all[patch]: Fix typing across different core versions by using interfaces instead of abstract classes

docs/core_docs/docs/modules/chains/popular/chat_vector_db_legacy.mdx

@@ -24,11 +24,11 @@ In the above code snippet, the fromLLM method of the `ConversationalRetrievalQAC
 
 ```typescript
 static fromLLM(
-  llm: BaseLanguageModel,
-  retriever: BaseRetriever,
+  llm: BaseLanguageModelInterface,
+  retriever: BaseRetrieverInterface,
   options?: {
     questionGeneratorChainOptions?: {
-      llm?: BaseLanguageModel;
+      llm?: BaseLanguageModelInterface;
       template?: string;
     };
     qaChainOptions?: QAChainParams;

docs/core_docs/docs/modules/data_connection/vectorstores/index.mdx

@@ -109,13 +109,13 @@ abstract class BaseVectorStore implements VectorStore {
   static fromTexts(
     texts: string[],
     metadatas: object[] | object,
-    embeddings: Embeddings,
+    embeddings: EmbeddingsInterface,
     dbConfig: Record<string, any>
   ): Promise<VectorStore>;
 
   static fromDocuments(
     docs: Document[],
-    embeddings: Embeddings,
+    embeddings: EmbeddingsInterface,
     dbConfig: Record<string, any>
   ): Promise<VectorStore>;
 }

docs/core_docs/docs/modules/model_io/prompts/prompt_selectors/index.mdx

@@ -11,7 +11,7 @@ The interface for prompt selectors is quite simple:
 
 ```typescript
 abstract class BasePromptSelector {
-  abstract getPrompt(llm: BaseLanguageModel): BasePromptTemplate;
+  abstract getPrompt(llm: BaseLanguageModelInterface): BasePromptTemplate;
 }
 ```
 
@@ -31,7 +31,7 @@ The example below shows how to use a prompt selector when loading a chain:
 
 ```typescript
 const loadQAStuffChain = (
-  llm: BaseLanguageModel,
+  llm: BaseLanguageModelInterface,
   params: StuffQAChainParams = {}
 ) => {
   const { prompt = QA_PROMPT_SELECTOR.getPrompt(llm) } = params;

examples/src/chains/advanced_subclass_call.ts

@@ -1,16 +1,16 @@
 import { BasePromptTemplate, PromptTemplate } from "langchain/prompts";
-import { BaseLanguageModel } from "langchain/base_language";
+import type { BaseLanguageModelInterface } from "@langchain/core/language_models/base";
 import { CallbackManagerForChainRun } from "langchain/callbacks";
 import { BaseChain, ChainInputs } from "langchain/chains";
 import { ChainValues } from "langchain/schema";
 
 export interface MyCustomChainInputs extends ChainInputs {
-  llm: BaseLanguageModel;
+  llm: BaseLanguageModelInterface;
   promptTemplate: string;
 }
 
 export class MyCustomChain extends BaseChain implements MyCustomChainInputs {
-  llm: BaseLanguageModel;
+  llm: BaseLanguageModelInterface;
 
   promptTemplate: string;
 

langchain-core/src/callbacks/base.ts

@@ -14,7 +14,7 @@ import {
   get_lc_unique_name,
 } from "../load/serializable.js";
 import type { SerializedFields } from "../load/map_keys.js";
-import { Document } from "../documents/document.js";
+import type { DocumentInterface } from "../documents/document.js";
 
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 type Error = any;
@@ -242,7 +242,7 @@ abstract class BaseCallbackHandlerMethodsClass {
   Promise<any> | any;
 
   handleRetrieverEnd?(
-    documents: Document[],
+    documents: DocumentInterface[],
     runId: string,
     parentRunId?: string,
     tags?: string[]

langchain-core/src/callbacks/manager.ts

@@ -21,7 +21,7 @@ import {
 } from "../tracers/tracer_langchain.js";
 import { consumeCallback } from "./promises.js";
 import { Serialized } from "../load/serializable.js";
-import { Document } from "../documents/document.js";
+import type { DocumentInterface } from "../documents/document.js";
 
 type BaseCallbackManagerMethods = {
   [K in keyof CallbackHandlerMethods]?: (
@@ -153,7 +153,7 @@ export class CallbackManagerForRetrieverRun
     return manager;
   }
 
