Re: How did you handle making a GNU/Linux distribution?

[Philip McGrath <philip@philipmcgrath.com>]

Hi Simon,

On 8/23/21 11:38 AM, zimoun wrote:
> The bootstrap path of Racket in Guix is not clear to me.  I miss if a
> Racket interpreter or compiler in its binary format is used (as
> Haskell for instance) or if all is compiled from source using tools
> already bootstrapped.  Anyway, I miss what you would like bootstrap?
> If you mean a trusted seed in order to start a package collection, you
> could use the current Guix binaires---as a starting point.

I wrote a long comment at the top of gnu/packages/racket.scm that 
explains the current state of affairs. (For anyone unfamiliar with the 
Guix source tree: 
<https://git.savannah.gnu.org/cgit/guix.git/tree/gnu/packages/racket.scm>)

In brief, Racket is bootstrapped from source using only a C 
compiler---including bootstrapping Racket's fork of Chez Scheme without 
an existing Chez Scheme compiler---with one exception: the "expander" 
subsystem (which implements the reader, module system, and macro 
expander) is implemented in Racket, and the older C implementation was 
completely replaced as of Racket 7.0. (One of the motivations was to fix 
many problems with the old implementation.) For bootstrapping, an 
intermediate representation as a "schemified" linklet is checked into 
the Racket source repository.

This impact is mitigated because, by design, the intermediate 
representation is "human-readable and -editable Scheme code". 
Anecdotally, when I read diffs of changes to the Racket repository, I 
sometimes read tens of lines of code before I realize that I'm looking 
at the generated version of the file, not the source. So the expander is 
not bootstrappable in the most rigorous sense, but it is readily auditable.

If someone wanted to tie the knot, the task would be to use an existing 
bootstappable language to write a minimal expander that can expand the 
canonical Racket implementation: if your output is identical to the 
checked-in generated files, you've succeeded. (Using Guile could avoid 
the heavy maintenance burden of the old C expander implementation, and 
indeed you could write just enough of an adapter to load the Racket 
source files into Guile, which is the technique Racket uses to bootstrap 
the Chez Scheme compiler.) I expect Racket would welcome a contribution 
along those lines; it just hasn't been a priority for anyone yet.

-Philip