I think I'm convinced. Trying to make the format stay consistent has
been the major thing that has slowed me down. The current syntax
doesn't include all of the information contained in the iface data
types, and inferring the missing bits is rather tricky. I had thought
that inference of the missing details was possible, because some of
what's in the internal data types is slightly redundant (in order to
simplify much of the rest of GHC's code) but I'm getting to the point
where I'm not quite sure.
So, yeah, perhaps External Core should be essentially a textual
representation of a .hi file.
Beyond the details of function and type declarations, there's some
other information that External Core never seemed to be designed to
contain, but which might be useful. Class information, for instance,
is currently missing, but is crucial in order to link Haskell code to
External Core code for which the original Haskell source is unavailable.
Aaron
On Jul 2, 2007, at 11:38 AM, Neil Mitchell wrote:
Backward compatibility got broken a while ago, since GHC Core
currently doesn't seen to work. Given that you haven't got a slew of
complaints when it got broken, I think you can assume that backward
compatibility isn't that important.
The main reason I'd been avoiding the
Read/Show approach is that it would make the External Core format
change whenever the .hi format changes
You have two choices:
1) Define a constant format, and then every time the .hi format
changes update the output translator. This requires ongoing
maintenance over a long time period. If this breaks, users will be
unable to work with GHC Core anymore.
2) Use Read/Show based stuff. Every time the .hi format changes people
may need to rework their program (unlikely) and will need to update
their .hcr files. This gives you almost no ongoing maintenance.
(1) is nicer for a user, but only if you guarantee it is going to be
actively maintained. If there is any doubt about this, (2) would be
preferable. Yhc uses a combination - a separate abstract syntax tree,
but read/show off that.
Thanks
Neil
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