libghc-free-dev software package provides Monads for free, 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 libghc-free-dev
libghc-free-dev is installed in your system.
Make ensure the libghc-free-dev package were installed using the commands given below,
$ sudo dpkg-query -l | grep libghc-free-dev *
You will get with libghc-free-dev package name, version, architecture and description in a table
| Distro | Debian 8 jessie |
| Section | Haskell |
| Package | libghc-free-dev |
| Version | 4.9-2+b6 [s390x], 4.9-2+b5 [am |
| Description | Monads for free |
| Sub Section | Haskell |