-  async handleRetrieverEnd(documents: Document[]): Promise<void> {
+  async handleRetrieverEnd(documents: DocumentInterface[]): Promise<void> {
     await Promise.all(
       this.handlers.map((handler) =>
         consumeCallback(async () => {

langchain-core/src/documents/document.ts

@@ -7,13 +7,22 @@ export interface DocumentInput<
   metadata?: Metadata;
 }
 
+export interface DocumentInterface<
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  Metadata extends Record<string, any> = Record<string, any>
+> {
+  pageContent: string;
+
+  metadata: Metadata;
+}
+
 /**
  * Interface for interacting with a document.
  */
 export class Document<
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   Metadata extends Record<string, any> = Record<string, any>
-> implements DocumentInput
+> implements DocumentInput, DocumentInterface
 {
   pageContent: string;
 

langchain-core/src/documents/transformers.ts

@@ -1,6 +1,6 @@
 import { Runnable } from "../runnables/base.js";
 import type { BaseCallbackConfig } from "../callbacks/manager.js";
-import type { Document } from "./document.js";
+import type { DocumentInterface } from "./document.js";
 
 /**
  * Abstract base class for document transformation systems.
@@ -13,8 +13,8 @@ import type { Document } from "./document.js";
  * many smaller documents.
  */
 export abstract class BaseDocumentTransformer<
-  RunInput extends Document[] = Document[],
-  RunOutput extends Document[] = Document[]
+  RunInput extends DocumentInterface[] = DocumentInterface[],
+  RunOutput extends DocumentInterface[] = DocumentInterface[]
 > extends Runnable<RunInput, RunOutput> {
   lc_namespace = ["langchain_core", "documents", "transformers"];
 
@@ -42,7 +42,9 @@ export abstract class BaseDocumentTransformer<
  * for each input document.
  */
 export abstract class MappingDocumentTransformer extends BaseDocumentTransformer {
-  async transformDocuments(documents: Document[]): Promise<Document[]> {
+  async transformDocuments(
+    documents: DocumentInterface[]
+  ): Promise<DocumentInterface[]> {
     const newDocuments = [];
     for (const document of documents) {
       const transformedDocument = await this._transformDocument(document);
@@ -51,5 +53,7 @@ export abstract class MappingDocumentTransformer extends BaseDocumentTransformer
     return newDocuments;
   }
 
-  abstract _transformDocument(document: Document): Promise<Document>;
+  abstract _transformDocument(
+    document: DocumentInterface
+  ): Promise<DocumentInterface>;
 }

langchain-core/src/embeddings.ts

@@ -6,11 +6,30 @@ import { AsyncCaller, AsyncCallerParams } from "./utils/async_caller.js";
  */
 export type EmbeddingsParams = AsyncCallerParams;
 
+export interface EmbeddingsInterface {
+  /**
+   * An abstract method that takes an array of documents as input and
+   * returns a promise that resolves to an array of vectors for each
+   * document.
+   * @param documents An array of documents to be embedded.
+   * @returns A promise that resolves to an array of vectors for each document.
+   */
+  embedDocuments(documents: string[]): Promise<number[][]>;
+
+  /**
+   * An abstract method that takes a single document as input and returns a
+   * promise that resolves to a vector for the query document.
+   * @param document A single document to be embedded.
+   * @returns A promise that resolves to a vector for the query document.
+   */
+  embedQuery(document: string): Promise<number[]>;
+}
+
 /**
  * An abstract class that provides methods for embedding documents and
  * queries using LangChain.
  */
-export abstract class Embeddings {
+export abstract class Embeddings implements EmbeddingsInterface {
   /**
    * The async caller should be used by subclasses to make any async calls,
    * which will thus benefit from the concurrency and retry logic.

langchain-core/src/example_selectors/conditional.ts

@@ -1,6 +1,6 @@
 import type { BaseChatModel } from "../language_models/chat_models.js";
 import type { BasePromptTemplate } from "../prompts/base.js";
-import type { BaseLanguageModel } from "../language_models/base.js";
+import type { BaseLanguageModelInterface } from "../language_models/base.js";
 import type { BaseLLM } from "../language_models/llms.js";
 import type { PartialValues } from "../utils/types.js";
 
