feat: Bootstrap langchain_core package (#329)

packages/langchain_core/CHANGELOG.md

@@ -0,0 +1,3 @@
+## 0.0.1-dev.1
+
+- Bootstrap package.

packages/langchain_core/README.md

@@ -0,0 +1,68 @@
+# 🦜️🔗 LangChain.dart Core
+
+[![tests](https://img.shields.io/github/actions/workflow/status/davidmigloz/langchain_dart/test.yaml?logo=github&label=tests)](https://github.com/davidmigloz/langchain_dart/actions/workflows/test.yaml)
+[![docs](https://img.shields.io/github/actions/workflow/status/davidmigloz/langchain_dart/pages%2Fpages-build-deployment?logo=github&label=docs)](https://github.com/davidmigloz/langchain_dart/actions/workflows/pages/pages-build-deployment)
+[![langchain_core](https://img.shields.io/pub/v/langchain_core.svg)](https://pub.dev/packages/langchain_core)
+[![](https://dcbadge.vercel.app/api/server/x4qbhqecVR?style=flat)](https://discord.gg/x4qbhqecVR)
+[![MIT](https://img.shields.io/badge/license-MIT-purple.svg)](https://github.com/davidmigloz/langchain_dart/blob/main/LICENSE)
+
+## What is it?
+
+LangChain.dart Core contains the base abstractions that power the rest of the [LangChain.dart](https://github.com/davidmigloz/langchain_dart) ecosystem.
+
+These abstractions are designed to be as modular and simple as possible. Examples of these abstractions include those for language models, document loaders, embedding models, vector stores, retrievers, and more.
+
+The benefit of having these abstractions is that any provider can implement the required interface and then easily be used in the rest of the LangChain ecosystem.
+
+For full documentation see the [API reference](https://pub.dev/documentation/langchain_core/latest/).
+
+## Core Interface: Runnables
+
+The concept of a Runnable is central to LangChain Core – it is the interface that most LangChain Core components implement, giving them
+
+- a common invocation interface (invoke, batch, stream, etc.)
+- built-in utilities for retries, fallbacks, schemas and runtime configurability
+
+For more check out the [runnable docs](https://langchaindart.com/#/expression_language/interface). Examples of components that implement the interface include: LLMs, Chat Models, Prompts, Retrievers, Tools, Output Parsers.
+
+You can use LangChain Core objects in two ways:
+
+1. **imperative**, i.e. call them directly, eg. `model.invoke(...)`
+
+2. **declarative**, with LangChain Expression Language (LCEL)
+
+3. or a mix of both! eg. one of the steps in your LCEL sequence can be a custom function
+
+## What is LangChain Expression Language?
+
+LangChain Expression Language (LCEL) is a _declarative language_ for composing LangChain Core runnables into sequences (or DAGs), covering the most common patterns when building with LLMs.
+
+LangChain Core compiles LCEL sequences to an _optimized execution plan_, with automatic parallelization, streaming, and tracing support.
+
+For more check out the [LCEL docs](https://langchaindart.com/#/expression_language/interface).
+
+![Diagram outlining the hierarchical organization of the LangChain.dart framework, displaying the interconnected parts across multiple layers.](https://python.langchain.com/assets/images/langchain_stack-f21828069f74484521f38199910007c1.svg "LangChain Framework Overview")
+
+## Contributing
+
+New contributors welcome! Check out our
+[Contributors Guide](https://github.com/davidmigloz/langchain_dart/blob/main/CONTRIBUTING.md) for
+help getting started.
+
+Join us on [Discord](https://discord.gg/x4qbhqecVR) to meet other maintainers. We'll help you get
+your first contribution in no time!
+
+
+## Why build on top of LangChain Core?
+
+The whole LangChain.dart ecosystem is built on top of LangChain Core, so you're in good company when building on top of it. Some of the benefits:
+
+- **Modularity**: LangChain Core is designed around abstractions that are independent of each other, and not tied to any specific model provider.
+- **Stability**: We are committed to a stable versioning scheme, and will communicate any breaking changes with advance notice and version bumps.
+- **Battle-tested**: LangChain Core components have the largest install base in the LLM ecosystem, and are used in production by many companies.
+- **Community**: LangChain Core is developed in the open, and we welcome contributions from the community.
+
+## License
+
+LangChain.dart is licensed under the
+[MIT License](https://github.com/davidmigloz/langchain_dart/blob/main/LICENSE).

packages/langchain_core/lib/langchain_core.dart

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+/// Contains core abstractions of LangChain.dart and the LangChain Expression Language (LCEL).
+library;

packages/langchain_zapier/pubspec.yaml → packages/langchain_core/pubspec.yaml

@@ -1,11 +1,10 @@
-name: langchain_zapier
-description: Zapier module for LangChain.dart.
+name: langchain_core
+description: Contains core abstractions of LangChain.dart and the LangChain Expression Language (LCEL).
 version: 0.0.1-dev.1
-repository: https://github.com/davidmigloz/langchain_dart/tree/main/packages/langchain_zapier
-issue_tracker: https://github.com/davidmigloz/langchain_dart/issues
+repository: https://github.com/davidmigloz/langchain_dart/tree/main/packages/langchain_core
+issue_tracker: https://github.com/davidmigloz/langchain_dart/issues?q=label:p:langchain_core
 homepage: https://github.com/davidmigloz/langchain_dart
 documentation: https://langchaindart.com
-publish_to: none # Remove when the package is ready to be published
 
 topics:
   - ai
@@ -17,8 +16,7 @@ environment:
   sdk: ">=3.0.0 <4.0.0"
 
 dependencies:
-  langchain: ^0.4.1
   meta: ^1.9.1
 
 dev_dependencies:
-  test: ^1.24.3
+  test: ^1.24.5