The page: https://www.haskell.org/platform/ claims that haskell-platform comes with the Stack tool. However, on my Debian system after installing the haskell-platform package, I do not have the command stack available to me (which I would if I followed the instructions for installing Stack from the Stack website).
I can't find any information on how Stack is included in haskell-platform. It seems to be mentioned on the front page of the site, and no where else.
So, in what way is Stack "included" with the haskell-platform?
Haskell platform 2014.2.0 version doesn't come up with Stack. You can verify it from here: https://www.haskell.org/platform/contents.html
Haskell platform 8.0.1 is the first version which supports Stack. Also the versioning scheme of the platform seemed to change after 2014.2.0.
In my opinion, you should generally not try installing from Debian's package manager as it is usually quite old. Also, these days I would just recommend you to use Stack and install it from here.