Merge pull request #60406 from JohnAZoidberg/remove-isnull

treewide: Remove usage of isNull

35 files changed, 70 insertions, 76 deletions

diff --git a/nixos/modules/config/fonts/fontconfig-penultimate.nix b/nixos/modules/config/fonts/fontconfig-penultimate.nix
index 2c18244621af..04fa8b9559a9 100644
--- a/nixos/modules/config/fonts/fontconfig-penultimate.nix
+++ b/nixos/modules/config/fonts/fontconfig-penultimate.nix
@@ -31,7 +31,7 @@ let
   # use latest when no version is passed
   makeCacheConf = { version ? null }:
     let
-      fcPackage = if builtins.isNull version
+      fcPackage = if version == null
                   then "fontconfig"
                   else "fontconfig_${version}";
       makeCache = fontconfig: pkgs.makeFontsCache { inherit fontconfig; fontDirectories = config.fonts.fonts; };
diff --git a/nixos/modules/config/fonts/fontconfig.nix b/nixos/modules/config/fonts/fontconfig.nix
index d79c43c0b5b9..724158f73821 100644
--- a/nixos/modules/config/fonts/fontconfig.nix
+++ b/nixos/modules/config/fonts/fontconfig.nix
@@ -46,7 +46,7 @@ let cfg = config.fonts.fontconfig;
     # use latest when no version is passed
     makeCacheConf = { version ? null }:
       let
-        fcPackage = if builtins.isNull version
+        fcPackage = if version == null
                     then "fontconfig"
                     else "fontconfig_${version}";
         makeCache = fontconfig: pkgs.makeFontsCache { inherit fontconfig; fontDirectories = config.fonts.fonts; };
diff --git a/nixos/modules/config/sysctl.nix b/nixos/modules/config/sysctl.nix
index 74bff602a477..0c6a7e2431aa 100644
--- a/nixos/modules/config/sysctl.nix
+++ b/nixos/modules/config/sysctl.nix
@@ -8,7 +8,7 @@ let
     name = "sysctl option value";
     check = val:
       let
-        checkType = x: isBool x || isString x || isInt x || isNull x;
+        checkType = x: isBool x || isString x || isInt x || x == null;
       in
         checkType val || (val._type or "" == "override" && checkType val.content);
     merge = loc: defs: mergeOneOption loc (filterOverrides defs);
diff --git a/nixos/modules/installer/cd-dvd/iso-image.nix b/nixos/modules/installer/cd-dvd/iso-image.nix
index fd780be20825..d5c92cfc1d9e 100644
--- a/nixos/modules/installer/cd-dvd/iso-image.nix
+++ b/nixos/modules/installer/cd-dvd/iso-image.nix
@@ -198,7 +198,7 @@ let
     fi
 
     ${ # When there is a theme configured, use it, otherwise use the background image.
-    if (!isNull config.isoImage.grubTheme) then ''
+    if config.isoImage.grubTheme != null then ''
       # Sets theme.
       set theme=(hd0)/EFI/boot/grub-theme/theme.txt
       # Load theme fonts
@@ -622,7 +622,7 @@ in
         { source = "${pkgs.memtest86plus}/memtest.bin";
           target = "/boot/memtest.bin";
         }
-      ] ++ optionals (!isNull config.isoImage.grubTheme) [
+      ] ++ optionals (config.isoImage.grubTheme != null) [
         { source = config.isoImage.grubTheme;
           target = "/EFI/boot/grub-theme";
         }
diff --git a/nixos/modules/programs/bash/bash.nix b/nixos/modules/programs/bash/bash.nix
index 27b5f9e4b642..a7e57b8608d7 100644
--- a/nixos/modules/programs/bash/bash.nix
+++ b/nixos/modules/programs/bash/bash.nix
@@ -34,7 +34,7 @@ let
 
   bashAliases = concatStringsSep "\n" (
     mapAttrsFlatten (k: v: "alias ${k}=${escapeShellArg v}")
-      (filterAttrs (k: v: !isNull v) cfg.shellAliases)
+      (filterAttrs (k: v: v != null) cfg.shellAliases)
   );
 
