language-extension

I have had the experience a few times now of having GHC tell me to use an extension, only to discover that when in using that extension I have made code far more complex when a simple refactor would have allowed me to stick with Haskell 98 (now 2010 ) and have a more straightforward solution. On the other hand, there are also times when GADT's or Rank2Types (rarely RankNTypes) make for much less work and much cleaner code. Which extensions tend generally to obscure the possibility of a better design, and which generally improve it? If there are some that do both, what should a user look for

I was just doing some Haskell development and I recompiled some old code on a new version of GHC: The Glorious Glasgow Haskell Compilation System, version 7.2.1 And when I did I received the following error: Warning: -XDatatypeContexts is deprecated: It was widely considered a misfeature, and has been removed from the Haskell language. That appears when you have code in the following format: data Ord a => MyType a = ConstructorOne a = ConstructorTwo a a My question is: Why was this feature deprecated in the first place and what am I supposed to do instead to achieve the same or similar

I just discovered this old C++0x draft about modules in C++0x. The idea was to get out of the current .h/.cpp system by writing only .cpp files which would then generate module files during compilation, which would then in turn be used by the other .cpp files. This looks like a really great feature. But my question is: why did they remove it from C++0x? Was it because of too many technical difficulties? Lack of time? And do you think they will consider working on it for an ulterior version of C++? From the State of C++ Evolution (Post San Francisco 2008) , the Modules proposal was categorized