Major part of the BazQux Reader sources. Excludes configuration files (nginx, ElasticSearch, utilities), static assets (images and commercial fonts) and few source code files (Config.hs with API keys and few experimental files). It won't compile but it could give you an impression of what is going on.
Ur/Web part of sources is located in the root and
lib folder. Haskell part is in
crawler folder (historic name, frontend is using Haskell as well).
Code is quite ugly (quick and dirty hacks, experiments, legacy, Russian comments or no comments at all). But it's a working code used everyday by thousands of people. Some parts are left untouched from the crazy 2013 spring when Google decided to close Google Reader and I needed to do many-many things in 3 months. Some parts are newer and are more readable.
Posts about my experience (a bit dated):
Ur/Web <=> Haskell interface
If you like to make mixed Ur/Web+Haskell app look into
Executable Reader part).
lib contains Ur/Web implementation of Haskell Binary package (Haskell function arguments and results are serialized using Binary).
copy_cc is a substitute for the real GNU gcc which is called from
urweb compiler and copies
webapp.c file so it will be compiled and linked later in GHC.
crawler/Gen.hs contains description of data types from which both Ur/Web and Haskell data types and serialization functions are generated. It also generates helper Riak funtions for data types stored in Riak and FFI bindings for Haskell functions called from Ur/Web part. It's not a ready to use library but rather the script you must edit.