Erlang

Erlang powered WhatsApp and the telecom backbone. OTP 27 (2024) adds a JSON module and triple-quoted strings. It is the foundation of Elixir.

When to Use

• 99.9999999% Reliability: Hot code reloading, supervision trees.
• Massive Concurrency: Lightweight processes (millions per node).
• Distributed Systems: Distributed Erlang nodes connect natively.

Core Concepts

OTP

Open Telecom Platform. Behaviors like gen_server (Generic Server).

Let it Crash

Don't catch exceptions. Let the supervisor restart the process.

Message Passing

Pid ! Message. No shared memory.

Best Practices (2025)

Do:

• Use rebar3: The standard build tool.
• Use maybe: The new monadic-like flow control (enabled by default in 27).
• Use json: The new stdlib JSON parser (faster/safer).

Don't:

• Don't optimize pre-maturely: Profile first. Messages are copied.

References

• Erlang.org