Nixpkgs support for dhall-to-nixpkgs

The motivation for this change is to enable a new Dhall command-line utility called `dhall-to-nixpkgs` which converts Dhall packages to buildable Nix packages. You can think of `dhall-to-nixpkgs` as the Dhall analog of `cabal2nix`. You can find the matching pull request for `dhall-to-nixpkgs` here: https://github.com/dhall-lang/dhall-haskell/pull/1826 The two main changes required to support `dhall-to-nixpkgs` are: * Two new `buildDhall{Directory,GitHub}Package` utilities are added `dhall-to-nixpkgs` uses these in the generated output * `pkgs.dhallPackages` now selects a default version for each package using the `prefer` utility All other versions are still buildable via a `passthru` attribute
2020-06-17 15:57:21 +02:00
parent 2ee84ca8e2
commit 459cf94991
6 changed files with 130 additions and 72 deletions
@@ -0,0 +1,50 @@
+{ buildDhallPackage, fetchFromGitHub, lib }:
+
+# This function is used by `dhall-to-nixpkgs` when given a GitHub repository
+lib.makeOverridable
+  ( { # Arguments passed through to `buildDhallPackage`
+      name
+    , dependencies ? []
+    , source ? false
+
+    , # The directory containing the Dhall files, if other than the root of the
+      # repository
+      directory ? ""
+    , # The file to import, relative to the above directory
+      file ? "package.dhall"
+
+      # Arguments passed through to `fetchFromGitHub`
+    , owner
+    , repo
+    , rev
+      # Extra arguments passed through to `fetchFromGitHub`, such as the hash
+      # or `fetchSubmodules`
+    , ...
+    }@args:
+
+    buildDhallPackage {
+      inherit name dependencies source;
+
+      code =
+        let
+          src = fetchFromGitHub ({
+            name = "${name}-source";
+
+            inherit owner repo rev;
+          } // removeAttrs args [
+            "name"
+            "dependencies"
+            "source"
+            "directory"
+            "file"
+            "owner"
+            "repo"
+            "rev"
+          ]);
+
+          prefix = lib.optionalString (directory != "") "${directory}/";
+
+        in
+          "${src}/${prefix}${file}";
+    }
+  )