Language

• Accidental optimization via I/O indirection
• Applicative do-notation
• Lameda Calculus evaluator
• Monadic parsing in Haskell (Maybe)

MySQL

• Databases in Haskell with mysql-simple

Nix

• Haskell development with Nix
• Simpler Haskell development with Nix

Scotty

• Request suspension in Scotty with MVar
• Request suspension in Scotty with STM

Yesod

• Yesod Web Framework Book