 in
diff --git a/nixos/modules/programs/fish.nix b/nixos/modules/programs/fish.nix
index 622d2f96fe41..87f6816e4ac0 100644
--- a/nixos/modules/programs/fish.nix
+++ b/nixos/modules/programs/fish.nix
@@ -10,7 +10,7 @@ let
 
   fishAliases = concatStringsSep "\n" (
     mapAttrsFlatten (k: v: "alias ${k} ${escapeShellArg v}")
-      (filterAttrs (k: v: !isNull v) cfg.shellAliases)
+      (filterAttrs (k: v: v != null) cfg.shellAliases)
   );
 
 in
diff --git a/nixos/modules/programs/ssmtp.nix b/nixos/modules/programs/ssmtp.nix
index 44756171b74c..0e060e3f5226 100644
--- a/nixos/modules/programs/ssmtp.nix
+++ b/nixos/modules/programs/ssmtp.nix
@@ -148,7 +148,7 @@ in
         UseSTARTTLS=${yesNo cfg.useSTARTTLS}
         #Debug=YES
         ${optionalString (cfg.authUser != "")       "AuthUser=${cfg.authUser}"}
-        ${optionalString (!isNull cfg.authPassFile) "AuthPassFile=${cfg.authPassFile}"}
+        ${optionalString (cfg.authPassFile != null) "AuthPassFile=${cfg.authPassFile}"}
       '';
 
     environment.systemPackages = [pkgs.ssmtp];
diff --git a/nixos/modules/programs/zsh/zsh.nix b/nixos/modules/programs/zsh/zsh.nix
index b7117e5f90d7..bdb37eae23ef 100644
--- a/nixos/modules/programs/zsh/zsh.nix
+++ b/nixos/modules/programs/zsh/zsh.nix
@@ -12,7 +12,7 @@ let
 
   zshAliases = concatStringsSep "\n" (
     mapAttrsFlatten (k: v: "alias ${k}=${escapeShellArg v}")
-      (filterAttrs (k: v: !isNull v) cfg.shellAliases)
+      (filterAttrs (k: v: v != null) cfg.shellAliases)
   );
 
 in
diff --git a/nixos/modules/services/backup/znapzend.nix b/nixos/modules/services/backup/znapzend.nix
index 9c4c5545e35e..9c7f84655727 100644
--- a/nixos/modules/services/backup/znapzend.nix
+++ b/nixos/modules/services/backup/znapzend.nix
@@ -248,7 +248,7 @@ let
   cfg = config.services.znapzend;
 
   onOff = b: if b then "on" else "off";
-  nullOff = b: if isNull b then "off" else toString b;
+  nullOff = b: if b == null then "off" else toString b;
   stripSlashes = replaceStrings [ "/" ] [ "." ];
 
   attrsToFile = config: concatStringsSep "\n" (builtins.attrValues (
@@ -256,7 +256,7 @@ let
 
   mkDestAttrs = dst: with dst;
     mapAttrs' (n: v: nameValuePair "dst_${label}${n}" v) ({
-      "" = optionalString (! isNull host) "${host}:" + dataset;
+      "" = optionalString (host != null) "${host}:" + dataset;
       _plan = plan;
     } // optionalAttrs (presend != null) {
       _precmd = presend;
diff --git a/nixos/modules/services/cluster/kubernetes/kubelet.nix b/nixos/modules/services/cluster/kubernetes/kubelet.nix
index 2a4a0624555d..ccc8a16e788a 100644
--- a/nixos/modules/services/cluster/kubernetes/kubelet.nix
+++ b/nixos/modules/services/cluster/kubernetes/kubelet.nix
@@ -7,9 +7,9 @@ let
   cfg = top.kubelet;
 
   cniConfig =
-    if cfg.cni.config != [] && !(isNull cfg.cni.configDir) then
+    if cfg.cni.config != [] && cfg.cni.configDir != null then
       throw "Verbatim CNI-config and CNI configDir cannot both be set."
-    else if !(isNull cfg.cni.configDir) then
+    else if cfg.cni.configDir != null then
       cfg.cni.configDir
     else
       (pkgs.buildEnv {
@@ -373,7 +373,7 @@ in
       boot.kernelModules = ["br_netfilter"];
 
