fetchdata and fetchmulti

pkgs/applications/audio/renoise/default.nix

@@ -1,36 +1,36 @@
-{ stdenv, lib, requireFile, demo, fetchurl, libX11, libXext, libXcursor, libXrandr, libjack2, alsaLib, ... }:
-
+{ stdenv, lib, fetchOneOf, demo
+, libX11, libXext, libXcursor, libXrandr, libjack2, alsaLib, ...
+}:
+let
+  demoStr = if demo then "-demo" else "";
+in
 stdenv.mkDerivation rec {
   name = "renoise";
 
   buildInputs = [ libX11 libXext libXcursor libXrandr alsaLib libjack2 ];
 
-  src =
-    if stdenv.system == "x86_64-linux" then
-        if demo then
-        fetchurl {
-            url = "http://files.renoise.com/demo/Renoise_3_0_1_Demo_x86_64.tar.bz2";
-            sha256 = "1q7f94wz2dbz659kpp53a3n1qyndsk0pkb29lxdff4pc3ddqwykg";
-        }
-        else
-        requireFile {
-            url = "http://backstage.renoise.com/frontend/app/index.html#/login";
-            name = "rns_3_0_1_linux_x86_64.tar.gz";
-            sha256 = "1yb5w5jrg9dk9fg5rfvfk6p0rxn4r4i32vxp2l9lzhbs02pv15wd";
-        }
-    else if stdenv.system == "i686-linux" then
-        if demo then
-        fetchurl {
-            url = "http://files.renoise.com/demo/Renoise_3_0_1_Demo_x86.tar.bz2";
-            sha256 = "0dgqvib4xh2yhgh2wajj11wsb6xiiwgfkhyz32g8vnyaij5q8f58";
-        }
-        else
-        requireFile {
-            url = "http://backstage.renoise.com/frontend/app/index.html#/login";
-            name = "rns_3_0_1_reg_x86.tar.gz";
-            sha256 = "1swax2jz0gswdpzz8alwjfd8rhigc2yfspj7p8wvdvylqrf7n8q7";
-        }
-    else throw "platform is not suppored by Renoise";
+  src = fetchOneOf "${stdenv.system}${demoStr}" {
+    "x86_64-linux-demo" = {
+      url = "http://files.renoise.com/demo/Renoise_3_0_1_Demo_x86_64.tar.bz2";
+      sha256 = "1q7f94wz2dbz659kpp53a3n1qyndsk0pkb29lxdff4pc3ddqwykg";
+    };
+    "x86_64-linux" = {
+      fetcher = "requireFile";
+      url = "http://backstage.renoise.com/frontend/app/index.html#/login";
+      name = "rns_3_0_1_linux_x86_64.tar.gz";
+      sha256 = "1yb5w5jrg9dk9fg5rfvfk6p0rxn4r4i32vxp2l9lzhbs02pv15wd";
+    };
+    "i686-linux-demo" = {
+      url = "http://files.renoise.com/demo/Renoise_3_0_1_Demo_x86.tar.bz2";
+      sha256 = "0dgqvib4xh2yhgh2wajj11wsb6xiiwgfkhyz32g8vnyaij5q8f58";
+    };
+    "i686-linux" = {
+      fetcher = "requireFile";
+      url = "http://backstage.renoise.com/frontend/app/index.html#/login";
+      name = "rns_3_0_1_reg_x86.tar.gz";
+      sha256 = "1swax2jz0gswdpzz8alwjfd8rhigc2yfspj7p8wvdvylqrf7n8q7";
+    };
+  };
 
   installPhase = ''
     cp -r Resources $out

pkgs/applications/editors/vscode/default.nix

@@ -1,32 +1,27 @@
-{ stdenv, lib, callPackage, fetchurl, unzip, atomEnv, makeDesktopItem,
-  makeWrapper, libXScrnSaver }:
+{ stdenv, lib, callPackage, fetchOneOf, unzip, atomEnv, makeDesktopItem }:
 
