Problem with ghc-6.5.20061008 on Mac OS X Intel

Aaron Tomb atomb at
Mon Oct 9 21:10:02 EDT 2006

Hi Deborah,

The first thing that springs to mind is that the mtl library (which  
contains Control.Monad.State, the source of the link errors below)  
isn't included in the 20060915 binary distribution, though it should  
be easy to check it out and compile it separately. So, the question  
is, why does it get all the way to link time before noticing that the  
library isn't available?

It's possible that one version of GHC is trying to use object or  
library files created by another version. I came across that problem  
myself, at one point. You might check that only one copy of the  
ghc-6.5/lib/ directory exists anywhere that GHC might find it.

When you say "this didn't happen before", do you mean that the  
20060915 build can compile example25.hs, but trying to compile it  
with your own build of 20061008 fails as you've described?

By the way, does readline  work for you with the ghci from the  
20060915 binary distribution, and just not with the version you  
compiled yourself? I ask because one of the people I was talking to  
as I build the distribution had trouble with it.


On Oct 9, 2006, at 5:42 PM, Deborah Goldsmith wrote:

> Hi,
> I was able to build this release using the 20060915 Intel build  
> that's available, on 10.4.8. ghci seems to work OK (except for  
> Readline), but an attempt to compile gives:
> $ ghc example25.hs
> /usr/bin/ld: Undefined symbols:
> _mtlzm1zi0_ControlziMonadziState_evalStateT_closure
> _mtlzm1zi0_ControlziMonadziState_gets_closure
> _mtlzm1zi0_ControlziMonadziState_zdf1_closure
> _mtlzm1zi0_ControlziMonadziState_zdf7_closure
> _mtlzm1zi0_ControlziMonadziState_zdf9_closure
> _mtlzm1zi0_ControlziMonadziWriter_zdf5_closure
> _mtlzm1zi0_ControlziMonadziWriter_zdf7_closure
> collect2: ld returned 1 exit status
> This didn't happen before.
> Any ideas? Am I doing something wrong, or is there something wrong  
> with the 20061008 snapshot?
> Thanks,
> Deborah
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