Add eslint rule to detect side effects (which prevent tree shaking), Add script that checks presence of side effects with rollup

langchain/.eslintrc.cjs

@@ -11,9 +11,34 @@ module.exports = {
     project: "./tsconfig.json",
     sourceType: "module",
   },
-  plugins: ["@typescript-eslint"],
-  ignorePatterns: [".eslintrc.cjs", "create-entrypoints.js", "node_modules"],
+  plugins: ["@typescript-eslint", "tree-shaking"],
+  ignorePatterns: [
+    ".eslintrc.cjs",
+    "create-entrypoints.js",
+    "check-tree-shaking.js",
+    "node_modules",
+  ],
   rules: {
+    "tree-shaking/no-side-effects-in-initialization": [
+      2,
+      {
+        noSideEffectsWhenCalled: [
+          {
+            module: "@jest/globals",
+            functions: [
+              "test",
+              "describe",
+              "it",
+              "beforeEach",
+              "afterEach",
+              "skip",
+              "each",
+              "only",
+            ],
+          },
+        ],
+      },
+    ],
     "@typescript-eslint/explicit-module-boundary-types": 0,
     "@typescript-eslint/no-empty-function": 0,
     "@typescript-eslint/no-shadow": 0,

langchain/check-tree-shaking.js

@@ -0,0 +1,78 @@
+import fs from "fs/promises";
+import { rollup } from "rollup";
+
+const packageJson = JSON.parse(await fs.readFile("package.json", "utf-8"));
+
+export function listEntrypoints() {
+  const exports = packageJson.exports;
+  const entrypoints = [];
+
+  for (const [key, value] of Object.entries(exports)) {
+    if (typeof value === "string") {
+      entrypoints.push(value);
+    } else if (typeof value === "object") {
+      entrypoints.push(value.import);
+    }
+  }
+
+  return entrypoints;
+}
+
+export function listExternals() {
+  return [
+    ...Object.keys(packageJson.dependencies),
+    ...Object.keys(packageJson.peerDependencies),
+    /node\:/,
+    "axios", // axios is a dependency of openai
+    "pdf-parse/lib/pdf-parse.js",
+  ];
+}
+
+export async function checkTreeShaking() {
+  const externals = listExternals();
+  const entrypoints = listEntrypoints();
+  const consoleLog = console.log;
+  const reportMap = new Map();
+
+  for (const entrypoint of entrypoints) {
+    let sideEffects = "";
+
+    console.log = function (...args) {
+      const line = args.length ? args.join(" ") : "";
+      if (line.trim().startsWith("First side effect in")) {
+        sideEffects += line + "\n";
+      }
+    };
+
+    await rollup({
+      external: externals,
+      input: entrypoint,
+      experimentalLogSideEffects: true,
+    });
+
+    reportMap.set(entrypoint, {
+      log: sideEffects,
+      hasSideEffects: sideEffects.length > 0,
+    });
+  }
+
+  console.log = consoleLog;
+
+  let failed = false;
+  for (const [entrypoint, report] of reportMap) {
+    if (report.hasSideEffects) {
+      failed = true;
+      console.log("---------------------------------");
+      console.log(`Tree shaking failed for ${entrypoint}`);
+      console.log(report.log);
+    }
+  }
+
+  if (failed) {
+    process.exit(1);
+  } else {
+    console.log("Tree shaking checks passed!");
+  }
+}
+
+checkTreeShaking();

langchain/package.json

@@ -49,7 +49,7 @@
     "url": "[email protected]:hwchase17/langchainjs.git"
   },
   "scripts": {
-    "build": "yarn clean && tsc --declaration --outDir dist/ && node create-entrypoints.js",
+    "build": "yarn clean && tsc --declaration --outDir dist/ && node create-entrypoints.js && node check-tree-shaking.js",
     "build:watch": "node create-entrypoints.js && tsc --declaration --outDir dist/ --watch",
     "lint": "eslint src && dpdm --exit-code circular:1 --no-warning --no-tree src/*.ts src/**/*.ts",
     "lint:fix": "yarn lint --fix",
@@ -92,6 +92,7 @@
     "eslint-config-prettier": "^8.6.0",
     "eslint-plugin-import": "^2.27.5",
     "eslint-plugin-prettier": "^4.2.1",
+    "eslint-plugin-tree-shaking": "^1.10.0",
     "hnswlib-node": "^1.4.2",
     "husky": "^8.0.3",
     "jest": "^29.5.0",
@@ -100,6 +101,7 @@
     "prettier": "^2.8.3",
     "puppeteer": "^19.7.2",
     "redis": "^4.6.4",
+    "rollup": "^3.19.1",
     "serpapi": "^1.1.1",
     "sqlite3": "^5.1.4",
     "srt-parser-2": "^1.2.2",

