Installation & Setup

Setting up langchain-hs in your Haskell project using Stack, Cabal, or Nix.

Requirements

• GHC: 9.6.x through 9.10.x supported (GHC 9.6.7 recommended)
• Stack (>= 2.9) or Cabal (>= 3.8)
• Local LLM provider (e.g. Ollama) or API keys (OpenAI, Gemini, OpenRouter)

Adding to Your Project

langchain-hs is structured into three composable packages. Depending on your needs, you can depend on the full umbrella package or just the pure core.

Using Stack

Add the packages and required extra dependencies to your stack.yaml:

resolver: lts-22.44 # Or nightly / lts-23+

packages:
  - .

extra-deps:
  # langchain-hs packages (or from Hackage)
  - langchain-hs-0.5.0.0
  - langchain-hs-graph-0.5.0.0
  - langchain-hs-core-0.2.0.0

  # Upstream dependencies
  - git: https://github.com/tusharad/ollama-haskell
    commit: e38a92529d83303c5d05c38b73d73a278721700e
  - git: https://github.com/MercuryTechnologies/openai
    commit: 2031a05135b892a82b461558d19b813ab67cfb8f
  - git: https://github.com/lbobylev/format-heavy
    commit: 81196f86a16de8378a0ad264bf12af42c5ca7b65
  - mcp-server-0.2.0.1

In your package.yaml (or .cabal file):

dependencies:
  - base >= 4.14 && < 5
  - text
  - langchain-hs

Using Cabal

Add to your cabal.project or .cabal build-depends:

build-depends:
    base >= 4.14 && < 5,
    text,
    langchain-hs >= 0.5.0

Canonical Import: Langchain.Prelude

langchain-hs provides a unified prelude module that exposes all common constructors, operators, types, and runners:

{-# LANGUAGE OverloadedStrings #-}

import Langchain.Prelude