1 files changed, 88 insertions, 0 deletions
diff --git a/gleam/flake.nix b/gleam/flake.nix
new file mode 100644
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+++ b/gleam/flake.nix
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+{
+  description = "ocda-write: sample writers over the object-centric document abstraction, in Gleam";
+
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+
+  /* The library this is built on, as a source tree rather than a flake.
+     gleam.toml names it as the path dependency ./ocda-lib, which in a
+     working tree is a symlink to the library's gleam/ and is not carried
+     in git; the build is given the library from this input instead, and
+     nix-gleam puts it in place as a local package.
+
+     flake.lock pins the commit of the library this writer was built and
+     checked against. To build against a working copy of it instead:
+
+       nix build --override-input ocda-lib path:../../sisudoc-ocda-lib
+  */
+  inputs.ocda-lib = {
+    url = "git+git://git.sisudoc.org/tools/sisudoc-ocda-lib";
+    flake = false;
+  };
+
+  outputs = { self, nixpkgs, ocda-lib }:
+    let
+      system = "x86_64-linux"; # adjust for aarch64-linux / darwin
+      pkgs = import nixpkgs { inherit system; };
+
+      name = "ocda_write";
+
+      /* The builder, nix-gleam's, kept here in nix-gleam/ (see the README
+         there). It fetches each Hex dependency on its own, with the
+         checksum gleam has already written into manifest.toml, so there is
+         no hash in this file to keep up to date, and nothing a run of gleam
+         could make come out differently.
+      */
+      inherit (pkgs.callPackage ./nix-gleam { }) buildGleamApplication;
+
+      /* rebar3 with the port compiler already in it.
+
+         esqlite builds a NIF, and its rebar3 configuration asks for the
+         `pc` plugin, which rebar3 would otherwise fetch from Hex at build
+         time: impossible in a sandbox, and the build fails with
+         "missing_package pc". nixpkgs carries the plugin, so the answer is
+         a rebar3 that has it before it starts.
+      */
+      rebar3-pc = pkgs.beamPackages.rebar3WithPlugins {
+        plugins = [ pkgs.beamPackages.pc ];
+      };
+    in {
+      packages.${system} = {
+        default = self.packages.${system}.${name};
+
+        /* Shipped as an Erlang shipment rather than as an escript, because
+           sqlite on the BEAM is a NIF: esqlite compiles its own sqlite into
+           a shared object, and a NIF cannot be loaded from inside an
+           escript archive, the runtime needing a real file on disk. The
+           shipment keeps priv/ on disk, so it loads.
+        */
+        ${name} = buildGleamApplication {
+          pname = "ocda-write";
+          version = "2.0.0";
+          src = ./.;
+          localPackages = [ "${ocda-lib}/gleam" ];
+          rebar3Package = rebar3-pc;
+          nativeBuildInputs = [ pkgs.makeWrapper ];
+          preBuild = ''
+            export HOME=$TMPDIR
+          '';
+          installPhase = ''
+            runHook preInstall
+            mkdir -p $out/lib $out/bin
+            cp -r build/erlang-shipment $out/lib/${name}
+            makeWrapper $out/lib/${name}/entrypoint.sh $out/bin/ocda-write \
+              --add-flags run \
+              --prefix PATH : ${pkgs.lib.makeBinPath [ pkgs.beamPackages.erlang pkgs.coreutils ]}
+            runHook postInstall
+          '';
+          meta = {
+            description = "writes a document out from either serialisation of its abstraction";
+            mainProgram = "ocda-write";
+          };
+        };
+      };
+
+      devShells.${system}.default = pkgs.mkShell {
+        packages = [ pkgs.gleam pkgs.beamPackages.erlang pkgs.rebar3 pkgs.sqlite ];
+      };
+    };
+}