@@ -20,7 +20,7 @@ export abstract class BasePromptSelector {
    * @param llm The language model for which to get a prompt.
    * @returns A prompt template.
    */
-  abstract getPrompt(llm: BaseLanguageModel): BasePromptTemplate;
+  abstract getPrompt(llm: BaseLanguageModelInterface): BasePromptTemplate;
 
   /**
    * Asynchronous version of `getPrompt` that also accepts an options object
@@ -30,7 +30,7 @@ export abstract class BasePromptSelector {
    * @returns A Promise that resolves to a prompt template.
    */
   async getPromptAsync(
-    llm: BaseLanguageModel,
+    llm: BaseLanguageModelInterface,
     options?: BaseGetPromptAsyncOptions
   ): Promise<BasePromptTemplate> {
     const prompt = this.getPrompt(llm);
@@ -47,14 +47,17 @@ export class ConditionalPromptSelector extends BasePromptSelector {
   defaultPrompt: BasePromptTemplate;
 
   conditionals: Array<
-    [condition: (llm: BaseLanguageModel) => boolean, prompt: BasePromptTemplate]
+    [
+      condition: (llm: BaseLanguageModelInterface) => boolean,
+      prompt: BasePromptTemplate
+    ]
   >;
 
   constructor(
     default_prompt: BasePromptTemplate,
     conditionals: Array<
       [
-        condition: (llm: BaseLanguageModel) => boolean,
+        condition: (llm: BaseLanguageModelInterface) => boolean,
         prompt: BasePromptTemplate
       ]
     > = []
@@ -70,7 +73,7 @@ export class ConditionalPromptSelector extends BasePromptSelector {
    * @param llm The language model for which to get a prompt.
    * @returns A prompt template.
    */
-  getPrompt(llm: BaseLanguageModel): BasePromptTemplate {
+  getPrompt(llm: BaseLanguageModelInterface): BasePromptTemplate {
     for (const [condition, prompt] of this.conditionals) {
       if (condition(llm)) {
         return prompt;
@@ -84,14 +87,16 @@ export class ConditionalPromptSelector extends BasePromptSelector {
  * Type guard function that checks if a given language model is of type
  * `BaseLLM`.
  */
-export function isLLM(llm: BaseLanguageModel): llm is BaseLLM {
+export function isLLM(llm: BaseLanguageModelInterface): llm is BaseLLM {
   return llm._modelType() === "base_llm";
 }
 
 /**
  * Type guard function that checks if a given language model is of type
  * `BaseChatModel`.
  */
-export function isChatModel(llm: BaseLanguageModel): llm is BaseChatModel {
+export function isChatModel(
+  llm: BaseLanguageModelInterface
+): llm is BaseChatModel {
   return llm._modelType() === "base_chat_model";
 }

langchain-core/src/example_selectors/semantic_similarity.ts

@@ -1,5 +1,9 @@
 import type { Embeddings } from "../embeddings.js";
-import type { VectorStore, VectorStoreRetriever } from "../vectorstores.js";
+import type {
+  VectorStoreInterface,
+  VectorStoreRetrieverInterface,
+  VectorStore,
+} from "../vectorstores.js";
 import type { Example } from "../prompts/base.js";
 import { Document } from "../documents/document.js";
 import { BaseExampleSelector } from "./base.js";
@@ -15,7 +19,7 @@ function sortedValues<T>(values: Record<string, T>): T[] {
  * class.
  */
 export type SemanticSimilarityExampleSelectorInput<
-  V extends VectorStore = VectorStore
+  V extends VectorStoreInterface = VectorStoreInterface
 > =
   | {
       vectorStore: V;
@@ -26,7 +30,7 @@ export type SemanticSimilarityExampleSelectorInput<
       vectorStoreRetriever?: never;
     }
   | {
-      vectorStoreRetriever: VectorStoreRetriever<V>;
+      vectorStoreRetriever: VectorStoreRetrieverInterface<V>;
       exampleKeys?: string[];
       inputKeys?: string[];
       vectorStore?: never;
@@ -64,9 +68,9 @@ export type SemanticSimilarityExampleSelectorInput<
  * ```
  */
 export class SemanticSimilarityExampleSelector<
-  V extends VectorStore = VectorStore
+  V extends VectorStoreInterface = VectorStoreInterface
 > extends BaseExampleSelector {
-  vectorStoreRetriever: VectorStoreRetriever<V>;
+  vectorStoreRetriever: VectorStoreRetrieverInterface<V>;
 
   exampleKeys?: string[];