq project.

Examples

Codon is a Python-compatible language, and many Python programs will work with few if any modifications:

def fib(n):
    a, b = 0, 1
    while a < n:
        print(a, end=' ')
        a, b = b, a+b
    print()
fib(1000)

The codon compiler has a number of options and modes:

# compile and run the program
codon run fib.py
# 0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987

# compile and run the program with optimizations enabled
codon run -release fib.py
# 0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987

# compile to executable with optimizations enabled
codon build -release -exe fib.py
./fib
# 0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987

# compile to LLVM IR file with optimizations enabled
codon build -release -llvm fib.py
# outputs file fib.ll

See the docs for more options and examples.

This prime counting example showcases Codon's OpenMP support, enabled with the addition of one line. The @par annotation tells the compiler to parallelize the following for-loop, in this case using a dynamic schedule, chunk size of 100, and 16 threads.

from sys import argv

def is_prime(n):
    factors = 0
    for i in range(2, n):
        if n % i == 0:
            factors += 1
    return factors == 0

limit = int(argv[1])
total = 0

@par(schedule='dynamic', chunk_size=100, num_threads=16)
for i in range(2, limit):
    if is_prime(i):
        total += 1

print(total)

Codon supports writing and executing GPU kernels. Here's an example that computes the Mandelbrot set:

import gpu

MAX    = 1000  # maximum Mandelbrot iterations
N      = 4096  # width and height of image
pixels = [0 for _ in range(N * N)]

def scale(x, a, b):
    return a + (x/N)*(b - a)

@gpu.kernel
def mandelbrot(pixels):
    idx = (gpu.block.x * gpu.block.dim.x) + gpu.thread.x
    i, j = divmod(idx, N)
    c = complex(scale(j, -2.00, 0.47), scale(i, -1.12, 1.12))
    z = 0j
    iteration = 0

    while abs(z) <= 2 and iteration < MAX:
        z = z**2 + c
        iteration += 1

    pixels[idx] = int(255 * iteration/MAX)

mandelbrot(pixels, grid=(N*N)//1024, block=1024)

GPU programming can also be done using the @par syntax with @par(gpu=True).

What isn't Codon?

While Codon supports nearly all of Python's syntax, it is not a drop-in replacement, and large codebases might require modifications to be run through the Codon compiler. For example, some of Python's modules are not yet implemented within Codon, and a few of Python's dynamic features are disallowed. The Codon compiler produces detailed error messages to help identify and resolve any incompatibilities.

Codon can be used within larger Python codebases via the @codon.jit decorator. Plain Python functions and libraries can also be called from within Codon via Python interoperability.

Install

Pre-built binaries

Pre-built binaries for Linux and macOS on x86_64 are available alongside each release. Download and install with:

/bin/bash -c "$(curl -fsSL https://exaloop.io/install.sh)"

Build from source

Codon can be built using CMake. It is recommended to build Codon with Clang, which can be done by setting the CC and CXX environment variables:

export CC=clang
export CXX=clang++

Most dependencies are built as part of the CMake build process, except for LLVM, which can be built as follows (note that Codon uses a custom fork of LLVM 15):

git clone --depth 1 -b codon https://github.com/exaloop/llvm-project
mkdir -p llvm-project/llvm/build
cd llvm-project/llvm/build
cmake .. \
    -DCMAKE_BUILD_TYPE=Release \
    -DLLVM_INCLUDE_TESTS=OFF \
    -DLLVM_ENABLE_RTTI=ON \
    -DLLVM_ENABLE_ZLIB=OFF \
    -DLLVM_ENABLE_TERMINFO=OFF \
    -DLLVM_TARGETS_TO_BUILD=all
make
make install

Finally, build Codon itself with:

cd codon
mkdir build
(cd build && cmake .. -DCMAKE_BUILD_TYPE=Release -DLLVM_DIR=$(llvm-config --cmakedir))
cmake --build build --config Release

Documentation

Please see docs.exaloop.io for in-depth documentation.