feat(build.nix): add man page for dhall & dhall-docs on MacOS

build.nix

@@ -1,6 +1,6 @@
 { pkgs, release }:
 
-{ simpleName, binNames, attrName }:
+{ simpleName, binNames, attrName, manPages ? [] }:
 
 let
   release = import ./release.nix;
@@ -46,6 +46,16 @@ pkgs.stdenv.mkDerivation rec {
 
     rmdir bin
 
+    ${pkgs.lib.optionalString (manPages != []) ''
+        ${pkgs.lib.concatMapStringsSep "\n" (manPage: ''
+          # TODO: split into $man output
+          manPagePath="$out/share/man/man1/${manPage}"
+          install -D -m644 -T "share/man/man1/${manPage}" "$manPagePath"
+          rm "share/man/man1/${manPage}"
+        '') manPages}
+        rmdir --parent share/man/man1
+     ''}
+
     # a bit hacky, but sourceRoot unfortunately unpacks to the runtime build dir
     rm env-vars .sandbox.sb || true
 

dhall-docs-simple.nix

@@ -4,4 +4,6 @@ import ./build.nix { inherit pkgs; release = import ./release.nix; } {
   simpleName = "dhall-docs-simple";
   binNames = [ "dhall-docs" ];
   attrName = "dhall-docs";
+  # see https://github.com/dhall-lang/dhall-haskell/issues/2104
+  manPages = if pkgs.stdenv.isDarwin then [ "dhall-docs.1" ] else [];
 }

dhall-simple.nix

@@ -4,4 +4,6 @@ import ./build.nix { inherit pkgs; release = import ./release.nix; } {
   simpleName = "dhall-simple";
   binNames = [ "dhall" ];
   attrName = "dhall";
+  # see https://github.com/dhall-lang/dhall-haskell/issues/2104
+  manPages = if pkgs.stdenv.isDarwin then [ "dhall.1" ] else [];
 }