I'm referring to the SML/NJ language port in <portsroot>/lang/sml-nj:
# $FreeBSD: ports/lang/sml-nj/Makefile,v 1.14 2002/07/01 08:53:03 jkoshy Exp $


I have encountered now the problem that when opening a module,
the sml/nj system desired to recompile certain files, which were
not available anymore, since the respective ports directory had
undergone a "make clean" in the meantime.

The responsible ports maintainer probably hasn't seen this before
either (although I don't want to preempt him/her on this) and I
don't think it's trivial to fix.

Fix: 

A workaround (not tested right now) might be to leave the "work" dir
in the ports directory around and open all such structures as the
user owning the ports tree, and reinstalling the port once more
afterwards.
How-To-Repeat: 
Start the sml/nj interactive system by running the "sml" command and
try to open the SplayTree structure (or use it by any other means):


Standard ML of New Jersey, Version 110.0.7, September 28, 2000 [CM; autoload enabled]
- open SplayTree;
[Autoloading...]
!% CM Warning: need to recompile /usr2/ports/lang/sml-nj/work/src/smlnj-lib/Util/splaytree-sig.sml (even though it is `stable')
[compiling /usr2/ports/lang/sml-nj/work/src/smlnj-lib/Util/splaytree-sig.sml (stable) -> /usr2/ports/lang/sml-nj/work/src/smlnj-lib/Util/CM/x86-unix/splaytree-sig.sml.bin]

uncaught exception Io: openIn failed on "/usr2/ports/lang/sml-nj/work/src/smlnj-lib/Util/splaytree-sig.sml", No such file or directory
  raised at: boot/IO/text-io-fn.sml:796.25-796.71
	     sched/recompile.sml:206.38-206.41
-