Pattern matching in function heads and control-flow

Context

Pattern matching in function heads should be used exclusively for control flow and not as a convenient way to extract values out of maps or structs.

This helps indicate to the reader of the code that the pattern matching influences the control-flow of the code and as-such runtime behaviour.

This is also outlined in the official docs as an anti-pattern

Resolution

• You MUST pattern matching in function heads for control-flow purposes.
• You MUST NOT use pattern matching in function heads as a convenience for destructuring variables out into the function body.

Links

• https://hexdocs.pm/elixir/main/code-anti-patterns.html#complex-extractions-in-clauses