Well if we are showing off sudoku solvers, it would be a sin not to share this one: sudoku(Rows) :- length(Rows, 9), maplist(same_length(Rows

Well if we are showing off sudoku solvers, it would be a sin not to share this one: sudoku(Rows) :- length(Rows, 9), maplist(same_length(Rows), Rows), append(Rows, Vs), Vs ins 1..9, maplist(all_distinct, Rows), transpose(Rows, Columns), maplist(all_distinct, Columns), Rows = [As,Bs,Cs,Ds,Es,Fs,Gs,Hs,Is], blocks(As, Bs, Cs), blocks(Ds, Es, Fs), blocks(Gs, Hs, Is). blocks([], [], []). blocks([N1,N2,N3|Ns1], [N4,N5,N6|Ns2], [N7,N8,N9|Ns3]) :- all_distinct([N1,N2,N3,N4,N5,N6,N7,N8,N9]), blocks(Ns1, Ns2, Ns3). While not one line, to me it is pareto optimal for readable, elegant, and incredibly powerful thanks to the first class constraint solvers that ship with Scryer Prolog. If you want to learn more about it or see more of Markus's work: https://www.metalevel.at/sudoku/ https://www.metalevel.at/sudoku/ https://youtu.be/5KUdEZTu06o https://youtu.be/5KUdEZTu06o More about Scryer Prolog (a modern , performant, ISO-compliant prolog written mostly in rust) https://www.scryer.pl/ https://www.scryer.pl/ https://github.com/mthom/scryer-prolog https://github.com/mthom/scryer-prolog