[tgamblin]

FWIW this is what Spack does, and it uses a store layout like nix/guix. here are some chunks of the spack install tree path. All you really need is the hash, but we provide a bit more.

    $ spack find -p
    ...
    cmake@3.27.9             ~/spack/opt/spack/darwin-sonoma-m1/apple-clang-15.0.0/cmake-3.27.9-x6g5fl54kgt4nqmgnajrtfycivokap2p
    cmake@3.27.9             ~/spack/opt/spack/darwin-sonoma-m1/apple-clang-15.0.0/cmake-3.27.9-x4bznyafesvpdbplqhmnwwvy2zj5fdzs
    coreutils@9.3            ~/spack/opt/spack/darwin-sonoma-m1/apple-clang-15.0.0/coreutils-9.3-vlwyg7d3ysxfoom3erl6ai4yy7fuf2jn
    curl@8.4.0               ~/spack/opt/spack/darwin-sonoma-m1/apple-clang-15.0.0/curl-8.4.0-zjz6twa32vxnevika34kkrxjwo27z6vj
    curl@8.6.0               ~/spack/opt/spack/darwin-sonoma-m1/apple-clang-15.0.0/curl-8.6.0-da5tk7aqaqp6zdligjmahzwohzut65qc
    diffutils@3.9            ~/spack/opt/spack/darwin-sonoma-m1/apple-clang-15.0.0/diffutils-3.9-lau4vo7zlsktmbhyn3pf3x72nxhihsaq
    double-conversion@3.3.0  ~/spack/opt/spack/darwin-sonoma-m1/apple-clang-15.0.0/double-conversion-3.3.0-zihvj7vzedapjprk76awr7qied3k45n6
    emacs@29.2               ~/spack/opt/spack/darwin-sonoma-m1/apple-clang-15.0.0/emacs-29.2-x5v4wdhp4vfsuxquadackqckdvxrppwi
    expat@2.5.0              ~/spack/opt/spack/darwin-sonoma-m1/apple-clang-15.0.0/expat-2.5.0-hmdysf6hcrzuhcxu7fkecpvskzxecgps
    findutils@4.9.0          ~/spack/opt/spack/darwin-sonoma-m1/apple-clang-15.0.0/findutils-4.9.0-atynmdjhdjpb2ipurlk7cxtdep77m7mu
    fish@3.6.1               ~/spack/opt/spack/darwin-sonoma-m1/apple-clang-15.0.0/fish-3.6.1-sg3ws3rmbfgdfyhvjnhd5agepguj4yf2
    flex@2.6.3               ~/spack/opt/spack/darwin-sonoma-m1/apple-clang-15.0.0/flex-2.6.3-quw6ammnjxfutqtqcifvjfsp5nyqpeab
    freetype@2.11.1          ~/spack/opt/spack/darwin-sonoma-m1/apple-clang-15.0.0/freetype-2.11.1-ue2ofutkkawtzvcl47pqts4lasm5lgha
    gawk@5.2.2               ~/spack/opt/spack/darwin-sonoma-m1/apple-clang-15.0.0/gawk-5.2.2-jld7vb24rls64nbzkyxcp4alluyedfzv
    gdbm@1.23                ~/spack/opt/spack/darwin-sonoma-m1/apple-clang-15.0.0/gdbm-1.23-amtpuskagocirjhffgqrjas3bfbnzixi
    ...

You can also customize the install tree paths[1] with format strings; the default is:

    config:
      install_tree:
        root: $spack/opt/spack
        projections:
          all: "{architecture}/{compiler.name}-{compiler.version}/{name}-{version}-{hash}"

One reason `nix` uses `/nix/HASH` is because it results in shorter paths and avoids issues with long paths. We use sbang[2] to avoid the most common one -- that long shebangs don't work on some OS's (notably, most linux distros).

[1] https://spack.readthedocs.io/en/latest/config_yaml.html#conf...

[2] https://github.com/spack/sbang

[lproven]

Sounds fantastic!

Thanks for this -- I'll read up on it.