haskell-mode software package provides major mode for editing Haskell in Emacs, you can install in your Debian 8 (Jessie) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install haskell-mode
haskell-mode is installed in your system.
Make ensure the haskell-mode package were installed using the commands given below,
$ sudo dpkg-query -l | grep haskell-mode *
You will get with haskell-mode package name, version, architecture and description in a table
| Distro | Debian 8 jessie |
| Section | Haskell |
| Package | haskell-mode |
| Version | 13.10-3 |
| Description | major mode for editing Haskell in Emacs |
| Sub Section | Haskell |