langchain/src/agents/agent.ts

@@ -20,31 +20,6 @@ class ParseError extends Error {
   }
 }
 
-// Hacky workaround to add static abstract methods. See detailed description of
-// issue here: https://stackoverflow.com/a/65847601
-export interface StaticAgent {
-  /**
-   * Create a prompt for this class
-   *
-   * @param tools - List of tools the agent will have access to, used to format the prompt.
-   * @param fields - Additional fields used to format the prompt.
-   *
-   * @returns A PromptTemplate assembled from the given tools and fields.
-   * */
-  // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  createPrompt(tools: Tool[], fields?: Record<string, any>): BasePromptTemplate;
-  /** Construct an agent from an LLM and a list of tools */
-  fromLLMAndTools(
-    llm: BaseLLM,
-    tools: Tool[],
-    // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    args?: Record<string, any>
-  ): Agent;
-  validateTools(_: Tool[]): void;
-}
-
-export const staticImplements = <T>(_: T) => {};
-
 /**
  * Class responsible for calling a language model and deciding an action.
  *
@@ -95,11 +70,36 @@ export abstract class Agent {
    */
   prepareForNewCall(): void {}
 
+  /**
+   * Create a prompt for this class
+   *
+   * @param tools - List of tools the agent will have access to, used to format the prompt.
+   * @param fields - Additional fields used to format the prompt.
+   *
+   * @returns A PromptTemplate assembled from the given tools and fields.
+   * */
+  static createPrompt(
+    _tools: Tool[],
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    _fields?: Record<string, any>
+  ): BasePromptTemplate {
+    throw new Error("Not implemented");
+  }
+
+  /** Construct an agent from an LLM and a list of tools */
+  static fromLLMAndTools(
+    _llm: BaseLLM,
+    _tools: Tool[],
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    _args?: Record<string, any>
+  ): Agent {
+    throw new Error("Not implemented");
+  }
+
   /**
    * Validate that appropriate tools are passed in
    */
-  // eslint-disable-next-line no-unused-vars
-  static validateTools(_: Tool[]): void {}
+  static validateTools(_tools: Tool[]): void {}
 
   _stop(): string[] {
     return [`\n${this.observationPrefix()}`];

langchain/src/agents/chat/index.ts

@@ -1,5 +1,5 @@
 import { LLMChain } from "../../chains/index.js";
-import { Agent, StaticAgent, staticImplements } from "../agent.js";
+import { Agent } from "../agent.js";
 import {
   SystemMessagePromptTemplate,
   HumanMessagePromptTemplate,
@@ -27,9 +27,7 @@ type ZeroShotAgentInput = AgentInput;
 /**
  * Agent for the MRKL chain.
  * @augments Agent
- * @augments StaticAgent
  */
-@(staticImplements<StaticAgent>)
 export class ChatAgent extends Agent {
   constructor(input: ZeroShotAgentInput) {
     super(input);

langchain/src/agents/chat_convo/index.ts

@@ -1,5 +1,5 @@
 import { LLMChain } from "../../chains/index.js";
-import { Agent, StaticAgent, staticImplements } from "../agent.js";
+import { Agent } from "../agent.js";
 import {
   SystemMessagePromptTemplate,
   HumanMessagePromptTemplate,
@@ -67,9 +67,7 @@ type ZeroShotAgentInput = AgentInput;
 /**
  * Agent for the MRKL chain.
  * @augments Agent
- * @augments StaticAgent
  */
-@(staticImplements<StaticAgent>)
 export class ChatConversationalAgent extends Agent {
   outputParser: BaseOutputParser;
 

langchain/src/agents/index.ts

@@ -5,7 +5,7 @@ export {
   SerializedZeroShotAgent,
   SerializedAgent,
 } from "./types.js";
-export { Agent, StaticAgent, staticImplements } from "./agent.js";
+export { Agent } from "./agent.js";
 export { AgentExecutor } from "./executor.js";
 export { ZeroShotAgent } from "./mrkl/index.js";
 export { ChatAgent } from "./chat/index.js";

langchain/src/agents/mrkl/index.ts

@@ -8,7 +8,7 @@ import {
   SerializedFromLLMAndTools,
   SerializedZeroShotAgent,
 } from "../types.js";
-import { Agent, StaticAgent, staticImplements } from "../agent.js";
+import { Agent } from "../agent.js";
 import { Tool } from "../tools/base.js";
 
 const FINAL_ANSWER_ACTION = "Final Answer:";
@@ -27,9 +27,7 @@ type ZeroShotAgentInput = AgentInput;
 /**
  * Agent for the MRKL chain.
  * @augments Agent
- * @augments StaticAgent
  */
-@(staticImplements<StaticAgent>)
 export class ZeroShotAgent extends Agent {
   constructor(input: ZeroShotAgentInput) {
     super(input);

langchain/src/cache.ts

@@ -20,22 +20,26 @@ export abstract class BaseCache<T = Generation[]> {
   abstract update(prompt: string, llmKey: string, value: T): Promise<void>;
 }
 
