Introduce `mapNullable` into lib and use it in a few places

Also simply some configure flag logic my grep also alerted me too.

1 files changed, 4 insertions, 3 deletions

diff --git a/pkgs/servers/shishi/default.nix b/pkgs/servers/shishi/default.nix
index 3e340ba7df4..535571f46e2 100644
--- a/pkgs/servers/shishi/default.nix
+++ b/pkgs/servers/shishi/default.nix
@@ -6,9 +6,10 @@
 }:
 
 let
-  mkFlag = trueStr: falseStr: cond: name: val:
-    if cond == null then null else
-      "--${if cond != false then trueStr else falseStr}${name}${if val != null && cond != false then "=${val}" else ""}";
+  mkFlag = trueStr: falseStr: cond: name: val: "--"
+    + (if cond then trueStr else falseStr)
+    + name
+    + stdenv.lib.optionalString (val != null && cond != false) "=${val}";
   mkEnable = mkFlag "enable-" "disable-";
   mkWith = mkFlag "with-" "without-";
   mkOther = mkFlag "" "" true;