Here is a ghci session with the attached program:
> ghci B
___ ___ _
/ _ \ /\ /\/ __(_)
/ /_\// /_/ / / | | GHC Interactive, version 6.4.2, for Haskell 98.
/ /_\\/ __ / /___| | http://www.haskell.org/ghc/
\____/\/ /_/\____/|_| Type :? for help.
Loading package base-1.0 ... linking ... done.
Compiling C[boot] ( ./C.hs-boot, ./C.o-boot )
Compiling A ( ./A.hs, interpreted )
Compiling B ( B.hs, interpreted )
Compiling C ( ./C.hs, interpreted )
Ok, modules loaded: C, B, A, C.
*C> :r
Ok, modules loaded: A, C, B.
*A> :m + B
*A B> A
During interactive linking, GHCi couldn't find the following symbol:
B_zdfClass1B_closure
This may be due to you not asking GHCi to load extra object files,
archives or DLLs needed by your current session. Restart GHCi, specifying
the missing library using the -L/path/to/object/dir and -lmissinglibname
flags, or simply by naming the relevant files on the GHCi command line.
Alternatively, this link failure might indicate a bug in GHCi.
If you suspect the latter, please send a bug report to:
glasgow-haskell-bugs@haskell.org
*A B> B
B
*A B> A
A
3 strange things happen:
1. I ask to load B, it loads C
2. I ask to reload, it loads A :)
3. missing symbol error which goes away after evaluating some other expression
