Service that allows to concatenate several RSS feeds into one. Multiple concatenated feeds can be served on different URLs.

• Why?
  I like to use RSS to get some kind of info that updates regulary. And sometimes it's usefull to have several similar feeds to be represented as one feed. I used several online services for these, but all of them have either some limitations or downtimes. So I decided to create simple application that provides such service and I don't need to rely on 3rd party services.
• Why Haskell?
  Why not? :)
  I don't use Haskell for my everyday tasks. In fact I never used it for anything except for examples from Learn You a Haskell for Great Good. So I decided to check if I know it good enough to write some simple application. This one is a good fit. It's not too complex. And, at the same time, it includes such common things as network (web) server, client, file reading, markup language parsing.
• Can I use it as example of good Haskell app?
  You probably should not. As it is mentioned above, this is my first Haskell app, and I believe that it has a lot of things that can be improved.

• Download
• Build with stack
• Create config file. Use config.example.yaml for reference.
• Run rssconcat from build directory (or stack exec rssconcat) with one optional argument - path to config file. If run without arguments, it looks for config.yaml file in current working directory.
• Go to http://YOUR_HOST:YOUR_PORT/ for list of availabled feed or add http://YOUR_HOST:YOUR_PORT/YOUR_FEED_NAME directly to your RSS reader.

• Cover with tests.
• Handle incorrect config file.
• Handle errors when retrieving from source feeds.
• Support for <link> RSS chanel field as required by specification
  For example: add new URL like /feed_name/info, which contains simple text like:

  This is feed that combines the following feeds: list of links from source feeds <link> fields

• Put better description in <description> RSS chanel field. Probably with the same content as described above.
• Support different feed types (RSS1/RSS2/Atom).
• ???
• PROFIT!

PRs are welcome. Also I would really appreciate, if your PR contains not only description of what is changed, but also why. E.g.: this PR changes usage of & function to $ because former is considered confusing and against Haskell best practices. Such comments will help me to learn Haskell better.