 let
   version = "1.6.1";
   rev = "9e4e44c19e393803e2b05fe2323cf4ed7e36880e";
-
-  sha256 = if stdenv.system == "i686-linux"    then "1aks84siflpjbd2s9y1f0vvvf3nas4f50cimjf25lijxzjxrlivy"
-      else if stdenv.system == "x86_64-linux"  then "05kbi081ih64fadj4k74grkk9ca3wga6ybwgs5ld0bal4ilw1q6i"
-      else if stdenv.system == "x86_64-darwin" then "00p2m8b0l3pkf5k74szw6kcql3j1fjnv3rwnhy24wfkg4b4ah2x9"
-      else throw "Unsupported system: ${stdenv.system}";
-
   urlBase = "https://az764295.vo.msecnd.net/stable/${rev}/";
-
-  urlStr = if stdenv.system == "i686-linux" then
-        urlBase + "code-stable-code_${version}-1476372351_i386.tar.gz"
-      else if stdenv.system == "x86_64-linux" then
-        urlBase + "code-stable-code_${version}-1476373175_amd64.tar.gz"
-      else if stdenv.system == "x86_64-darwin" then
-        urlBase + "VSCode-darwin-stable.zip"
-      else throw "Unsupported system: ${stdenv.system}";
 in
   stdenv.mkDerivation rec {
     name = "vscode-${version}";
     inherit version;
 
-    src = fetchurl {
-      url = urlStr;
-      inherit sha256;
+    src = fetchOneOf stdenv.system {
+      "i686-linux" = {
+        url = "${urlBase}/code-stable-code_${version}-1476372351_i386.tar.gz";
+        sha256 = "1aks84siflpjbd2s9y1f0vvvf3nas4f50cimjf25lijxzjxrlivy";
+      };
+      "x86_64-linux" = {
+        url = "${urlBase}/code-stable-code_${version}-1476373175_amd64.tar.gz";
+        sha256 = "05kbi081ih64fadj4k74grkk9ca3wga6ybwgs5ld0bal4ilw1q6i";
+      };
+      "x86_64-darwin" = {
+        url = "${urlBase}/VSCode-darwin-stable.zip";
+        sha256 = "00p2m8b0l3pkf5k74szw6kcql3j1fjnv3rwnhy24wfkg4b4ah2x9";
+      };
     };
 
     desktopItem = makeDesktopItem {

pkgs/build-support/fetchdata/default.nix

@@ -0,0 +1,46 @@
+{ fetchers }:
+
+# One fetcher to rule them all.
+#
+# The input should only be pure nix data, no function calls.
+#
+# Example usage:
+#
+#    fetchurl {
+#      url = "http://example.com/archive.tar.gz";
+#      sha256 = "...";
+#    };
+#
+# Becomes:
+#
+#    fetchdata {
+#      url = "http://example.com/archive.tar.gz";
+#      sha256 = "...";
+#    }
+#
+# If the data is not for fetchurl, it's possible to pass a "fetcher"
+# attribute:
+#
+#    fetchdata {
+#      fetcher = "fetchFromGitHub";
+#      repo    = "someone";
+#      repo    = "something";
+#      rev     = "v1.0";
+#      sha256  = "...";
+#    }
+#
+# Which means that the attributes can now be imported
+#
+#    fetchdata (import ./source.nix);
+#
+# That's the whole point of this function.
+#
+{ fetcher ? "fetchurl", ... }@attrs:
+  let
+    # TODO: add heuristic based on the input data instead
+    fetcher' =
+      fetchers."${fetcher}" or
+        (throw "fetcher of type `${fetcher}' not supported");
+    attrs' = builtins.removeAttrs attrs ["fetcher"];
+  in
+    fetcher' attrs'

pkgs/build-support/fetchdata/one-of.nix

@@ -0,0 +1,36 @@
+{ lib, fetchdata }:
+
+# Similar to fetchdata but allows to switch on an attribute
+#
+# Example usage:
+#
+#     fetchmulti stdenv.system {
+#        "x86_64-linux" = {
+#          url = "http://example.com/x86-linux.tar.gz";
+#          sha256 = "...";
+#        };
+#        "i686-linux" = {
+#          url = "http://example.com/i686-linux.tar.gz";
+#          sha256 = "...";
+#        };
+#     }
+#
+# All the urls are exposed on the `all' attribute which allows to run
+# `nix-fetchetch-url -A mypackage.src.all` to calculate the checksums of the:q
+#
+# FIXME: right now nix-prefetch-url only work if one of the keys match the
+#        current plaform
+#
+key: data:
+let
+  attrs = data."${key}" or (throw "`${key}' is not available as a source");
+
+  # A list of all the fetcher urls
+  urls = lib.foldl
+    (sum: v: ((fetchdata v).urls or []) ++ sum)
+    []
+    (builtins.attrValues data);
+in
+  (fetchdata attrs) // { all = { inherit urls; }; }
+
+

pkgs/development/compilers/openjdk/bootstrap.nix

@@ -1,35 +1,28 @@
-{ stdenv, runCommand, glibc, fetchurl, file
+{ stdenv, runCommand, glibc, fetchOneOf, file
 
