hlint:tldr:fdf05

This command is using the tool named "hlint" with two arguments: ${filename} and --refactor-options.

• hlint is a linting tool for Haskell code that analyzes Haskell source files and suggests improvements based on coding practices and standards.
• ${filename} is a placeholder representing the name of the file that you want to analyze with hlint. You would replace ${filename} with the actual name of your file when running the command.
• --refactor-options is an option that is passed to hlint to specify additional settings or configurations related to refactoring. Refactoring refers to modifying the existing code to improve its structure, readability, or efficiency.

By running this command, you are asking hlint to analyze the specified file (${filename}) and provide suggestions for code improvements using the specified refactor options. The exact behavior of the --refactor-options would depend on the specific configuration and settings of hlint.