treewide: use optionalString instead of 'then ""'

6 files changed, 17 insertions, 20 deletions

diff --git a/nixos/modules/services/networking/biboumi.nix b/nixos/modules/services/networking/biboumi.nix
index 1428856764e6..d44a46b35a29 100644
--- a/nixos/modules/services/networking/biboumi.nix
+++ b/nixos/modules/services/networking/biboumi.nix
@@ -8,8 +8,7 @@ let
   settingsFile = pkgs.writeText "biboumi.cfg" (
     generators.toKeyValue {
       mkKeyValue = k: v:
-        if v == null then ""
-        else generators.mkKeyValueDefault {} "=" k v;
+        lib.optionalString (v != null) (generators.mkKeyValueDefault {} "=" k v);
     } cfg.settings);
   need_CAP_NET_BIND_SERVICE = cfg.settings.identd_port != 0 && cfg.settings.identd_port < 1024;
 in
diff --git a/nixos/modules/services/networking/cjdns.nix b/nixos/modules/services/networking/cjdns.nix
index 5a19475161fd..80085da92702 100644
--- a/nixos/modules/services/networking/cjdns.nix
+++ b/nixos/modules/services/networking/cjdns.nix
@@ -239,7 +239,7 @@ in
       after = [ "network-online.target" ];
       bindsTo = [ "network-online.target" ];
 
-      preStart = if cfg.confFile != null then "" else ''
+      preStart = optionalString (cfg.confFile == null) ''
         [ -e /etc/cjdns.keys ] && source /etc/cjdns.keys
 
         if [ -z "$CJDNS_PRIVATE_KEY" ]; then
diff --git a/nixos/modules/services/networking/libreswan.nix b/nixos/modules/services/networking/libreswan.nix
index 785729d8f742..b8a3d6c8fdb5 100644
--- a/nixos/modules/services/networking/libreswan.nix
+++ b/nixos/modules/services/networking/libreswan.nix
@@ -14,8 +14,8 @@ let
     nonchars = filter (x : !(elem x.value chars))
                (imap0 (i: v: {ind = i; value = v;}) (stringToCharacters str));
   in
-    if length nonchars == 0 then ""
-    else substring (head nonchars).ind (add 1 (sub (last nonchars).ind (head nonchars).ind)) str;
+    lib.optionalString (length nonchars != 0)
+      (substring (head nonchars).ind (add 1 (sub (last nonchars).ind (head nonchars).ind)) str);
   indent = str: concatStrings (concatMap (s: ["  " (trim [" " "\t"] s) "\n"]) (splitString "\n" str));
   configText = indent (toString cfg.configSetup);
   connectionText = concatStrings (mapAttrsToList (n: v:
diff --git a/nixos/modules/services/networking/murmur.nix b/nixos/modules/services/networking/murmur.nix
index ebade7aa8e40..37a1ff8b2d34 100644
--- a/nixos/modules/services/networking/murmur.nix
+++ b/nixos/modules/services/networking/murmur.nix
@@ -19,8 +19,8 @@ let
     welcometext="${cfg.welcometext}"
     port=${toString cfg.port}
 
-    ${if cfg.hostName == "" then "" else "host="+cfg.hostName}
-    ${if cfg.password == "" then "" else "serverpassword="+cfg.password}
+    ${optionalString (cfg.hostName != "") "host=${cfg.hostName}"}
+    ${optionalString (cfg.password != "") "serverpassword=${cfg.password}"}
 
     bandwidth=${toString cfg.bandwidth}
     users=${toString cfg.users}
@@ -32,17 +32,17 @@ let
     bonjour=${boolToString cfg.bonjour}
     sendversion=${boolToString cfg.sendVersion}
 
-    ${if cfg.registerName     == "" then "" else "registerName="+cfg.registerName}
-    ${if cfg.registerPassword == "" then "" else "registerPassword="+cfg.registerPassword}
-    ${if cfg.registerUrl      == "" then "" else "registerUrl="+cfg.registerUrl}
-    ${if cfg.registerHostname == "" then "" else "registerHostname="+cfg.registerHostname}
+    ${optionalString (cfg.registerName != "") "registerName=${cfg.registerName}"}
+    ${optionalString (cfg.registerPassword == "") "registerPassword=${cfg.registerPassword}"}
+    ${optionalString (cfg.registerUrl != "") "registerUrl=${cfg.registerUrl}"}
+    ${optionalString (cfg.registerHostname != "") "registerHostname=${cfg.registerHostname}"}
 
     certrequired=${boolToString cfg.clientCertRequired}
-    ${if cfg.sslCert == "" then "" else "sslCert="+cfg.sslCert}
-    ${if cfg.sslKey  == "" then "" else "sslKey="+cfg.sslKey}
-    ${if cfg.sslCa   == "" then "" else "sslCA="+cfg.sslCa}
+    ${optionalString (cfg.sslCert != "") "sslCert=${cfg.sslCert}"}
+    ${optionalString (cfg.sslKey != "") "sslKey=${cfg.sslKey}"}
+    ${optionalString (cfg.sslCa != "") "sslCA=${cfg.sslCa}"}
 
-    ${lib.optionalString (cfg.dbus != null) "dbus=${cfg.dbus}"}
+    ${optionalString (cfg.dbus != null) "dbus=${cfg.dbus}"}
 
     ${cfg.extraConfig}
   '';
diff --git a/nixos/modules/services/networking/nsd.nix b/nixos/modules/services/networking/nsd.nix
index 09f3bdc7ae07..6db728e7aa5a 100644
--- a/nixos/modules/services/networking/nsd.nix
+++ b/nixos/modules/services/networking/nsd.nix
@@ -137,8 +137,8 @@ let
   '';
 
   yesOrNo = b: if b then "yes" else "no";
-  maybeString = prefix: x: if x == null then "" else ''${prefix} "${x}"'';
-  maybeToString = prefix: x: if x == null then "" else ''${prefix} ${toString x}'';
+  maybeString = prefix: x: optionalString (x != null) ''${prefix} "${x}"'';
+  maybeToString = prefix: x: optionalString (x != null) ''${prefix} ${toString x}'';
   forEach = pre: l: concatMapStrings (x: pre + x + "\n") l;
 
 
diff --git a/nixos/modules/services/networking/ssh/lshd.nix b/nixos/modules/services/networking/ssh/lshd.nix
index af64969c2fcd..129e42055514 100644
--- a/nixos/modules/services/networking/ssh/lshd.nix
+++ b/nixos/modules/services/networking/ssh/lshd.nix
@@ -165,9 +165,7 @@ in
         ${lsh}/sbin/lshd --daemonic \
           --password-helper="${lsh}/sbin/lsh-pam-checkpw" \
           -p ${toString portNumber} \
-          ${if interfaces == [] then ""
-            else (concatStrings (map (i: "--interface=\"${i}\"")
-                                     interfaces))} \
+          ${optionalString (interfaces != []) (concatStrings (map (i: "--interface=\"${i}\"") interfaces))} \
           -h "${hostKey}" \
           ${optionalString (!syslog) "--no-syslog" } \
           ${if passwordAuthentication then "--password" else "--no-password" } \