[SatyajitSarangi]

Thanks for this list.

I was mostly looking for Python, Javascript, Haskell and C#. Any help regarding that?

Also, as I believe this thread will also help others, you can go ahead and post about any other code-bases for other languages.

[timClicks]

Modules within the Python standard library are very well written. The source code also provides very good examples of decent unit tests.

[gatehouse]

Agreed.

Here is a link to cpython 2.7 libraries: http://hg.python.org/cpython/file/70274d53c1dd/Lib

Those that are implemented in C are in the "Modules" folder from the top level.

I think you [OP] will get the most benefit from reading libraries that you use often because it will give you some direction.

If there are 3rd party libraries you use heavily those will be interesting too.

It is very very difficult to just pick up megabytes of code and start reading them and find it useful. You will be able to pick up style and conventions but not really high-level engineering decisions.

My suggestion is to take software that you use regularly and run it through a debugger. Since you use it you know the problem domain. And with the debugger the code you're reading gets real context. I've done this with Git for example.

And also look at the design documents for big OSS projects.

[AnkhMorporkian]

I would stay the heck away from the collections and itertools modules to be honest. Raymond H. is an amazing coder, but he' s a madman.

[sophacles]

For C# i found the disruptor.net code to be very nice. It's mostly a direct port of disruptor from java - but it definitely was pretty nice to read through.

[egonschiele]

For Haskell, Hakyll's source is pretty well written.

[nubela]

requests module is very well written