Best AI Coding Tools for Haskell

Our Top Picks for Haskell

We've tested the leading AI coding tools specifically for Haskell development. Here's how they rank based on code accuracy, language-specific features, and overall developer experience.

How We Evaluated These Tools

Quick Comparison Table

Haskell Stack Signals

Haskell Development Fit Snapshot

Prompting Playbook for Haskell

• Always include the full type signatures for the functions you want implemented -- Haskell's type system is the primary contract and AI tools use it to guide code generation
• List the GHC extensions enabled in your module (OverloadedStrings, DeriveGeneric, etc.) so the AI generates code compatible with your extension set
• Specify whether you use mtl-style transformers, ReaderT pattern, or an effect system (polysemy, effectful) for your application monad
• When asking for servant API code, include your API type definition so the AI generates handler implementations with matching types
• Mention your preferred string type (Text, ByteString, String) and whether you use lens, optics, or manual record accessors

Servant API handler with database access

A Servant API endpoint demonstrating type-safe routing, ReaderT application monad, and database access -- a practical pattern where AI tools can generate compilable Haskell.

{-# LANGUAGE DataKinds #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE DeriveGeneric #-}

module Api.Users where

import Data.Aeson (ToJSON, FromJSON)
import GHC.Generics (Generic)
import Servant
import Control.Monad.Reader (asks)
import qualified Database.PostgreSQL.Simple as PG

data User = User
  { userId    :: Int
  , userName  :: Text
  , userEmail :: Text
  } deriving (Generic, Show)

instance ToJSON User
instance FromJSON User

type UserAPI =
       "users" :> Get '[JSON] [User]
  :<|> "users" :> Capture "id" Int :> Get '[JSON] User

userHandlers :: ServerT UserAPI AppM
userHandlers = listUsers :<|> getUser

listUsers :: AppM [User]
listUsers = do
  conn <- asks dbConnection
  liftIO $ PG.query_ conn "SELECT id, name, email FROM users"

getUser :: Int -> AppM User
getUser uid = do
  conn <- asks dbConnection
  rows <- liftIO $ PG.query conn "SELECT id, name, email FROM users WHERE id = ?" (PG.Only uid)
  case rows of
    [user] -> pure user
    _      -> throwError err404

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