Unicode in GHC: need some advice on building

[Dimitry Golubovsky]

Hi,

Following up the discussion in Haskell-Cafe about ways to bring better 
Unicode support in GHC.

I may take care on putting this into the GHC runtime, but I need some 
advice as I am completely new to this.

What needs to be done primarily, is to replace the FFI calls made from 
GHC.Unicode (iswupper, islower etc.) with functions implemented directly 
in the runtime, or in an external library (independent from libc).

I tried to do this in two ways. First, I made a shared object containing 
substitutes for these functions (draft code, based on what I submitted 
for Hugs some time ago), and LD_PRELOADed it. Everything went fine, and 
my small test program worked both compiled to binary and in GHCi (it 
just coredumped when towlower/towupper was called on non-ASCII character 
without the substitution library).

Bad thing is, LD_PRELOAD does not work on all systems. So I tried to put 
the code directly into the runtime (where I believe it should be; the 
Unicode properties table is packed, and won't eat much space). I renamed 
foreign function names in GHC.Unicode (to avoid conflict with libc 
functions) adding u_ to them (so now they are u_iswupper, etc). I placed 
the new file into ghc/rts, and the include file into ghc/includes. I 
could not avoid messages about missing prototypes for u_... functions , 
but finally I was able to build ghc. Now when I compiled my test program 
with the rebuilt ghc, it worked without the LD_PRELOADed library. 
However, GHCi could not start complaining that it could not see these 
u_... symbols. I noticed some other entry points into the runtime like 
revertCAFs, or getAllocations, declared in the Haskell part of GHCi just 
as other foreign calls, so I just followed the same style - partly 
unsuccessfully.

Where am I wrong?

Another thing, this might be done without intervention into the sources, 
just as an external library. Which would be the best placement for the 
library, so it would load/compile in automatically?

I tried to find information in the GHC Commentary, but it did not give 
me much.

Dimitry Golubovsky
Middletown, CT