       services.kubernetes.kubelet.hostname = with config.networking;
-        mkDefault (hostName + optionalString (!isNull domain) ".${domain}");
+        mkDefault (hostName + optionalString (domain != null) ".${domain}");
 
       services.kubernetes.pki.certs = with top.lib; {
         kubelet = mkCert {
diff --git a/nixos/modules/services/cluster/kubernetes/pki.nix b/nixos/modules/services/cluster/kubernetes/pki.nix
index 32eacad9025f..e68660e8bdd4 100644
--- a/nixos/modules/services/cluster/kubernetes/pki.nix
+++ b/nixos/modules/services/cluster/kubernetes/pki.nix
@@ -285,7 +285,7 @@ in
         };
       };
 
-      environment.etc.${cfg.etcClusterAdminKubeconfig}.source = mkIf (!isNull cfg.etcClusterAdminKubeconfig)
+      environment.etc.${cfg.etcClusterAdminKubeconfig}.source = mkIf (cfg.etcClusterAdminKubeconfig != null)
         (top.lib.mkKubeConfig "cluster-admin" clusterAdminKubeconfig);
 
       environment.systemPackages = mkIf (top.kubelet.enable || top.proxy.enable) [
diff --git a/nixos/modules/services/continuous-integration/buildkite-agent.nix b/nixos/modules/services/continuous-integration/buildkite-agent.nix
index 2136778aff47..12cc3d2b1ccc 100644
--- a/nixos/modules/services/continuous-integration/buildkite-agent.nix
+++ b/nixos/modules/services/continuous-integration/buildkite-agent.nix
@@ -236,7 +236,7 @@ in
       };
 
     assertions = [
-      { assertion = cfg.hooksPath == hooksDir || all isNull (attrValues cfg.hooks);
+      { assertion = cfg.hooksPath == hooksDir || all (v: v == null) (attrValues cfg.hooks);
         message = ''
           Options `services.buildkite-agent.hooksPath' and
           `services.buildkite-agent.hooks.<name>' are mutually exclusive.
diff --git a/nixos/modules/services/continuous-integration/jenkins/default.nix b/nixos/modules/services/continuous-integration/jenkins/default.nix
index 1eca45fbd570..ec6a36413fe7 100644
--- a/nixos/modules/services/continuous-integration/jenkins/default.nix
+++ b/nixos/modules/services/continuous-integration/jenkins/default.nix
@@ -189,7 +189,7 @@ in {
 
