Picat example

quokkas.pi

import cp.  
import util.

day(1) = wed. 
day(2) = thurs.
day(3) = fri.
day(4) = sat. 
day(5) = sun.

clearsky(3).
clearsky(4).

car(pinnacles).
car(thetis).
car(mauritian).

allday(freemantle).
allday(rottnest).
allday(thetis).

outofcity(Day, Sched) => Sched.get(rottnest) = Day.
outofcity(Day, Sched) => 
  carday(Day, Sched),
  carday(D2, Sched),
  D2 > Day.


food(mauritian).


incompat(freemantle, kingspark).
incompat(mint, kingspark).
incompat(Act, CarAct) :- 
  member(Act, [freemantle, rottnest]), 
  car(CarAct).

incompat(AllDayAct, Other) :-
  allday(AllDayAct),
  not minor(Other).

minor(Act) => food(Act); Act = stargazing.

dayfor(Event, Sched) = Sched.get(Event).
diffdays(Act1, Act2, Sched) => 
  dayfor(Act1, Sched) != dayfor(Act2, Sched).

incompat_rule(Sched) =>
  foreach(I in Sched.keys, J in Sched.keys, I != J)
    if incompat(I, J) then diffdays(I, J, Sched) end
  end.
 
carday(Day, Sched) ?=>
  car(X),
  dayfor(X, Sched) = Day.
  
car_rule(Sched) =>
  not (
    carday(D1, Sched),
    carday(D2, Sched),
    D1 > D2 + 1
    ),
  not carday(5, Sched).

stargazing_rule(Sched) =>
  Starday = dayfor(stargazing, Sched),
  outofcity(Starday, Sched),
  clearsky(Starday).

schedule(Sched) =>
  Sched = new_map([pinnacles = D1, thetis = D2, freemantle = D3, rottnest = D4, kingspark = D5, mauritian = D6, mint= D7, stargazing = D8]),
  Days = 1..5,
  foreach(V in Sched.values) member(V, Days) end,

  incompat_rule(Sched),
  [D: D in Days, carday(D, Sched)].len == 2,
  dayfor(rottnest, Sched).day != sun,
  stargazing_rule(Sched),
  car_rule(Sched),

  nl.

main => 
  schedule(Sched),
  foreach(D in 1..5)
    Str = join([to_string(A) : A in Sched.keys, Sched.get(A) = D], ", ") ,
    writef("%w: %s\n", day(D), Str),
  end.

quokkas_better.pi

import cp.  
import util.

day(1) = wed. 
day(2) = thurs.
day(3) = fri.
day(4) = sat. 
day(5) = sun.

clearsky(3).
clearsky(4).

car(pinnacles).
car(thetis).
car(mauritian).

allday(freemantle).
allday(rottnest).
allday(thetis).

outofcity(Day, Sched) => dayfor(rottnest, Sched) =  Day.
outofcity(Day, Sched) => 
  carday(Day, Sched),
  carday(D2, Sched),
  D2 > Day. % come back this day


food(mauritian).


incompat(freemantle, kingspark).
incompat(mint, kingspark).
incompat(Act, CarAct) :- 
  member(Act, [freemantle, rottnest]), 
  car(CarAct).

incompat(AllDayAct, Other) :-
  allday(AllDayAct),
  not minor(Other).

minor(Act) => food(Act); Act = stargazing.

dayfor(Event, Sched) = Day => member({Event, Day}, Sched). 
diffdays(Act1, Act2, Sched) => 
  dayfor(Act1, Sched) != dayfor(Act2, Sched).

incompat_rule(Sched) =>
  foreach({A1, D1} in Sched, {A2, D2} in Sched, A1 != A2)
    if incompat(A1, A2) then D1 != D2 end
  end.
 
carday(Day, Sched) =>
  car(X),
  member({X, Day}, Sched).
  
car_rule(Sched) =>
  not (
    carday(D1, Sched),
    carday(D2, Sched),
    D1 > D2 + 1
    ),
  not carday(5, Sched).

stargazing_rule(Sched) =>
  Starday = dayfor(stargazing, Sched),
  outofcity(Starday, Sched),
  clearsky(Starday).

schedule(Sched) =>
  Sched = [{pinnacles, D1}, 
           {thetis, D2}, 
           {freemantle, D3}, 
           {rottnest, Rottday},
           {kingspark, D5},
           {mauritian, D6},
           {mint, D7},
           {stargazing, D8}
          ],
  Days = 1..5,
  foreach({A, B} in Sched) member(B, Days) end,

  incompat_rule(Sched),
  [D: D in Days, carday(D, Sched)].len == 2,
  day(Rottday) != sun,
  stargazing_rule(Sched),
  car_rule(Sched),

  nl.

main => 
  schedule(Sched),
  foreach(D in 1..5)
    Str = [to_string(A) : {A, D} in Sched], 
    writef("%w: %s\n", day(D), join(Str, ", ")),
  end,
  nl.