Improving list comprehension database queries

The improvement of queries expressed as list comprehensions in a lazy functional language is described. The database literature identifies four algebraic and two implementation-based improvement strategies. For each strategy the authors show an equivalent improvement for queries expressed as list comprehensions. This means that well-developed database algorithms that improve queries using several of these strategies can be emulated to improve comprehension queries. They are also able to improve queries which require greater power than that provided by the relational algebra. Most of the improvements entail transforming a simple, inefficient query into a more complex, but more efficient form. The authors illustrate each improvement using examples drawn from the database literature