The Language of Nine-Nines Reliability
While newer languages like Elixir have brought a more modern syntax to the BEAM virtual machine, Erlang remains the original and undisputed king of fault tolerance. Born at Ericsson in the 1980s to build telephone exchanges that could never go down, its design philosophy is rooted in a single, powerful idea: building systems that can handle failure as a normal part of operation. This is achieved through lightweight, isolated processes, asynchronous message passing, and the powerful supervision trees of the Open Telecom Platform (OTP).
Hiring an Erlang developer is not about hiring a programmer; it is about hiring a system design architect who thinks in terms of concurrency, distribution, and fault tolerance from the ground up. This is a fundamentally different mindset from almost any other programming paradigm. This playbook explains how Axiom Cortex vets for this rare and valuable expertise.
How Axiom Cortex Evaluates Erlang Developers
Vetting for Erlang requires a focus on the core principles that make the BEAM unique. We test for a deep, intuitive understanding of the Actor model and OTP.
Dimension 1: OTP and the Actor Model
This is the heart of Erlang. A candidate must demonstrate mastery of:
- Processes and Messaging: Can they explain how Erlang's lightweight processes enable massive concurrency? Can they design a system based on asynchronous message passing?
- Supervisors and GenServers: Can they design a supervision tree to create a self healing system? Can they correctly implement a `gen_server` to manage state?
Dimension 2: Concurrency and Distribution
Erlang was built for distribution. This dimension tests a candidate's ability to build systems that span multiple nodes.
- Node Communication: Do they understand how Erlang nodes communicate and how to handle network partitions ("netsplits")?
- Pattern Matching: Can they use Erlang's powerful pattern matching in function heads and `case` expressions to write clean, declarative, and safe concurrent code?
The Bedrock of Ultra-Reliable Systems
When you staff your team with engineers who have passed the Erlang Axiom Cortex assessment, you are investing in a team that can build systems with a level of reliability and fault tolerance that is orders of magnitude beyond what is possible with traditional languages. They will build the kind of "five-nines" (99.999% uptime) systems that power the world's most critical infrastructure, from messaging apps like WhatsApp to financial trading platforms. For modern functional programming on the BEAM, see our playbook for Elixir. For other functional languages, consider our vetting for Haskell or Scala.