treewide: use optionalString instead of 'then ""'

3 files changed, 5 insertions, 5 deletions

diff --git a/pkgs/development/libraries/ffmpeg/generic.nix b/pkgs/development/libraries/ffmpeg/generic.nix
index 12e59c939afe..4c31b82f3103 100644
--- a/pkgs/development/libraries/ffmpeg/generic.nix
+++ b/pkgs/development/libraries/ffmpeg/generic.nix
@@ -330,7 +330,7 @@ assert buildPostproc -> buildAvutil;
 assert buildSwscale -> buildAvutil;
 
 stdenv.mkDerivation (finalAttrs: {
-  pname = "ffmpeg" + (if ffmpegVariant == "small" then "" else "-${ffmpegVariant}");
+  pname = "ffmpeg" + (optionalString (ffmpegVariant != "small") "-${ffmpegVariant}");
   inherit version;
 
   src = fetchgit {
diff --git a/pkgs/development/libraries/opencv/tests.nix b/pkgs/development/libraries/opencv/tests.nix
index 03a89db0882f..d1966b1a4aa8 100644
--- a/pkgs/development/libraries/opencv/tests.nix
+++ b/pkgs/development/libraries/opencv/tests.nix
@@ -39,7 +39,7 @@ let
     "stitching"
     "video"
   ] ++ lib.optionals (!stdenv.isAarch64 && enableGStreamer) [ "gapi" ];
-  testRunner = if stdenv.isDarwin then "" else "${lib.getExe xvfb-run} -a ";
+  testRunner = lib.optionalString (!stdenv.isDarwin) "${lib.getExe xvfb-run} -a ";
   testsPreparation = ''
     touch $out
     # several tests want a write access, so we have to copy files
diff --git a/pkgs/development/libraries/qt-4.x/4.8/default.nix b/pkgs/development/libraries/qt-4.x/4.8/default.nix
index 68a300ac250d..a8257a36d39d 100644
--- a/pkgs/development/libraries/qt-4.x/4.8/default.nix
+++ b/pkgs/development/libraries/qt-4.x/4.8/default.nix
@@ -173,9 +173,9 @@ stdenv.mkDerivation rec {
     "-make" "libs" "-make" "tools" "-make" "translations"
     "-no-phonon" "-no-webkit" "-no-multimedia" "-audio-backend"
   ]) ++ [
-    "-${if demos then "" else "no"}make" "demos"
-    "-${if examples then "" else "no"}make" "examples"
-    "-${if docs then "" else "no"}make" "docs"
+    "-${lib.optionalString (!demos) "no"}make" "demos"
+    "-${lib.optionalString (!examples) "no"}make" "examples"
+    "-${lib.optionalString (!docs) "no"}make" "docs"
   ] ++ lib.optional developerBuild "-developer-build"
     ++ lib.optionals stdenv.hostPlatform.isDarwin [ platformFlag "unsupported/macx-clang-libc++" ]
     ++ lib.optionals stdenv.hostPlatform.isWindows [ platformFlag "win32-g++-4.6" ];