refactor: small changes

overlays/builders.nix

@@ -2,7 +2,33 @@ _:
 
 final: _:
 with final.lib;
-{
+rec {
+  fishFile =
+    { name
+    , destination
+    , content
+    , checkPhase ? null
+    }:
+    final.writeTextFile {
+      inherit name destination;
+      executable = true;
+      allowSubstitutes = true;
+      preferLocalBuild = false;
+      text = ''
+        #!${getExe final.fish}
+
+        ${content}
+      '';
+
+      checkPhase =
+        if checkPhase == null then ''
+          runHook preCheck
+          ${getExe final.fish} -n "$target"
+          runHook postCheck
+        ''
+        else checkPhase;
+    };
+
   writeFishApplication =
     { name
     , text
@@ -11,30 +37,21 @@ with final.lib;
     , checkPhase ? null
     }:
     let
-      fishFile = destination: content: final.writeTextFile {
-        inherit name destination;
-        executable = true;
-        allowSubstitutes = true;
-        preferLocalBuild = false;
-        text = ''
-          #!${getExe final.fish}
+      runtimeHeader = optionalString (runtimeInputs != [ ])
+        ''export PATH="${makeBinPath runtimeInputs}:$PATH"'';
 
-          ${optionalString (runtimeInputs != [ ]) ''export PATH="${makeBinPath runtimeInputs}:$PATH"''}
-
-          ${content}
-        '';
-
-        checkPhase =
-          if checkPhase == null then ''
-            runHook preCheck
-            ${getExe final.fish} -n "$target"
-            runHook postCheck
-          ''
-          else checkPhase;
+      script = fishFile {
+        inherit checkPhase;
+        name = "${name}_script";
+        destination = "/bin/${name}";
+        content = concatLines [ runtimeHeader text ];
+      };
+      completions_file = fishFile {
+        inherit checkPhase;
+        name = "${name}_completions";
+        destination = "/share/fish/vendor_completions.d/${name}.fish";
+        content = concatLines [ runtimeHeader completions ];
       };
-
-      script = fishFile "/bin/${name}" text;
-      completions_file = fishFile "/share/fish/vendor_completions.d/${name}.fish" completions;
     in
     final.symlinkJoin {
       inherit name;