View Source Credo.Check.Warning.UnusedRegexOperation (Credo v1.7.5)


This check is enabled by default.

Learn how to disable it via .credo.exs.

This check has a base priority of high and works with any version of Elixir.


The result of a call to the Regex module's functions has to be used.

While this is correct ...

def extract_username_and_salute(regex, string) do
  [string] =, string)

  "Hi #{string}"

... we forgot to save the downcased username in this example:

def extract_username_and_salute(regex, string) do, string)

  "Hi #{string}"

Regex operations never work on the variable you pass in, but return a new variable which has to be used somehow.

Check-Specific Parameters

There are no specific parameters for this check.

General Parameters

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Parameters can be configured via the .credo.exs config file.