Fix example runner (langchain-ai#164)

* Fix example runner

* Improve example runner, add tsx for running without building first, add catch to promise returned by example

examples/package.json

@@ -10,7 +10,8 @@
   ],
   "scripts": {
     "build": "tsc --declaration --outDir dist/",
-    "start": "yarn build && node -r dotenv/config dist/index.js",
+    "start": "tsx -r dotenv/config src/index.ts",
+    "start:dist": "yarn build && node -r dotenv/config dist/index.js",
     "lint": "eslint src",
     "lint:fix": "yarn lint --fix",
     "format": "prettier --write \"**/*.ts\"",
@@ -41,6 +42,7 @@
     "eslint-plugin-import": "^2.27.5",
     "eslint-plugin-prettier": "^4.2.1",
     "prettier": "^2.8.3",
+    "tsx": "^3.12.3",
     "typescript": "^4.9.5"
   }
-}
+}

examples/src/README.md

@@ -0,0 +1,23 @@
+# langchain-examples
+
+This folder contains examples of how to use LangChain.
+
+## Run an example
+
+What you'll usually want to do.
+
+`yarn run start <path to example>`
+
+eg.
+
+`yarn run start ./src/prompts/few_shot.ts`
+
+## Run an example with the transpiled JS
+
+You shouldn't need to do this, but if you want to run an example with the transpiled JS, you can do so with:
+
+`yarn run start:dist <path to example>`
+
+eg.
+
+`yarn run start:dist ./dist/prompts/few_shot.js`

examples/src/index.ts

@@ -1,12 +1,40 @@
 import path from "path";
+import url from "url";
 
 const [exampleName, ...args] = process.argv.slice(2);
+
+// Allow people to pass all possible variations of a path to an example
+// ./src/foo.ts, ./dist/foo.js, src/foo.ts, dist/foo.js, foo.ts
+let exampleRelativePath: string;
+if (exampleName.startsWith("./src/")) {
+  exampleRelativePath = exampleName.slice(6);
+} else if (exampleName.startsWith("./dist/")) {
+  exampleRelativePath = exampleName.slice(7);
+} else if (exampleName.startsWith("src/")) {
+  exampleRelativePath = exampleName.slice(4);
+} else if (exampleName.startsWith("dist/")) {
+  exampleRelativePath = exampleName.slice(5);
+} else {
+  exampleRelativePath = exampleName;
+}
+
 let runExample;
 try {
-  // eslint-disable-next-line import/no-dynamic-require,global-require
-  ({ run: runExample } = require(path.join(__dirname, exampleName)));
+  ({ run: runExample } = await import(
+    path.join(
+      path.dirname(url.fileURLToPath(import.meta.url)),
+      exampleRelativePath
+    )
+  ));
 } catch (e) {
   throw new Error(`Could not load example ${exampleName}: ${e}`);
 }
 
-runExample(args);
+const maybePromise = runExample(args);
+
+if (maybePromise instanceof Promise) {
+  maybePromise.catch((e) => {
+    console.error(`Example failed with ${e}`);
+    process.exit(1);
+  });
+}

examples/tsconfig.json

@@ -6,6 +6,8 @@
       "ESNext",
       "DOM"
     ],
+    "target": "ES2020",
+    "module": "nodenext",
     "sourceMap": true,
     "allowSyntheticDefaultImports": true,
     "baseUrl": "./src",

langchain/.eslintrc.cjs

@@ -12,7 +12,7 @@ module.exports = {
     sourceType: "module",
   },
   plugins: ["@typescript-eslint"],
-  ignorePatterns: [".eslintrc.cjs", "node_modules"],
+  ignorePatterns: [".eslintrc.cjs", "create-entrypoints.js", "node_modules"],
   rules: {
     "@typescript-eslint/explicit-module-boundary-types": 0,
     "@typescript-eslint/no-empty-function": 0,

test-exports/tsconfig.json

@@ -6,6 +6,7 @@
       "ESNext",
       "DOM"
     ],
+    "module": "nodenext",
     "sourceMap": true,
     "allowSyntheticDefaultImports": true,
     "baseUrl": "./",