Credence.Pattern.NoReduceWhileWithoutHalt (credence v0.7.0)

Detects Enum.reduce_while/3 where every callback clause returns only {:cont, value} — never :halt or {:halt, value}. This is equivalent to plain Enum.reduce/3 and the reduce_while adds unnecessary ceremony.

Bad

Enum.reduce_while(list, 0, fn x, acc ->
  {:cont, acc + x}
end)

list
|> Enum.reduce_while({0, []}, fn h, {max, acc} ->
  new_max = max(h, max)
  {:cont, {new_max, [new_max | acc]}}
end)

Good

Enum.reduce(list, 0, fn x, acc ->
  acc + x
end)

list
|> Enum.reduce({0, []}, fn h, {max, acc} ->
  new_max = max(h, max)
  {new_max, [new_max | acc]}
end)

Auto-fix

Replaces reduce_while with reduce and unwraps each {:cont, value} return to just value.