ghc software package provides The Glasgow Haskell Compilation system, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install ghc
ghc is installed in your system.
Make ensure the ghc package were installed using the commands given below,
$ sudo dpkg-query -l | grep ghc *
You will get with ghc package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Haskell |
| Package | ghc |
| Version | 7.10.3-10 |
| Description | The Glasgow Haskell Compilation system |
| Sub Section | Haskell |