       preStart =
         let replacePlugins =
-              if isNull cfg.plugins
+              if cfg.plugins == null
               then ""
               else
                 let pluginCmds = lib.attrsets.mapAttrsToList
diff --git a/nixos/modules/services/databases/cassandra.nix b/nixos/modules/services/databases/cassandra.nix
index d741ee48c48f..688938868020 100644
--- a/nixos/modules/services/databases/cassandra.nix
+++ b/nixos/modules/services/databases/cassandra.nix
@@ -22,11 +22,11 @@ let
              else {})
     );
   cassandraConfigWithAddresses = cassandraConfig //
-    ( if isNull cfg.listenAddress
+    ( if cfg.listenAddress == null
         then { listen_interface = cfg.listenInterface; }
         else { listen_address = cfg.listenAddress; }
     ) // (
-      if isNull cfg.rpcAddress
+      if cfg.rpcAddress == null
         then { rpc_interface = cfg.rpcInterface; }
         else { rpc_address = cfg.rpcAddress; }
     );
@@ -219,19 +219,13 @@ in {
   config = mkIf cfg.enable {
     assertions =
       [ { assertion =
-            ((isNull cfg.listenAddress)
-             || (isNull cfg.listenInterface)
-            ) && !((isNull cfg.listenAddress)
-                   && (isNull cfg.listenInterface)
-                  );
+          (cfg.listenAddress == null || cfg.listenInterface == null)
+          && !(cfg.listenAddress == null && cfg.listenInterface == null);
           message = "You have to set either listenAddress or listenInterface";
         }
         { assertion =
-            ((isNull cfg.rpcAddress)
-             || (isNull cfg.rpcInterface)
-            ) && !((isNull cfg.rpcAddress)
-                   && (isNull cfg.rpcInterface)
-                  );
+          (cfg.rpcAddress == null || cfg.rpcInterface == null)
+          && !(cfg.rpcAddress == null && cfg.rpcInterface == null);
           message = "You have to set either rpcAddress or rpcInterface";
         }
       ];
@@ -276,7 +270,7 @@ in {
           };
       };
     systemd.timers.cassandra-full-repair =
-      mkIf (!isNull cfg.fullRepairInterval) {
+      mkIf (cfg.fullRepairInterval != null) {
         description = "Schedule full repairs on Cassandra";
         wantedBy = [ "timers.target" ];
         timerConfig =
@@ -300,7 +294,7 @@ in {
           };
       };
     systemd.timers.cassandra-incremental-repair =
-      mkIf (!isNull cfg.incrementalRepairInterval) {
+      mkIf (cfg.incrementalRepairInterval != null) {
         description = "Schedule incremental repairs on Cassandra";
         wantedBy = [ "timers.target" ];
         timerConfig =
diff --git a/nixos/modules/services/databases/cockroachdb.nix b/nixos/modules/services/databases/cockroachdb.nix
index e977751b21ef..268fdcc819fd 100644
--- a/nixos/modules/services/databases/cockroachdb.nix
+++ b/nixos/modules/services/databases/cockroachdb.nix
@@ -7,7 +7,7 @@ let
   crdb = cfg.package;
 
   escape    = builtins.replaceStrings ["%"] ["%%"];
-  ifNotNull = v: s: optionalString (!isNull v) s;
+  ifNotNull = v: s: optionalString (v != null) s;
 
   startupCommand = lib.concatStringsSep " "
     [ # Basic startup
@@ -164,7 +164,7 @@ in
 
   config = mkIf config.services.cockroachdb.enable {
     assertions = [
-      { assertion = !cfg.insecure -> !(isNull cfg.certsDir);
+      { assertion = !cfg.insecure -> cfg.certsDir != null;
         message = "CockroachDB must have a set of SSL certificates (.certsDir), or run in Insecure Mode (.insecure = true)";
       }
     ];
diff --git a/nixos/modules/services/databases/pgmanage.nix b/nixos/modules/services/databases/pgmanage.nix
index 1a34c7f5ecee..1050c2dd481a 100644
--- a/nixos/modules/services/databases/pgmanage.nix
+++ b/nixos/modules/services/databases/pgmanage.nix
@@ -16,7 +16,7 @@ let
 
       super_only = ${builtins.toJSON cfg.superOnly}
 
-      ${optionalString (!isNull cfg.loginGroup) "login_group = ${cfg.loginGroup}"}
+      ${optionalString (cfg.loginGroup != null) "login_group = ${cfg.loginGroup}"}
 
       login_timeout = ${toString cfg.loginTimeout}
 
@@ -24,7 +24,7 @@ let
 
       sql_root = ${cfg.sqlRoot}
 
-      ${optionalString (!isNull cfg.tls) ''
+      ${optionalString (cfg.tls != null) ''
       tls_cert = ${cfg.tls.cert}
       tls_key = ${cfg.tls.key}
       ''}
diff --git a/nixos/modules/services/games/minecraft-server.nix b/nixos/modules/services/games/minecraft-server.nix
index 7d26d1501650..39a68f4b5536 100644
--- a/nixos/modules/services/games/minecraft-server.nix
+++ b/nixos/modules/services/games/minecraft-server.nix
@@ -215,8 +215,8 @@ in {
     networking.firewall = mkIf cfg.openFirewall (if cfg.declarative then {
       allowedUDPPorts = [ serverPort ];
       allowedTCPPorts = [ serverPort ]
-        ++ optional (! isNull queryPort) queryPort
-        ++ optional (! isNull rconPort) rconPort;
+        ++ optional (queryPort != null) queryPort
+        ++ optional (rconPort != null) rconPort;
     } else {
       allowedUDPPorts = [ defaultServerPort ];
       allowedTCPPorts = [ defaultServerPort ];
diff --git a/nixos/modules/services/logging/logcheck.nix b/nixos/modules/services/logging/logcheck.nix
index 9c64160e92bc..f139190a1709 100644
--- a/nixos/modules/services/logging/logcheck.nix
+++ b/nixos/modules/services/logging/logcheck.nix
@@ -227,7 +227,7 @@ in
     '';
 
