hlint is a command-line tool for suggesting improvements to Haskell code. It is designed to be highly configurable and extensible, and can be used to detect a wide range of issues, such as:
- Redundant or unnecessary code: hlint can detect code that is redundant or unnecessary, such as redundant imports, unused variables, or unnecessary parentheses.
- Inefficient code: hlint can detect code that is inefficient, such as patterns that may lead to performance issues, or code that can be simplified to improve readability.
- Code style issues: hlint can detect code that does not conform to recommended style guidelines, such as naming conventions, indentation, or use of specific language features.
hlint can be used in several ways:
- By running hlint on a single file, it will check the file and report any issues it finds.
- By running hlint on a directory, it will check all of the files in that directory and report any issues.
- By running hlint on a project, it will check all of the files in that project and report any issues.
hlint can also be integrated with various code editors, such as Vim, Emacs, or Atom, to provide suggestions while you are writing code. hlint is highly configurable and can be customized to suit your specific needs. It can be configured to ignore certain types of issues or to treat certain issues as errors rather than warnings. It’s important to note that hlint is not a compiler, it’s a linter, it does not check for any syntax error and it only suggests improvements, it’s up to the developer to decide whether to apply them or not.
If you encounter the below error while running the command hlint:
hlint: command not found
you may try installing the below package as per your choice of distribution:
| Distribution | Command |
|---|---|
| Debian | apt-get install hlint |
| Ubuntu | apt-get install hlint |
| Arch Linux | pacman -S hlint |
| Kali Linux | apt-get install hlint |
| Fedora | dnf install hlint |
| OS X | brew install hlint |
| Raspbian | apt-get install hlint |
hlint Command Examples
1. Display suggestions for a given file:
# hlint path/to/file options
2. Check all Haskell files and generate a report:
# hlint path/to/directory --report
3. Automatically apply most suggestions:
# hlint path/to/file --refactor
4. Display additional options:
# hlint path/to/file --refactor-options
5. Generate a settings file ignoring all outstanding hints:
# hlint path/to/file --default > .hlint.yaml