Basic example of using HaskellDB to unmap records of a table

Suppose that I have the following (PostgreSQL) table definition:

CREATE TABLE books (
    id serial NOT NULL,
    title character varying NOT NULL,

    PRIMARY KEY (id)
);

And the following record definition:

data Book = 
  { id :: Int
  , title :: String
  }

What is a basic example of an "unmap" function to query all books in the database, allBooks :: Database -> IO [Book]?