     services.cron.systemCronJobs =
-        let withTime = name: {timeArgs, ...}: ! (builtins.isNull timeArgs);
+        let withTime = name: {timeArgs, ...}: timeArgs != null;
             mkCron = name: {user, cmdline, timeArgs, ...}: ''
               ${timeArgs} ${user} ${cmdline}
             '';
diff --git a/nixos/modules/services/mail/dovecot.nix b/nixos/modules/services/mail/dovecot.nix
index 30ad7d82fb80..139011dca23a 100644
--- a/nixos/modules/services/mail/dovecot.nix
+++ b/nixos/modules/services/mail/dovecot.nix
@@ -16,13 +16,13 @@ let
       sendmail_path = /run/wrappers/bin/sendmail
     ''
 
-    (if isNull cfg.sslServerCert then ''
+    (if cfg.sslServerCert == null then ''
       ssl = no
       disable_plaintext_auth = no
     '' else ''
       ssl_cert = <${cfg.sslServerCert}
       ssl_key = <${cfg.sslServerKey}
-      ${optionalString (!(isNull cfg.sslCACert)) ("ssl_ca = <" + cfg.sslCACert)}
+      ${optionalString (cfg.sslCACert != null) ("ssl_ca = <" + cfg.sslCACert)}
       ssl_dh = <${config.security.dhparams.params.dovecot2.path}
       disable_plaintext_auth = yes
     '')
@@ -298,7 +298,7 @@ in
   config = mkIf cfg.enable {
     security.pam.services.dovecot2 = mkIf cfg.enablePAM {};
 
-    security.dhparams = mkIf (! isNull cfg.sslServerCert) {
+    security.dhparams = mkIf (cfg.sslServerCert != null) {
       enable = true;
       params.dovecot2 = {};
     };
@@ -384,14 +384,14 @@ in
       { assertion = intersectLists cfg.protocols [ "pop3" "imap" ] != [];
         message = "dovecot needs at least one of the IMAP or POP3 listeners enabled";
       }
-      { assertion = isNull cfg.sslServerCert == isNull cfg.sslServerKey
-          && (!(isNull cfg.sslCACert) -> !(isNull cfg.sslServerCert || isNull cfg.sslServerKey));
+      { assertion = (cfg.sslServerCert == null) == (cfg.sslServerKey == null)
+          && (cfg.sslCACert != null -> !(cfg.sslServerCert == null || cfg.sslServerKey == null));
         message = "dovecot needs both sslServerCert and sslServerKey defined for working crypto";
       }
       { assertion = cfg.showPAMFailure -> cfg.enablePAM;
         message = "dovecot is configured with showPAMFailure while enablePAM is disabled";
       }
-      { assertion = (cfg.sieveScripts != {}) -> ((cfg.mailUser != null) && (cfg.mailGroup != null));
+      { assertion = cfg.sieveScripts != {} -> (cfg.mailUser != null && cfg.mailGroup != null);
         message = "dovecot requires mailUser and mailGroup to be set when sieveScripts is set";
       }
     ];
diff --git a/nixos/modules/services/misc/bepasty.nix b/nixos/modules/services/misc/bepasty.nix
index 006feca42b32..87d360681445 100644
--- a/nixos/modules/services/misc/bepasty.nix
+++ b/nixos/modules/services/misc/bepasty.nix
@@ -143,7 +143,7 @@ in
           serviceConfig = {
             Type = "simple";
             PrivateTmp = true;
-            ExecStartPre = assert !isNull server.secretKeyFile; pkgs.writeScript "bepasty-server.${name}-init" ''
+            ExecStartPre = assert server.secretKeyFile != null; pkgs.writeScript "bepasty-server.${name}-init" ''
               #!/bin/sh
               mkdir -p "${server.workDir}"
               mkdir -p "${server.dataDir}"
diff --git a/nixos/modules/services/misc/errbot.nix b/nixos/modules/services/misc/errbot.nix
index ac6ba2181de2..256adce2f02e 100644
--- a/nixos/modules/services/misc/errbot.nix
+++ b/nixos/modules/services/misc/errbot.nix
@@ -81,7 +81,7 @@ in {
 
