1 files changed, 28 insertions, 0 deletions
diff --git a/pkgs/build-support/fetchegg/default.nix b/pkgs/build-support/fetchegg/default.nix
new file mode 100644
index 00000000000..223d2098c77
--- /dev/null
+++ b/pkgs/build-support/fetchegg/default.nix
@@ -0,0 +1,28 @@
+# Fetches a chicken egg from henrietta using `chicken-install -r'
+# See: http://wiki.call-cc.org/chicken-projects/egg-index-4.html
+
+{ stdenv, chicken }:
+{ name, version, md5 ? "", sha256 ? "" }:
+
+stdenv.mkDerivation {
+  name = "chicken-${name}-export";
+  builder = ./builder.sh;
+  buildInputs = [ chicken ];
+
+  outputHashAlgo = if sha256 == "" then "md5" else "sha256";
+  outputHashMode = "recursive";
+  outputHash = if sha256 == "" then md5 else sha256;
+
+  inherit version;
+
+  eggName = name;
+
+  impureEnvVars = [
+    # We borrow these environment variables from the caller to allow
+    # easy proxy configuration.  This is impure, but a fixed-output
+    # derivation like fetchurl is allowed to do so since its result is
+    # by definition pure.
+    "http_proxy" "https_proxy" "ftp_proxy" "all_proxy" "no_proxy"
+  ];
+}
+