No Used Ignored Variables

Declared anonymous variables (prefixed with _) should not be used.

Avoid

_Ignored = some_function(),
do_something(_Ignored).

Prefer

Value = some_function(),
do_something(Value)

Rationale

In Erlang, variables prefixed with an underscore (e.g., _Var) are conventionally treated as "ignored" or "don't care" values, signaling that they are unused. However, using these variables in later expressions (e.g., passing _Var to a function or matching against it) contradicts their intended purpose and misleads both the compiler and human readers.

This can confuse maintainers, as _Var appears to be intentionally ignored, and also introduce subtle bugs or overlooked logic due to mistaken assumptions about variable usage.

Options

• None.

Example configuration

{elvis_style, no_used_ignored_variables, #{}}