Re: Writing a Mac Ada compiler

[dewar@cs.nyu.edu (Robert Dewar)]

Mike, at this stage, I am afraid your lack of familiarity with compiler
technology is showing. Writing a lexical analyzer and parser for Ada is
by comparison with the rest of the task simple, but even these very
simple tasks are by no means trivial, especially if you want to get
any kind of decent error messages.

As for the idea that the only remaining step is generating machine language,
I am afraid it seems that your cource on compilers gave a rather false
impression. The hard part of an Ada compiler is the semantic analysis.

Developing a full Ada compiler with a code generator is indeed a difficult
project. The estimates of person years you see are for people with extensive
compiler experience. I would estimate that the time to complete such a project
for people without this kind of experience would be essentially infinite. You
would learn something trying, but you would have no chance of succeeding. If
that seems like a challenge, fine, as I say you will certainly learn something
trying.

As for porting GCC, this is a task that is probably about one twentieth the
effort of writing a compiler, but that too expects you to have significant
experience with GCC and the technology. If you are starting from scratch
and know little about compilers and processor architectures, you have a lot
to learn before you can succeed in such a port.

Also, a port to the Mac assumes a thorough familiarity with System-7, which
in itself is not easy, the internals of this system are complex.

After all, if it were easy to get a GCC port for the MAC, it would have
been done some time ago. Note that getting a GNAT port once a GCC port is
a MUCH simpler task, probably no more than a couple of person months at most
to get a first attempt.