On Thu, Sep 2, 2010 at 6:49 PM, Daniel Fischer
On Friday 03 September 2010 00:17:22, Alec Benzer wrote:
I guess I'm still sort of confused or perturbed with why it's disabled by default. If the compiler has the ability to do it and there are no problems with doing it, why not just allow it without requiring you to pass a flag to the compiler?
It's disabled by default because the language standard laid down different rules. Generally, compiler writers tend to avoid enabling too much non- standard behaviour by default (though chapter 12 of the GHC user's guide lists a couple of deviations). However, often there's useful stuff that goes against the standard (well, it seemed to be a good idea at the time), so many compilers offer extensions to go beyond the standard.
I guess I would then be concerned with why they didn't allow it in the standard (though I guess "well, it seemed to be a good idea at the time" answers that). I think I also would want to avoid doing things not in the language standard on principle, since my instinct would tell me that if only a particular compiler implements, I shouldn't use it because it'll produce non-standard code. Though this sort of comes comes from C/C++ where there are different compilers on different platforms, but I guess with haskell people pretty much use ghc everywhere?