dynamic-grouping.taq

$ java -jar taq.jar dynamic-grouping

Running query mega_cities_by_continent in global scope 
africa(Continent=Africa, Megacity=Cairo, Country=Egypt)
africa(Continent=Africa, Megacity=Lagos, Country=Nigeria)
africa(Continent=Africa, Megacity=Kinshasa, Country=Democratic Republic of Congo)
asia(Continent=Asia, Megacity=Tokyo, Country=Japan)
...
asia(Continent=Asia, Megacity=Hyderabad, Country=India)
europe(Continent=Europe, Megacity=Moscow, Country=Russia)
europe(Continent=Europe, Megacity=London, Country=United Kingdom)
europe(Continent=Europe, Megacity=Istanbul, Country=Turkey)
europe(Continent=Europe, Megacity=Rhine-Ruhr, Country=Germany)
europe(Continent=Europe, Megacity=Paris, Country=France)
north_america(Continent=North America, Megacity=Mexico City, Country=Mexico)
north_america(Continent=North America, Megacity=New York City, Country=United States)
north_america(Continent=North America, Megacity=Los Angeles, Country=United States)
south_america(Continent=South America, Megacity=Sao Paulo, Country=Brazil)
south_america(Continent=South America, Megacity=Buenos Aires, Country=Argentina)
south_america(Continent=South America, Megacity=Rio de Janeiro, Country=Brazil)

Description

dynamic-grouping.taq demonstrates grouping using a map operation to route each item to a specific group list. This allows the grouping to be completed in a single pass through the incoming collection. The query result shows there are 5 different export lists, one for each continent - africa, asia, europe, north_america, south_america. The map is qualified with the keyword list to indicate each mapping target is a list. Note the list names are identifiers, not text,

mega_city = list map Continent  {
    ? "Asia":          asia
    ? "Africa":        africa
    ? "Europe":        europe
    ? "South America": south_america
    ? "North America": north_america
}