-*- mode: org; coding: utf-8; -*-

Copyright © 2012, 2013 Ludovic Courtès <ludo@gnu.org>

  Copying and distribution of this file, with or without modification,
  are permitted in any medium without royalty provided the copyright
  notice and this notice are preserved.

* integrate needed Nix code

Guix uses Nix’s daemon (‘nix-worker’, later renamed to ‘nix-daemon’) to
actually perform builds, scheduling, substitution of pre-built binaries,
and GC-related tasks.  The daemon mainly uses ‘libstore’ from Nix.
Integrating it in Guix itself will make Guix self-contained, thereby
simplifying our users’ lives.

** Remove dependency on OpenSSL

The ‘openssl’ command-line tool is used in libstore to sign store paths
to be exported, and to check such signatures.  The signing keys are
usually in /etc/nix/signing-key.{pub,sec}.  They are a PKCS#8-encoded
X.509 SubjectPublicKeyInfo.  These can be decoded with the [[http://lists.gnu.org/archive/html/help-gnutls/2012-12/msg00012.html][C API of
GnuTLS]], but not yet with its Guile bindings.  There’s also
‘gnutls_privkey_sign_data’ to sign, and related functions.

** Add a binary cache substituter

Like scripts/download-from-binary-cache.pl in Nix, but written in
Scheme.  Substituters allow pre-built binaries to be downloaded when
they are available from a trusted source.

** MAYBE Add a substituter that uses the GNUnet DHT

Would be neat if binaries could be pushed to and pulled from the GNUnet
DHT.  Guix users would sign their binaries, and define which binaries
they trust.

** Add a remote build hook

Like scripts/build-remote.pl in Nix.

* infrastructure

** have a Hydra instance build Guix packages

[[http://nixos.org/hydra/][Hydra]] is a continuous integration tool based on Nix.  It now has
[[https://github.com/NixOS/hydra/commit/f27ae1d5663680400cb99cfb898970f34d8d21be][Guile/Guix support]], which allows “build recipes” written in Guile using
Guix to be used directly on Hydra.

For a start, we may use the instance at hydra.nixos.org, generously
provided by TU Delft.  However, in the future, we may want to setup our
own instance at gnu.org.

* add guix pull

A tool that fetches the latest code from [[http://git.savannah.gnu.org/cgit/guix.git/snapshot/guix-master.tar.gz][cgit]], builds a derivation that
unpacks it, copies only .scm files (this excludes guix/config.in) and
compiles it, and then links to it from ~/.local/guix/latest .  Change
guix-build and guix-package to have that directory first in their load
path.

* user interface
** Add a package.el (Emacs) back-end

Unfortunately package.el is monolithic, so most likely we’d have to
write a new one based on it, as opposed to actually using it.

* extend <origin>
** add OpenPGP signatures:

   (origin
     (method http-fetch)
     (uri "http://.../foo.tgz")
     (signature-uri (string-append uri ".sig"))
     (signer-openpgp-fingerprint "..."))

** allow <origin> to be a derivation/package or a file

* extend <package>

** add support for ‘search-paths’

This should be passed to the build system, to extend package-specific
search path environment variables–like ‘GUILE_LOAD_PATH’, ‘PERL5LIB’,
etc.

** add a ‘user-environment-hook’

This should specify builder code to be run when building a user
environment with ‘guix-package’.  For instance, Texinfo’s hook would
create a new ‘dir’.

** add ‘patches’ there

** extend ‘propagated-build-inputs’ with support for multiple outputs

#+BEGIN_SRC scheme
  (outputs '("out" "include"))
  (propagated-build-inputs
    `(((("i1" ,p1 "o1")
        ("i2" ,p2))
       => "include")
      ("i3" ,p3)))
#+END_SRC

* synchronize package descriptions with the [[http://directory.fsf.org][FSD]] and/or the Womb

Meta-data for GNU packages, including descriptions and synopses, can be
dumped from the FSD:
http://directory.fsf.org/wiki?title=GNU/Export&action=purge .
We could periodically synchronize with that.

The [[./guix/gnu-maintenance.scm][Womb]] also contains synopses for all the GNU packages.

* support cross-compilation

Implement ‘package-cross-derivation’, and add the corresponding code in
‘gnu-build-system’.  Then, actually bootstrap a cross-compilation
environment–e.g., a cross-GNU environment.

* add a guildhall build system

The Guildhall is Guile’s packaging system.  It should be easy to add a
‘guildhall-build-system’ that does the right thing based on guildhall
recipes.

* gnu-build-system: produce a ‘debug’ derivation

Set a .gnu_debuglink in the main derivations to point to the sibling
file name (only the basename, to not retain a dependency on the ‘debug’
derivation.)

For /nix/store/xyz-foobar/bin/foo, we should have
/nix/store/abc-foobar-debug/lib/nix/store/xyz-foobar/bin/foo.debug (info
"(gdb) Separate Debug Files").

Users should have a default GDB setting with ~/.guix-profile/lib/debug
as their ‘debug-file-directory’.

* build-expression->derivation: define `%system' in the builder

Would allow build expressions to have system-dependent code, like
`glibc-dynamic-linker'.

* add ‘allowed-references’ in <package>

[[file:~/src/nix/src/libstore/build.cc::if%20(drv.env.find("allowedReferences")%20!%3D%20drv.env.end())%20{][See how Nix implements that internally]].

* union

Support sophisticated collision handling when building a union: check
whether the colliding files are identical, honor per-package priorities,
etc.

* guix package

** add ‘--list-generations’, and ‘--delete-generations’

* guix build utils
** Add equivalent to "rm -rf"
** Add equivalent to Nixpkgs's ‘wrapProgram’
** Change ‘patch-shebang’ to DTRT for /usr/bin/env

I.e., replace “#!/usr/bin/env perl” by “#!/nix/store/…/bin/perl”.
 
** MAYBE Change ‘ld-wrapper’ to add RPATH for libs passed by file name

** MAYBE Add equivalent to chrpath, possibly using [[https://gitorious.org/guile-dlhacks/guile-dlhacks/][guile-dlhacks]]

** MAYBE Add a hash-rewriting thing for deep dependency replacement without rebuild

See [[https://github.com/NixOS/nixpkgs/commit/d1662d715514e6ef9d3dc29f132f1b3d8e608a18][Shea Levy's `replace-dependency' in Nixpkgs]].

* distro
** choose a name! (Jinn?)
** port to new GNU/Linux platforms, notably ‘mipsel64-linux’
** port to GNU/Hurd, aka. ‘i686-gnu’

Problems include that current glibc releases do not build on GNU/Hurd.
In addition, there haven’t been stable releases of GNU Mach, MiG, and
Hurd, which would be a pre-condition.

** make a bootable GNU/Linux-Libre distro, with OS configuration EDSL

Similar in spirit to /etc/nixos/configuration.nix.
