Include library source code in distribution
I suggest including source code for haskell libraries in the distribution (or to have additional distribution with sources). The source code would be a valuable learning resource for those who are starting to learn haskell.
It would be possible to examine what the function actually does. And it would be possible to replicate a patterns from the library in own code when the library functions or types do not provide a requested functionality.
Even simply providing the source code would be a great help. The partially provided source for core Java libraries was one of the reasons why Java has gained popularity so fast. But providing an easy ability to recompile haskell library sources on the spot will simplify a process of submitting small enhancements and bug-fixes and it will be more in the spirit of open source.