On Tue, 19 Mar 2019 15:52:41 +0100
Ricardo Wurmus <rekado@elephly.net> wrote:

> Using the full file name would work, for example:
> 
> ./pre-inst-env guix environment --ad-hoc python zlib -- \
>     python3 -c "import os; import ctypes;
> libz=ctypes.CDLL(os.environ['GUIX_ENVIRONMENT']+'/lib/libz.so.1')"

Right! With a "substitute*", I can inject the full path and then it
works.

Thanks,

Björn