Prolog

Prolog

Puzzles solved with logic programming using SWI-Prolog language.

Default goal

$ swipl -g solve -s farmer.pro

Replace farmer with the desired puzzle.

Interactive console

$ swipl -s farmer.pro

?- solve(30, 74, Chickens, Cows).

% Chickens = 23,
% Cows = 7.

% Exit with Ctrl^C + e or halt.

$ swipl -s "../Layton/Curious Village/128-curious-lock.pro"

solve([A,B,C,D,E,F,G]), display_lock_nl([A,B,C,D,E,F,G]).

3   1
4 2 9
6   8

A = 3,
B = 4,
C = 6,
D = 2,
E = 1,
F = 9,
G = 8 ;

% press ; or space for more solutions

3   8
4 2 9
6   1

A = 3,
B = 4,
C = 6,
D = 2,
E = 8,
F = 9,
G = 1 .

% press . or enter to stop

See: Executing a query

At the end of each puzzle file there is a <examples> section with example queries.

Develop

$ swipl

?- ["farmer.pro"]. % load file
?- make. % reload file
?- solve.

Debug

?- trace.
[trace]  ?- solve(30, 74, Chickens, Cows).
%    Call: (10) solve(30, 74, _51476, _51478) ? creep
%    ...
%    Exit: (10) solve(30, 74, 23, 7) ? creep
[trace]  ?- notrace.
[debug]  ?- nodebug.