Re: Updating plans of lang/ghc

[Alan Barrett <apb%cequrux.com@localhost>]

On Wed, 08 Jan 2014, David Holland wrote:
> The idea is that ghc-bootstrap depends on ghc (used for building) but
> ghc does *not* depend on ghc-bootstrap; instead once in a while
> someone takes the ghc-bootstrap package from the build host and posts
> it as a distfile in MASTER_SITE_LOCAL, and updates the distfile
> information in the main ghc package. I think this avoids most of the
> problems that otherwise come up.

Let's see if I understand this idea.

When you build ghc from pkgsrc, it downloads a binary blob from 
MASTER_SITE_LOCAL, and uses that as a compiler to build the 
current version of ghc from source code written in Haskell.

That binary blob is the result from somebody building 
ghc-bootstrap some time in the past, which then depended on ghc 
(possibly an older version), which depended on an older version of 
the binary blob.

That older version of the binary blob depends (indirectly) on 
an even older version of the binary blob, etc.  The number of 
steps in the chain are limited by uploading new versions of the 
binary blob as seldom as possible (essentially, only when the old 
bootstrap blob is not good enough to build a new compiler).

How was the very first version of the binary blob in 
MASTER_SITE_LOCAL built?  Is there a history traceable to a 
version that depended only on C code and a C compiler?

Will all the binary blobs, and the sources from which they were 
built, be saved ~forever, in case somebody wants to audit the 
provenance chain in the future?

Can ghc be built using some other Haskell implementation?

--apb (Alan Barrett)