Re: Porting GNAT to Debian Hurd

[Charles Hixson <charleshixson@earthling.net>]

Exposing my ignorance:
"B. Douglas Hilton" <doug.hilton@engineer.com> wrote in
news:3B2AE5F4.59E4ABE8@engineer.com: 

> I don't know if Hurd is ripe for a takeover, but it would
> probably not be excessively difficult to fork the
> development tree at this stage.
>     I was looking at the gnat sources, and it appears that
>     you need 
> to already have an older gnat installed to build a newer
> one. This might be tricky for Hurd, because I'd have to
> cross-compile gnat from Linux, then use it to do a native
> ...
> 
> - Doug
> 
> 
> ... 


When I first encountered Algol, I discovered that the basic 
specs were an Algol compiler that was written in a simple form 
of Algol.  This seemed quite strange, but I was told that it was 
reasonably simple to write a compiler for this stripped down 
Algol in assembler, so that really made it quite portable.

This seems to be the root of the problem here.  The underlying 
compiler for the language that GNAT is written in isn't some 
small stripped down subset.  It's Ada.  So you need a complete 
compiler to build a compiler.  I suppose that cross-
compilation's a simpler problem to solve.  What would really 
make things easier, though, would be an Ada compiler with an 
option to emit, say, C code.  Or Forth.  Or any of the other 
portable assemblers.  This might not be optimized for the target 
system, but it would almost always work.  One could think of it 
as a cross-compilation into a abstract machine.  

Speaking of abstract machines, does JGnat code require more than 
the JVM?  Perhaps the bootstrapping could be done via JGnat.  
Does the Hurd have a JVM?  Can Gnat be compiled into JVM code?  
(I think that C code would be a better choice, but JGnat already 
exists.  If it can compile everything into Java class files, 
then maybe the problem of getting started is partially solved.)

-- 
Charles Hixson

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