IntroducedNameIsUsed

Report unused module-defined variables, ports, type aliases, let-defined variables, pattern variables including punned fields and dependencies.

Unused imports, import aliases, import exposes and module exposes are allowed; reporting these would be more annoying than helpful.

reported

function unusedArgument =
    ""

not reported

function _unusedArgument =
    ""

potential future improvements

• report unused variants. While possible, it would have false negatives (e.g. when constructing a variant for equality checking) and impossible to fix as deciding which cases to remove from a when is often requires exhaustiveness analysis.
• report unused fields. This may require type inference or similar
• unused function parameters. When a function ignores an incoming value, remove the corresponding argument in all call sites. Fixing this is non-trivial and the check is probably more controversial compared to the remaining unused checking
• report phantom type parameters. Also probably too controversial, can be a separate check
• report unused parameters across (mutual) recursion (in module- and let-defined variables). This is tricky! Help appreciated