F# – Imitating Erlang’s bit syntax for easier binary protocol implementation

Bit Syntax in Erlang

One of the often under-appreciated features of Erlang is its Bit Syntax for parsing and pattern matching binary data at a bit level. For instance, to pare TCP segments you can write something along the line of:



The same capability can be applied to anything binary protocols, such as video encoding, imaging, or UDP.


Imitating with F# Computation Expressions



Whilst this capability is not built into F#, or any other language that I know of for that matter, we do have a very powerful, and robust feature in F# in Computation Expressions.

With computation expressions, I was able to create a small library that allows you to write and read data to and from a stream at a bit level. With the bitWriter and bitReader workflows you will be able to write and parse TCP headers with code like the following:


The library is available via Nuget:

please give it a try, and let me know if you find any bugs here.


p.s. there is still much work to be done on the library. For instance, it’s allocating a new buffer array for each workflow rather than using a buffer pool. If you find this library useful and in need for greater performance, please feel free to contribute and help improve the performance of this library.

Enjoy what you’re reading? Subscribe to my newsletter and get more content on AWS and serverless technologies delivered straight to your inbox.

Yan Cui

I’m an AWS Serverless Hero and the author of Production-Ready Serverless. I have run production workload at scale in AWS for nearly 10 years and I have been an architect or principal engineer with a variety of industries ranging from banking, e-commerce, sports streaming to mobile gaming. I currently work as an independent consultant focused on AWS and serverless.

You can contact me via Email, Twitter and LinkedIn.

Hire me.

Check out my new course, Complete Guide to AWS Step Functions.

In this course, we’ll cover everything you need to know to use AWS Step Functions service effectively. Including basic concepts, HTTP and event triggers, activities, design patterns and best practices.

Get Your Copy