16 ms·

How would you provide incremental per-module compilation for your Nix derivation of the app?

toastal 4y ago
I don't know; that's why I'm asking. Maybe buildOpamPackage already does it? https://github.com/tweag/opam-nix#buildOpamProject https://github.com/tweag/opam-nix#buildOpamProject There's a buildDunePackage in the same region of the docs that runs `dune build` but that to me implies that dune is not needed(?). I haven't read too much into the project yet. The example (https://github.com/tweag/opam-nix/blob/4bb1a4c372f639f44fc6745f13c86f4397e82d34/examples/readme/my-package/my-package.opam https://github.com/tweag/opam-nix/blob/4bb1a4c372f639f44fc67...) would indicate that everything is configured from just the ${PROJECT}.opam file, but I don't have enough info on the toolchain to know if it's incremental per module or what... or if ocamlfind more complicated to work with than dune.
- ghostwriter 4y ago
  It does run `dune build`, but the unit of persistence within Nix is defined as `buildDunePackage`, i.e. the Nix store will only know about the package rather than individual modules and a change in a single module will cause a cascading rebuild of the entire package to update the nix store.
  - toastal 4y ago
    There are tools out there for other languages that _can_ handle incremental & per-modules builds, such as purs-nix for PureScript, so if opam-nix doesn't now, I'm sure it will in the future as a lot of projects are asking for this feature.
    - ghostwriter 4y ago
      > what does dune actually offer me if I’m using Nix to manage dependencies already? purs-nix is a good example that even if per-module compilation is made into derivations, the rest of the remaining heavy-lifting of constraints resolution is done by the external build tool. You can think of Nix as a dependency manager, but only with a huge caveat that it doesn't actually manage constraints that come with those dependencies, especially transitive ones.
      - toastal 4y ago
        That's a good read but I'm still unclear on dune vs. ocamlfind/ocamlopt. Is dune not using those under the covers like Nix could?

I don't know; that's why I'm asking. Maybe buildOpamPackage already does it? https://github.com/tweag/opam-nix#buildOpamProject https://github.com/tweag/opam-nix#buildOpamProject There's a buildDunePackage in the same region of the docs that runs `dune build` but that to me implies that dune is not needed(?). I haven't read too much into the project yet. The example (https://github.com/tweag/opam-nix/blob/4bb1a4c372f639f44fc6745f13c86f4397e82d34/examples/readme/my-package/my-package.opam https://github.com/tweag/opam-nix/blob/4bb1a4c372f639f44fc67...) would indicate that everything is configured from just the ${PROJECT}.opam file, but I don't have enough info on the toolchain to know if it's incremental per module or what... or if ocamlfind more complicated to work with than dune.

ghostwriter 4y ago
It does run `dune build`, but the unit of persistence within Nix is defined as `buildDunePackage`, i.e. the Nix store will only know about the package rather than individual modules and a change in a single module will cause a cascading rebuild of the entire package to update the nix store.
- toastal 4y ago
  There are tools out there for other languages that _can_ handle incremental & per-modules builds, such as purs-nix for PureScript, so if opam-nix doesn't now, I'm sure it will in the future as a lot of projects are asking for this feature.
  - ghostwriter 4y ago
    > what does dune actually offer me if I’m using Nix to manage dependencies already? purs-nix is a good example that even if per-module compilation is made into derivations, the rest of the remaining heavy-lifting of constraints resolution is done by the external build tool. You can think of Nix as a dependency manager, but only with a huge caveat that it doesn't actually manage constraints that come with those dependencies, especially transitive ones.
    - toastal 4y ago
      That's a good read but I'm still unclear on dune vs. ocamlfind/ocamlopt. Is dune not using those under the covers like Nix could?