DEV Community

Federico Ponzi
Federico Ponzi

Posted on

TLA+ is easy if you know how to abstract

I've been wanting to learn TLA+ for a while now, and I finally had a chance to do it thanks to a seminar series held by Professor Murat Demirbas. In this article, I will talk about my experience with formal methods and TLA+, and I will also share some of the things I've learnt that I think will be very useful when writing your specifications.

By the end of this article, I hope that you will:

Have a basic understanding of formal methods and model checking
Understand how TLA+ can improve algorithm and system design
Have some intuition on what it takes to write a spec in TLA+
Want to learn some TLA+.
Enter fullscreen mode Exit fullscreen mode

As always, let's start with the problem we're trying to solve.
What problem do formal methods help solve?

English is considered a very ambiguous language. When we build a complex system, we need an unambiguous specification (also known as "spec"). Formal methods use math to define a rigorous system model. After we have written the code for the model, we can then also use it to verify some properties.

The benefits of formal methods are twofold:

Unambiguous specification of our systems and algorithms
Verification of properties for these models
Enter fullscreen mode Exit fullscreen mode

An example of a property that can be verified is that no execution can result in a deadlock. This would be very difficult to prove in a test, especially if it spans multiple systems.

We can also verify that an algorithm is correct by writing some properties as invariants. An invariant is simply a predicate that should always hold true. Invariants are sometimes used in asserts.

We can define correctness and liveness properties. For example, we could verify that eventually some property will hold, such as that our new sorting algorithm eventually sorts its input.

Formal methods allow you to explore different designs and optimize performance while maintaining confidence that the system is doing the right thing.

Continue reading...

Image of Timescale

Timescale – the developer's data platform for modern apps, built on PostgreSQL

Timescale Cloud is PostgreSQL optimized for speed, scale, and performance. Over 3 million IoT, AI, crypto, and dev tool apps are powered by Timescale. Try it free today! No credit card required.

Try free

Top comments (0)

Heroku

Simplify your DevOps and maximize your time.

Since 2007, Heroku has been the go-to platform for developers as it monitors uptime, performance, and infrastructure concerns, allowing you to focus on writing code.

Learn More

👋 Kindness is contagious

Discover a treasure trove of wisdom within this insightful piece, highly respected in the nurturing DEV Community enviroment. Developers, whether novice or expert, are encouraged to participate and add to our shared knowledge basin.

A simple "thank you" can illuminate someone's day. Express your appreciation in the comments section!

On DEV, sharing ideas smoothens our journey and strengthens our community ties. Learn something useful? Offering a quick thanks to the author is deeply appreciated.

Okay