 , version
 }:
 
 let
   # !!! These should be on nixos.org
-  src = if glibc.system == "x86_64-linux" then
-    (if version == "8" then
-      fetchurl {
-        url = "https://www.dropbox.com/s/a0lsq2ig4uguky5/openjdk8-bootstrap-x86_64-linux.tar.xz?dl=1";
-        sha256 = "18zqx6jhm3lizn9hh6ryyqc9dz3i96pwaz8f6nxfllk70qi5gvks";
-      }
-    else if version == "7" then
-      fetchurl {
-        url = "https://www.dropbox.com/s/rssfbeommrfbsjf/openjdk7-bootstrap-x86_64-linux.tar.xz?dl=1";
-        sha256 = "024gg2sgg4labxbc1nhn8lxls2p7d9h3b82hnsahwaja2pm1hbra";
-      }
-    else throw "No bootstrap for version")
-  else if glibc.system == "i686-linux" then
-    (if version == "8" then
-      fetchurl {
-        url = "https://www.dropbox.com/s/rneqjhlerijsw74/openjdk8-bootstrap-i686-linux.tar.xz?dl=1";
-        sha256 = "1yx04xh8bqz7amg12d13rw5vwa008rav59mxjw1b9s6ynkvfgqq9";
-      }
-    else if version == "7" then
-      fetchurl {
-        url = "https://www.dropbox.com/s/6xe64td7eg2wurs/openjdk7-bootstrap-i686-linux.tar.xz?dl=1";
-        sha256 = "0xwqjk1zx8akziw8q9sbjc1rs8s7c0w6mw67jdmmi26cwwp8ijnx";
-      }
-    else throw "No bootstrap for version")
-  else throw "No bootstrap for system";
+  src = fetchOneOf "${glibc.system}-jdk${version}" {
+    "x86_64-linux-jdk7" = {
+      url = "https://www.dropbox.com/s/rssfbeommrfbsjf/openjdk7-bootstrap-x86_64-linux.tar.xz?dl=1";
+      sha256 = "024gg2sgg4labxbc1nhn8lxls2p7d9h3b82hnsahwaja2pm1hbra";
+    };
+    "x86_64-linux-jdk8" = {
+      url = "https://www.dropbox.com/s/a0lsq2ig4uguky5/openjdk8-bootstrap-x86_64-linux.tar.xz?dl=1";
+      sha256 = "18zqx6jhm3lizn9hh6ryyqc9dz3i96pwaz8f6nxfllk70qi5gvks";
+    };
+    "i686-linux-jdk7" = {
+      url = "https://www.dropbox.com/s/6xe64td7eg2wurs/openjdk7-bootstrap-i686-linux.tar.xz?dl=1";
+      sha256 = "0xwqjk1zx8akziw8q9sbjc1rs8s7c0w6mw67jdmmi26cwwp8ijnx";
+    };
+    "i686-linux-jdk8" = {
+      url = "https://www.dropbox.com/s/rneqjhlerijsw74/openjdk8-bootstrap-i686-linux.tar.xz?dl=1";
+      sha256 = "1yx04xh8bqz7amg12d13rw5vwa008rav59mxjw1b9s6ynkvfgqq9";
+    };
+  };
 
   bootstrap = runCommand "openjdk-bootstrap" {
     passthru.home = "${bootstrap}/lib/openjdk";

pkgs/tools/typesetting/kindlegen/default.nix

@@ -1,34 +1,40 @@
-{ fetchurl, stdenv }:
+{ stdenv, fetchOneOf }:
 