     systemd.services = mapAttrs' (name: instanceCfg: nameValuePair "errbot-${name}" (
     let
-      dataDir = if !isNull instanceCfg.dataDir then instanceCfg.dataDir else
+      dataDir = if instanceCfg.dataDir != null then instanceCfg.dataDir else
         "/var/lib/errbot/${name}";
     in {
       after = [ "network-online.target" ];
diff --git a/nixos/modules/services/misc/taskserver/default.nix b/nixos/modules/services/misc/taskserver/default.nix
index 483bc99ad946..07dbee69db0c 100644
--- a/nixos/modules/services/misc/taskserver/default.nix
+++ b/nixos/modules/services/misc/taskserver/default.nix
@@ -48,7 +48,7 @@ let
     type = types.nullOr types.int;
     default = null;
     example = 365;
-    apply = val: if isNull val then -1 else val;
+    apply = val: if val == null then -1 else val;
     description = mkAutoDesc ''
       The expiration time of ${desc} in days or <literal>null</literal> for no
       expiration time.
@@ -82,7 +82,7 @@ let
          then attrByPath newPath (notFound newPath) cfg.pki.manual
          else findPkiDefinitions newPath val;
     in flatten (mapAttrsToList mkSublist attrs);
-  in all isNull (findPkiDefinitions [] manualPkiOptions);
+  in all (x: x == null) (findPkiDefinitions [] manualPkiOptions);
 
   orgOptions = { ... }: {
     options.users = mkOption {
diff --git a/nixos/modules/services/misc/zoneminder.nix b/nixos/modules/services/misc/zoneminder.nix
index 2bd2f3c7cc08..01720ba432ed 100644
--- a/nixos/modules/services/misc/zoneminder.nix
+++ b/nixos/modules/services/misc/zoneminder.nix
@@ -17,7 +17,7 @@ let
   defaultDir = "/var/lib/${user}";
   home = if useCustomDir then cfg.storageDir else defaultDir;
 
-  useCustomDir = !(builtins.isNull cfg.storageDir);
+  useCustomDir = cfg.storageDir != null;
 
   socket = "/run/phpfpm/${dirName}.sock";
 
diff --git a/nixos/modules/services/monitoring/graphite.nix b/nixos/modules/services/monitoring/graphite.nix
index 2365142af40e..d6473220c140 100644
--- a/nixos/modules/services/monitoring/graphite.nix
+++ b/nixos/modules/services/monitoring/graphite.nix
@@ -19,13 +19,13 @@ let
 
   graphiteLocalSettings = pkgs.writeText "graphite_local_settings.py" (
     "STATIC_ROOT = '${staticDir}'\n" +
-    optionalString (! isNull config.time.timeZone) "TIME_ZONE = '${config.time.timeZone}'\n"
+    optionalString (config.time.timeZone != null) "TIME_ZONE = '${config.time.timeZone}'\n"
     + cfg.web.extraConfig
   );
 
