libghc-happstack-doc 7.0.1-2build4 (i386 binary) in ubuntu trusty

 Happstack is a web framework written in Haskell; it provides a rich
 collection of types and functions for routing Requests, generating
 Responses, working with query parameters, form data, and cookies,
 serving files and more.
 This package provides the documentation for a library for the Haskell
 programming language.
 See http://www.haskell.org/ for more information on Haskell. Anyway, it is just a
 stub, depending on the package that actually provides the Happstack
 server.