+const GLOBAL_MAP = new Map();
+
 export class InMemoryCache<T = Generation[]> extends BaseCache<T> {
-  #cache: Map<string, T>;
+  private cache: Map<string, T>;
 
-  constructor() {
+  constructor(map?: Map<string, T>) {
     super();
-    this.#cache = new Map();
+    this.cache = map ?? new Map();
   }
 
   lookup(prompt: string, llmKey: string): Promise<T | null> {
-    return Promise.resolve(
-      this.#cache.get(getCacheKey(prompt, llmKey)) ?? null
-    );
+    return Promise.resolve(this.cache.get(getCacheKey(prompt, llmKey)) ?? null);
   }
 
   async update(prompt: string, llmKey: string, value: T): Promise<void> {
-    this.#cache.set(getCacheKey(prompt, llmKey), value);
+    this.cache.set(getCacheKey(prompt, llmKey), value);
+  }
+
+  static global(): InMemoryCache {
+    return new InMemoryCache(GLOBAL_MAP);
   }
 }
 
@@ -44,11 +48,11 @@ export class InMemoryCache<T = Generation[]> extends BaseCache<T> {
  * TODO: Generalize to support other types.
  */
 export class RedisCache extends BaseCache<Generation[]> {
-  #redisClient: RedisClientType;
+  private redisClient: RedisClientType;
 
   constructor(redisClient: RedisClientType) {
     super();
-    this.#redisClient = redisClient;
+    this.redisClient = redisClient;
   }
 
   public async lookup(
@@ -57,7 +61,7 @@ export class RedisCache extends BaseCache<Generation[]> {
   ): Promise<Generation[] | null> {
     let idx = 0;
     let key = getCacheKey(prompt, llmKey, String(idx));
-    let value = await this.#redisClient.get(key);
+    let value = await this.redisClient.get(key);
     const generations: Generation[] = [];
 
     while (value) {
@@ -68,7 +72,7 @@ export class RedisCache extends BaseCache<Generation[]> {
       generations.push({ text: value });
       idx += 1;
       key = getCacheKey(prompt, llmKey, String(idx));
-      value = await this.#redisClient.get(key);
+      value = await this.redisClient.get(key);
     }
 
     return generations.length > 0 ? generations : null;
@@ -81,7 +85,7 @@ export class RedisCache extends BaseCache<Generation[]> {
   ): Promise<void> {
     for (let i = 0; i < value.length; i += 1) {
       const key = getCacheKey(prompt, llmKey, String(i));
-      await this.#redisClient.set(key, value[i].text);
+      await this.redisClient.set(key, value[i].text);
     }
   }
 }

langchain/src/callbacks/tests/tracer.test.ts

@@ -11,6 +11,7 @@ import {
 const TEST_SESSION_ID = 2023;
 const _DATE = 1620000000000;
 
+// eslint-disable-next-line tree-shaking/no-side-effects-in-initialization
 Date.now = jest.fn(() => _DATE);
 
 class FakeTracer extends BaseTracer {

langchain/src/chains/chat_vector_db_chain.ts

@@ -182,7 +182,6 @@ export class ChatVectorDBQAChain
     const question_generator_prompt = PromptTemplate.fromTemplate(
       questionGeneratorTemplate || question_generator_template
     );
-
     const qa_prompt = PromptTemplate.fromTemplate(qaTemplate || qa_template);
 
     const qaChain = loadQAStuffChain(llm, { prompt: qa_prompt });

langchain/src/chains/conversation.ts

@@ -11,11 +11,6 @@ Current conversation:
 Human: {input}
 AI:`;
 
-const defaultPrompt = new PromptTemplate({
-  template: defaultTemplate,
-  inputVariables: ["history", "input"],
-});
-
 export class ConversationChain extends LLMChain {
   constructor(fields: {
     llm: BaseLanguageModel;
@@ -24,7 +19,12 @@ export class ConversationChain extends LLMChain {
     memory?: BaseMemory;
   }) {
     super({
-      prompt: fields.prompt ?? defaultPrompt,
+      prompt:
+        fields.prompt ??
+        new PromptTemplate({
+          template: defaultTemplate,
+          inputVariables: ["history", "input"],
+        }),
       llm: fields.llm,
       outputKey: fields.outputKey ?? "response",
     });