   graphiteApiConfig = pkgs.writeText "graphite-api.yaml" ''
     search_index: ${dataDir}/index
-    ${optionalString (!isNull config.time.timeZone) ''time_zone: ${config.time.timeZone}''}
+    ${optionalString (config.time.timeZone != null) ''time_zone: ${config.time.timeZone}''}
     ${optionalString (cfg.api.finders != []) ''finders:''}
     ${concatMapStringsSep "\n" (f: "  - " + f.moduleName) cfg.api.finders}
     ${optionalString (cfg.api.functions != []) ''functions:''}
diff --git a/nixos/modules/services/networking/flannel.nix b/nixos/modules/services/networking/flannel.nix
index c1f778ac139a..dd2f6454e954 100644
--- a/nixos/modules/services/networking/flannel.nix
+++ b/nixos/modules/services/networking/flannel.nix
@@ -92,7 +92,7 @@ in {
         Needed when running with Kubernetes as backend as this cannot be auto-detected";
       '';
       type = types.nullOr types.str;
-      default = with config.networking; (hostName + optionalString (!isNull domain) ".${domain}");
+      default = with config.networking; (hostName + optionalString (domain != null) ".${domain}");
       example = "node1.example.com";
     };
 
diff --git a/nixos/modules/services/networking/i2pd.nix b/nixos/modules/services/networking/i2pd.nix
index 40478b85b75e..f2be417738ee 100644
--- a/nixos/modules/services/networking/i2pd.nix
+++ b/nixos/modules/services/networking/i2pd.nix
@@ -12,9 +12,9 @@ let
   boolOpt = k: v: k + " = " + boolToString v;
   intOpt = k: v: k + " = " + toString v;
   lstOpt = k: xs: k + " = " + concatStringsSep "," xs;
-  optionalNullString = o: s: optional (! isNull s) (strOpt o s);
-  optionalNullBool = o: b: optional (! isNull b) (boolOpt o b);
-  optionalNullInt = o: i: optional (! isNull i) (intOpt o i);
+  optionalNullString = o: s: optional (s != null) (strOpt o s);
+  optionalNullBool = o: b: optional (b != null) (boolOpt o b);
+  optionalNullInt = o: i: optional (i != null) (intOpt o i);
   optionalEmptyList = o: l: optional ([] != l) (lstOpt o l);
 
   mkEnableTrueOption = name: mkEnableOption name // { default = true; };
@@ -225,7 +225,7 @@ let
   i2pdSh = pkgs.writeScriptBin "i2pd" ''
     #!/bin/sh
     exec ${pkgs.i2pd}/bin/i2pd \
-      ${if isNull cfg.address then "" else "--host="+cfg.address} \
+      ${if cfg.address == null then "" else "--host="+cfg.address} \
       --service \
       --conf=${i2pdConf} \
       --tunconf=${tunnelConf}
diff --git a/nixos/modules/services/networking/strongswan-swanctl/param-constructors.nix b/nixos/modules/services/networking/strongswan-swanctl/param-constructors.nix
index 5e74a96664f0..95a174122d04 100644
--- a/nixos/modules/services/networking/strongswan-swanctl/param-constructors.nix
+++ b/nixos/modules/services/networking/strongswan-swanctl/param-constructors.nix
@@ -56,7 +56,7 @@ rec {
   };
 
   documentDefault = description : strongswanDefault :
-    if isNull strongswanDefault
+    if strongswanDefault == null
     then description
     else description + ''
       </para><para>
diff --git a/nixos/modules/services/networking/strongswan-swanctl/param-lib.nix b/nixos/modules/services/networking/strongswan-swanctl/param-lib.nix
index fb87e81f3215..193ad27f035a 100644
--- a/nixos/modules/services/networking/strongswan-swanctl/param-lib.nix
+++ b/nixos/modules/services/networking/strongswan-swanctl/param-lib.nix
@@ -45,10 +45,10 @@ rec {
     filterEmptySets (
       (mapParamsRecursive (path: name: param:
         let value = attrByPath path null cfg;
-        in optionalAttrs (!isNull value) (param.render name value)
+        in optionalAttrs (value != null) (param.render name value)
       ) ps));
 
-  filterEmptySets = set : filterAttrs (n: v: !(isNull v)) (mapAttrs (name: value:
+  filterEmptySets = set : filterAttrs (n: v: (v != null)) (mapAttrs (name: value:
     if isAttrs value
     then let value' = filterEmptySets value;
          in if value' == {}
diff --git a/nixos/modules/services/search/kiba