Andy Balholm <andybalh...@gmail.com>:
> A good translation from C to Go needs to look as much like the original,
> un-preprocessed C source as possible. But a powerful translation tool will
> probably need to preprocess, parse, and typecheck the code, while keeping
> track of the source location that everything corresponds to—and then use that
> information to guide the translation.
Perry and I have two different target languages in mind. Perry's
target language is basically a repaired C - type-safe, almost
upward-compatible. He and I have the same strategic goal - draining
the swamp of old, leaky C code - we're just betting on slightly
different ways to do it. We intend to cooperate as much as possible.
But for both of them our intended strategy is *not* to preprocess.
Instead, we're willing to accept that some abuses of the preprocessor
need to be punted to a human, but treat other uses as part of the
parse tree.
For example if you have a set of #defines each of which expands to a
syntactically well-formed C expression. it seems clear to us that the
right thing is to recognize this and map them to const and func
declrations, checking for and throwing an error on capture of any
identifier that isn't a defined global.
We're willing to throw an error on that, or on syntactically
ill-formed macro expansion because we're not aiming for a completely
perfect mechanized trannlation. We know this is impossible in the
general case. Instead, our goal is just to get punt-to-a-human
frequency low enough that very large translations are practical with a
relatively small amount of human effort.
We don't mind requiring users to make point changes to C codebases to
get them through the translator when the code was horrible in C in
the first place.
As for unions, we'll do the stupidest possible thing that can work -
translate them to structs and throw a warning. If the union was just
a space optimization, that's it. If not, then a human must intervene.
(Both projects are contingent on funding we don't yet have, alas.
It's not like we need to buy a cyclotron or anything but we do need to
be able to eat and pay rent for a couple years each.)
It would sure help if Go had sum types. Has there been any discussion
of adding these?
--
<a href="http://www.catb.org/~esr/";>Eric S. Raymond</a>
My work is funded by the Internet Civil Engineering Institute: https://icei.org
Please visit their site and donate: the civilization you save might be your own.
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