flix-datalog-comparison-test.clj

flix-datalog-comparison-test.clj

(with-open [n (xt/start-node {})]
  (xt/q (xt/db n) '{:find [component date]
                    :where [(ready-date component date)]
                    :rules [[(ready-date part date)
                             (delivery-date part date)]
                            [(ready-date part date)
                             [(+ assembly-time* component-date) date]
                             (part-depends part component)
                             (assembly-time part assembly-time*)
                             (ready-date component component-date)]
                            [(delivery-date part date)
                             [(identity [["Chassis" 2]
                                         ["Piston" 1]
                                         ["Ignition" 7]]) [[part date]]]]
                            [(assembly-time part assembly-time)
                             [(identity [["Car" 7]
                                         ["Engine" 2]]) [[part assembly-time]]]]
                            [(part-depends part component)
                             [(identity [["Car" "Chassis"]
                                         ["Car" "Engine"]
                                         ["Engine" "Piston"]
                                         ["Engine" "Ignition"]]) [[part component]]]]]}))
;; => #{["Car" 16] ["Car" 9] ["Engine" 9] ["Chassis" 2] ["Piston" 1] ["Car" 10] ["Engine" 3] ["Ignition" 7]}
;;
;; vs.
;; https://flix.dev/

;; Datalog Enriched with Lattice Semantics
;;Flix supports Datalog constraints enriched with lattice semantics.

;;The program on the right computes the delivery date for a collection of parts. Each part is assembled from a collection of sub-components with various delivery dates. For example, a car depends on a chassis and an engine. To build a car, we need to wait for the chassis and engine to assembled and then we can assemble the car itself.

;;Note that parts may depend on sub-components that themselves may depend on other sub-components. In other words, the problem is recursive.

;;Datalog constraints enriched with lattice semantics is one of the more advanced features of Flix and requires some background knowledge of lattice theory and fixpoints.

;;let p = #{
;;    /// Parts and the components they depend on.
;;    PartDepends("Car",       "Chassis").
;;    PartDepends("Car",       "Engine").
;;    PartDepends("Engine",    "Piston").
;;    PartDepends("Engine",    "Ignition").
;;
;;    /// Time required to assemble a part from its components.
;;    AssemblyTime("Car",     7).
;;    AssemblyTime("Engine",  2).
;;
;;    /// Expected delivery date for certain components.
;;    DeliveryDate("Chassis";  2).
;;    DeliveryDate("Piston";   1).
;;    DeliveryDate("Ignition"; 7).
;;
;;    /// A part is ready when it is delivered.
;;    ReadyDate(part; date) :-
;;        DeliveryDate(part; date).
;;
;;    /// Or when it can be assembled from its components.
;;    ReadyDate(part; assemblyTime + componentDate) :-
;;        PartDepends(part, component),
;;        AssemblyTime(part, assemblyTime),
;;        ReadyDate(component; componentDate).
;;};
;;// Computes the delivery date for each component.
;;let r = query p select (c; d) from ReadyDate(c; d)