lib.generators.toLua: asBindings option

Allows to generate code block for setting of global variables

lib/generators.nix

@@ -434,6 +434,7 @@ ${expr "" v}
    Configuration:
      * multiline - by default is true which results in indented block-like view.
      * indent - initial indent.
+     * asBindings - by default generate single value, but with this use attrset to set global vars.
 
    Attention:
      Regardless of multiline parameter there is no trailing newline.
@@ -464,18 +465,35 @@ ${expr "" v}
     /* If this option is true, the output is indented with newlines for attribute sets and lists */
     multiline ? true,
     /* Initial indentation level */
-    indent ? ""
+    indent ? "",
+    /* Interpret as variable bindings */
+    asBindings ? false,
   }@args: v:
     with builtins;
     let
       innerIndent = "${indent}  ";
       introSpace = if multiline then "\n${innerIndent}" else " ";
       outroSpace = if multiline then "\n${indent}" else " ";
-      innerArgs = args // { indent = innerIndent; };
+      innerArgs = args // {
+        indent = if asBindings then indent else innerIndent;
+        asBindings = false;
+      };
       concatItems = concatStringsSep ",${introSpace}";
       isLuaInline = { _type ? null, ... }: _type == "lua-inline";
+
+      generatedBindings =
+          assert lib.assertMsg (badVarNames == []) "Bad Lua var names: ${toPretty {} badVarNames}";
+          libStr.concatStrings (
+            lib.attrsets.mapAttrsToList (key: value: "${indent}${key} = ${toLua innerArgs value}\n") v
+            );
+
+      # https://en.wikibooks.org/wiki/Lua_Programming/variable#Variable_names
+      matchVarName = match "[[:alpha:]_][[:alnum:]_]*(\\.[[:alpha:]_][[:alnum:]_]*)*";
+      badVarNames = filter (name: matchVarName name == null) (attrNames v);
     in
-    if v == null then
+    if asBindings then
+      generatedBindings
+    else if v == null then
       "nil"
     else if isInt v || isFloat v || isString v || isBool v then
       builtins.toJSON v

lib/tests/misc.nix

@@ -4,6 +4,11 @@
 with import ../default.nix;
 
 let
+  testingThrow = expr: {
+    expr = (builtins.tryEval (builtins.seq expr "didn't throw"));
+    expected = { success = false; value = false; };
+  };
+  testingDeepThrow = expr: testingThrow (builtins.deepSeq expr expr);
 
   testSanitizeDerivationName = { name, expected }:
   let
@@ -962,6 +967,41 @@ runTests {
     expected = ''{ 41, 43 }'';
   };
 
+  testToLuaEmptyBindings = {
+    expr = generators.toLua { asBindings = true; } {};
+    expected = "";
+  };
+
+  testToLuaBindings = {
+    expr = generators.toLua { asBindings = true; } { x1 = 41; _y = { a = 43; }; };
+    expected = ''
+      _y = {
+        ["a"] = 43
+      }
+      x1 = 41
+    '';
+  };
+
+  testToLuaPartialTableBindings = {
+    expr = generators.toLua { asBindings = true; } { "x.y" = 42; };
+    expected = ''
+      x.y = 42
+    '';
+  };
+
+  testToLuaIndentedBindings = {
+    expr = generators.toLua { asBindings = true; indent = "  "; } { x = { y = 42; }; };
+    expected = "  x = {\n    [\"y\"] = 42\n  }\n";
+  };
+
+  testToLuaBindingsWithSpace = testingThrow (
+    generators.toLua { asBindings = true; } { "with space" = 42; }
+  );
+
+  testToLuaBindingsWithLeadingDigit = testingThrow (
+    generators.toLua { asBindings = true; } { "11eleven" = 42; }
+  );
+
   testToLuaBasicExample = {
     expr = generators.toLua {} {
       cmd = [ "typescript-language-server" "--stdio" ];