Haskell projects to study and learn from? [closed]

Question

As a developer who is new to Haskell, I am looking for open-source Haskell applications that I could study and learn from.

In particular, I am looking for open-source projects that show:

• How to write network servers that scale well, with low response latencies and high throughput.
  The Warp webserver would perhaps be an example here, are there any others?
• Applications showing techniques for keeping memory use low, or showing examples of GC-friendly design.
• Projects that showcase techniques for testing Haskell applications (related question: haskell-testing-workflow).
• Programs designed for running well on multi-core systems.

What open-source projects would you recommend as exemplars of modern Haskell programming?

Related SO question: good-haskell-source-to-read-and-learn-from.

Answer 1

As far as network servers go, I suggest reading Mighttpd – a High Performance Web Server in Haskell by Kazu Yamamoto, from issue 19 of the Monad.Reader; it uses Warp under the hood and can achieve speeds exceeding that of nginx(!). That same issue also has an article about Haskell-MPI, so it's relevant for multi-core programming too.

The xmonad source code is frequently recommended (e.g. in the related question you linked), as it is a widely-used, stable piece of "real-world" software with an unusual amount of care and attention paid to good Haskell design.