On Jan 11, 2008 8:13 PM, Jeremy Shaw
At Thu, 10 Jan 2008 22:16:27 -0200, Maurício wrote:
I tried google and ghc homepage, but could not find "elsewhere" :) Can you give me a link or somewhere to start from?
No. What I meant to say was, I'm not really sure myself, I just know there is a difference and -fno-implicit-prelude is more aggressive. I you do find a clear explaination, I would love to see it.
So, when you write the number 3 in Haskell, GHC converts this to essentially (Prelude.fromInteger (3::Integer)) in its internal format. So it doesn't matter if you import Prelude (), Prelude's version of fromInteger still gets called. If you give -fno-implicit-prelude, then this is converted to simply (fromInteger (3::Integer)), without the hard-coded prelude reference. That means you could write your own version of fromInteger that does something different. A common usage for -fno-implicit-prelude (insofar as it is used at all, which is seldom) is to replace the standard Num hierarchy with a saner one, with numeric literals resolving to that one instead. There are a few other hard-coded references to Prelude in the internal format, but I don't remember what they are offhand. -fno-implicit-prelude gets rid of those, too. Luke