lib/shell: add optional print functions

3 files changed, 7 insertions, 4 deletions

diff --git a/lib/mk-dev-shell.nix b/lib/mk-dev-shell.nix
index 4f46d69..fe2ac02 100644
--- a/lib/mk-dev-shell.nix
+++ b/lib/mk-dev-shell.nix
@@ -13,8 +13,8 @@ in pkgs.mkShell {
   shellHook = ''
     ${shellLib.exportEnvVars envVars}
 
-    ${pkgs.lib.optionalString (envVars != {}) (shellLib.printEnvVars envVars)}
-    ${pkgs.lib.optionalString (tools != []) (shellLib.printBins tools)}
+    ${shellLib.ifSomeAttrs envVars shellLib.printEnvVars}
+    ${shellLib.ifSomeList tools shellLib.printBins}
     echo
 
     ${if (shell != null) then shell else shellLib.startUserShell}
diff --git a/lib/mk-sandbox-system.nix b/lib/mk-sandbox-system.nix
index b678399..56ccad1 100644
--- a/lib/mk-sandbox-system.nix
+++ b/lib/mk-sandbox-system.nix
@@ -55,8 +55,8 @@ in rec {
       # TODO: also print a summary of the host mount points
       # TODO: also print a summary of the forwarded ports
       interactiveShellInit = lib.mkBefore ''
-        ${lib.optionalString (envVars != {}) (shellLib.printEnvVars envVars)}
-        ${lib.optionalString (tools != []) (shellLib.printBins tools)}
+        ${shellLib.ifSomeAttrs envVars shellLib.printEnvVars}
+        ${shellLib.ifSomeList tools shellLib.printBins}
         echo
       '';
     };
diff --git a/lib/shell.nix b/lib/shell.nix
index 3f6defc..d7d15fa 100644
--- a/lib/shell.nix
+++ b/lib/shell.nix
@@ -16,6 +16,9 @@ let
   };
 
 in rec {
+  ifSomeAttrs = attrs: f: pkgs.lib.optionalString (attrs != {}) (f attrs);
+  ifSomeList = list: f: pkgs.lib.optionalString (list != []) (f list);
+
   exportEnvVar = k: v: ''
     export ${escapeShellArg k}="${v}"
   '';