Fixes #1231

common/space_lua/runtime.ts

@@ -18,7 +18,7 @@ export type JSValue = any;
 
 export interface ILuaFunction {
   call(sf: LuaStackFrame, ...args: LuaValue[]): Promise<LuaValue> | LuaValue;
-  toString(): string;
+  asString(): string;
 }
 
 export interface ILuaSettable {
@@ -196,10 +196,14 @@ export class LuaFunction implements ILuaFunction {
     return this.callWithArgs(resolvedArgs, env, sf);
   }
 
-  toString(): string {
+  asString(): string {
     return `<lua function(${this.body.parameters.join(", ")})>`;
   }
 
+  toString(): string {
+    return this.asString();
+  }
+
   private callWithArgs(
     args: LuaValue[],
     env: LuaEnv,
@@ -271,9 +275,13 @@ export class LuaNativeJSFunction implements ILuaFunction {
     }
   }
 
-  toString(): string {
+  asString(): string {
     return `<native js function: ${this.fn.name}>`;
   }
+
+  toString(): string {
+    return this.asString();
+  }
 }
 
 export class LuaBuiltinFunction implements ILuaFunction {
@@ -287,9 +295,13 @@ export class LuaBuiltinFunction implements ILuaFunction {
     return this.fn(sf, ...args);
   }
 
-  toString(): string {
+  asString(): string {
     return `<builtin lua function>`;
   }
+
+  toString(): string {
+    return this.asString();
+  }
 }
 
 export class LuaTable implements ILuaSettable, ILuaGettable {
@@ -730,6 +742,10 @@ export function luaToString(
     visited.add(value);
     return value.toStringAsync();
   }
+  if (value.asString) {
+    visited.add(value);
+    return value.asString();
+  }
   if (value instanceof LuaFunction) {
     // Don't recurse into the function body, just show the function signature
     return `<lua-function (${value.body.parameters.join(", ")})>`;

common/syscalls/lua.ts

@@ -2,8 +2,13 @@ import type { SysCallMapping } from "$lib/plugos/system.ts";
 import { evalExpression } from "$common/space_lua/eval.ts";
 import { parse, parseExpressionString } from "../space_lua/parse.ts";
 import type { CommonSystem } from "$common/common_system.ts";
-import { LuaStackFrame, luaValueToJS } from "$common/space_lua/runtime.ts";
+import {
+  LuaStackFrame,
+  luaToString,
+  luaValueToJS,
+} from "$common/space_lua/runtime.ts";
 import { buildThreadLocalEnv } from "$common/space_lua_api.ts";
+import { isSendable } from "$lib/plugos/util.ts";
 
 export function luaSyscalls(commonSystem: CommonSystem): SysCallMapping {
   return {
@@ -24,9 +29,17 @@ export function luaSyscalls(commonSystem: CommonSystem): SysCallMapping {
           commonSystem.spaceLuaEnv.env,
         );
         const sf = new LuaStackFrame(env, null);
-        return luaValueToJS(
-          evalExpression(ast, commonSystem.spaceLuaEnv.env, sf),
-        );
+        const result = evalExpression(ast, commonSystem.spaceLuaEnv.env, sf);
+        if (isSendable(result)) {
+          return luaValueToJS(result);
+        } else {
+          // This may evaluate to e.g. a function, which is not sendable, in this case we'll console.warn and return a stringified version of the result
+          console.warn(
+            "Lua eval result is not sendable, returning stringified version",
+            result,
+          );
+          return luaToString(result);
+        }
       } catch (e: any) {
         console.error("Lua eval error: ", e.message, e.sf?.astCtx);
         throw e;

lib/plugos/util.ts

@@ -0,0 +1,14 @@
+/**
+ * Checks if an object is sendable across the plugos worker boundary.
+ *
+ * @param o - The object to check.
+ * @returns `true` if the object is sendable, `false` otherwise.
+ */
+export function isSendable(o: any): boolean {
+  try {
+    structuredClone(o);
+    return true;
+  } catch {
+    return false;
+  }
+}

plugs/markdown/api.ts

@@ -105,10 +105,9 @@ export async function expandCodeWidgets(
         );
       }
     } else if (n.type === "LuaDirective") {
-      const expr: LuaExpression | null = findNodeOfType(
-        n,
-        "LuaExpressionDirective",
-      ) as LuaExpression | null;
+      const expr = findNodeOfType(n, "LuaExpressionDirective") as
+        | LuaExpression
+        | null;
       if (!expr) {
         return;
       }

web/cm_plugins/lua_widget.ts

@@ -25,8 +25,6 @@ export type LuaWidgetContent = {
   markdown?: string;
   // CSS classes for wrapper
   cssClasses?: string[];
-  // Index objects
-  objects?: ObjectValue<any>[];
   display?: "block" | "inline";
 } | string;