 let
   version = "2.9";
   fileVersion = builtins.replaceStrings [ "." ] [ "_" ] version;
-
-  sha256 = {
-    "x86_64-linux"  = "15i20kzhdcmi94w7wfhqbl6j20v47cdakjm2mn3x8w495iddna4q";
-    "i686-linux"    = "15i20kzhdcmi94w7wfhqbl6j20v47cdakjm2mn3x8w495iddna4q";
-    "x86_64-darwin" = "0zniyn0s41fxqrajbgwxbcsj5vzf9m7a6yvdz2b11mphr00kpbbs";
-    "i686-darwin"   = "0zniyn0s41fxqrajbgwxbcsj5vzf9m7a6yvdz2b11mphr00kpbbs";
-    "x86_64-cygwin" = "02slfh1bbpijay4skj85cjiv7z43ha8vm5aa1lwiqjk86qbl1f3h";
-    "i686-cygwin"   = "02slfh1bbpijay4skj85cjiv7z43ha8vm5aa1lwiqjk86qbl1f3h";
-  }."${stdenv.system}" or (throw "system #{stdenv.system.} is not supported");
-
-  url = {
-    "x86_64-linux"  = "http://kindlegen.s3.amazonaws.com/kindlegen_linux_2.6_i386_v${fileVersion}.tar.gz";
-    "i686-linux"    = "http://kindlegen.s3.amazonaws.com/kindlegen_linux_2.6_i386_v${fileVersion}.tar.gz";
-    "x86_64-darwin" = "http://kindlegen.s3.amazonaws.com/KindleGen_Mac_i386_v${fileVersion}.zip";
-    "i686-darwin"   = "http://kindlegen.s3.amazonaws.com/KindleGen_Mac_i386_v${fileVersion}.zip";
-    "x86_64-cygwin" = "http://kindlegen.s3.amazonaws.com/kindlegen_win32_v${fileVersion}.zip";
-    "i686-cygwin"   = "http://kindlegen.s3.amazonaws.com/kindlegen_win32_v${fileVersion}.zip";
-  }."${stdenv.system}" or (throw "system #{stdenv.system.} is not supported");
+  baseURL = "http://kindlegen.s3.amazonaws.com";
+  src = fetchOneOf stdenv.system {
+    "x86_64-linux"  = {
+      url = "${baseURL}/kindlegen_linux_2.6_i386_v${fileVersion}.tar.gz";
+      sha256 = "15i20kzhdcmi94w7wfhqbl6j20v47cdakjm2mn3x8w495iddna4q";
+    };
+    "i686-linux"    = {
+      url = "${baseURL}/kindlegen_linux_2.6_i386_v${fileVersion}.tar.gz";
+      sha256 = "15i20kzhdcmi94w7wfhqbl6j20v47cdakjm2mn3x8w495iddna4q";
+    };
+    "x86_64-darwin" = {
+      url = "${baseURL}/KindleGen_Mac_i386_v${fileVersion}.zip";
+      sha256 = "0zniyn0s41fxqrajbgwxbcsj5vzf9m7a6yvdz2b11mphr00kpbbs";
+    };
+    "i686-darwin"   = {
+      url = "${baseURL}/KindleGen_Mac_i386_v${fileVersion}.zip";
+      sha256 = "0zniyn0s41fxqrajbgwxbcsj5vzf9m7a6yvdz2b11mphr00kpbbs";
+    };
+    "x86_64-cygwin" = {
+      url = "${baseURL}/kindlegen_win32_v${fileVersion}.zip";
+      sha256 = "02slfh1bbpijay4skj85cjiv7z43ha8vm5aa1lwiqjk86qbl1f3h";
+    };
+    "i686-cygwin"   = {
+      url = "${baseURL}/kindlegen_win32_v${fileVersion}.zip";
+      sha256 = "02slfh1bbpijay4skj85cjiv7z43ha8vm5aa1lwiqjk86qbl1f3h";
+    };
+  };
 
 in stdenv.mkDerivation rec {
   name = "kindlegen-${version}";
 
-  src = fetchurl {
-    inherit url;
-    inherit sha256;
-  };
+  inherit src;
 
   sourceRoot = ".";
 

pkgs/top-level/all-packages.nix

@@ -262,6 +262,13 @@ in
   } // removeAttrs args [ "repo" "rev" ]) // { inherit rev; };
 
   fetchNuGet = callPackage ../build-support/fetchnuget { };
+
+  fetchdata = callPackage ../build-support/fetchdata {
+    fetchers = pkgs;
+  };
+
+  fetchOneOf = callPackage ../build-support/fetchdata/one-of.nix { };
+
   buildDotnetPackage = callPackage ../build-support/build-dotnet-package { };
 
   resolveMirrorURLs = {url}: fetchurl {