Exploring Racket's Datalog implementation

family.rkt

#lang datalog

% -- facts -- %
female(georgene).
female(randi).
female(nikki).
female(jenny).
female(jen).
female(taylor).

male(randy).
male(leslie).
male(wesley).
male(christian).
male(sebastian).
male(rob).

parent(jenny, christian).
parent(leslie, christian).
parent(christian, sebastian).
parent(christian, nikki).
parent(randi, nikki).
parent(randi, sebastian).
parent(georgene, randi).
parent(randy, randi).
parent(georgene, rob).
parent(randy, rob).
parent(rob, taylor).
parent(jen, taylor).

% -- rules -- %

father(X, Y) :-
  male(X),
  parent(X, Y).

mother(X, Y) :-
  female(X),
  parent(X, Y).

mom(X, Y) :-
  mother(X, Y).

dad(X, Y) :-
  father(X, Y).

spouse(X, Y) :-
  parent(X, C),
  parent(Y, C),
  X != Y.

son(X, Y) :-
  male(X),
  parent(Y, X).

daughter(X, Y) :-
  female(X),
  parent(Y, X).

child(X, Y) :-
  parent(Y, X).

grandparent(X, Y) :-
  parent(X, Z),
  parent(Z, Y).

grandfather(X, Y) :-
  father(X, Z),
  parent(Z, Y).

grandmother(X, Y) :-
  mother(X, Z),
  parent(Z, Y).

grandchild(X, Y) :-
  child(X, Z),
  child(Z, Y).

grandson(X, Y) :-
  male(X),
  grandchild(X, Y).

granddaughter(X, Y) :-
  female(X),
  grandchild(X, Y).

sibling(X, Y) :-
  parent(Z, X),
  parent(Z, Y),
  X != Y.

parent-sibling(X, Y) :-
  parent(P, Y),
  sibling(P, X).

aunt(X, Y) :-
  parent-sibling(X, Y),
  female(X).

uncle(X, Y) :-
  parent-sibling(X, Y),
  male(X).

% spouse's siblings
sibling-in-law(X, Y) :-
  spouse(X, S),
  sibling(S, Y).

% sibling's spouses
sibling-in-law(X, Y) :-
  sibling(X, S),
  spouse(S, Y).

parent-in-law(X, Y) :-
  spouse(X, S),
  parent(Y, S).

in-law(X, Y) :-
  parent-in-law(X, Y).
  
in-law(X, Y) :-
  sibling-in-law(X, Y).

brother-in-law(X, Y) :-
  sibling-in-law(X, Y),
  male(Y).

sister-in-law(X, Y) :-
  sibling-in-law(X, Y),
  female(Y).

% -- queries / tests -- %
sister-in-law(randi, S)?
sister-in-law(jen, S)?

brother-in-law(christian, S)?
brother-in-law(rob, S)?

aunt(R, taylor)?
uncle(R, nikki)?
sibling(nikki, S)?
mom(M, christian)?