About TRS The following Oz code is derived from the examples provided in the book:
"The Reasoned Schemer" by Daniel P. Friedman, William E. Byrd and Oleg Kiselyov.
http://www.ccs.neu.edu/home/matthias/BRS/

 ```TRS Chapter #06 Examples in Oz %%%%%%%%%%%%%%%%%%%%%%%%%%% From CTM Chapter 9 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % Lazy problem solving (Solve) % This is the Solve operation, which returns a lazy list of solutions % to a relational program. The list is ordered according to a % depth-first traversal. Solve is written using the computation space % operations of the Space module. fun {Solve Script} {SolStep {Space.new Script} nil} end fun {SolStep S Rest} case {Space.ask S} of failed then Rest [] succeeded then {Space.merge S}|Rest [] alternatives(N) then {SolLoop S 1 N Rest} end end fun lazy {SolLoop S I N Rest} if I>N then Rest elseif I==N then {Space.commit S I} {SolStep S Rest} else Right C in Right={SolLoop S I+1 N Rest} C={Space.clone S} {Space.commit C I} {SolStep C Right} end end fun {SolveOne F} L = {Solve F} in if L==nil then nil else [L.1] end end fun {SolveAll F} L = {Solve F} proc {TouchAll L} if L==nil then skip else {TouchAll L.2} end end in {TouchAll L} L end fun {SolveN N F} L = {Solve F} in {List.take L N} end %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % Translation Notes: %% 6.19-6.30: Need an Oz Breadth-First Solve that matches the behavior of condi % 6.31-6.38: Need an Oz Solve that matches the behavior of all and alli % 6.1 fun {Anyo G} choice {G} [] {Anyo G} end end % 6.4 fun {Nevero} {Anyo fun {\$} fail end} end % 6.5 (diverges) %{Browse 5# % {SolveOne % fun {\$} Q in % _ = {Nevero} % true = Q % end}} % 6.6 {Browse 6# {SolveOne fun {\$} Q in fail {Nevero} end}} % 6.7 fun {Alwayso} {Anyo fun {\$} skip _ end} end {Browse 7# {SolveOne fun {\$} Q in _ = {Alwayso} true = Q end}} % 6.9 (diverges) %{Browse 9# % {SolveAll % fun {\$} Q in % _ = {Alwayso} % true = Q % end}} % 6.10 {Browse 10# {SolveN 5 fun {\$} Q in _ = {Alwayso} true = Q end}} % 6.11 {Browse 11# {SolveN 5 fun {\$} Q in true = Q _ = {Alwayso} Q end}} % 6.12 fun {Salo G} choice skip _ [] {G} end end % 6.13 {Browse 13# {SolveOne fun {\$} Q in _ = {Salo Alwayso} true = Q end}} % 6.14 {Browse 14# {SolveOne fun {\$} Q in _ = {Salo Nevero} true = Q end}} % 6.15 (diverges) %{Browse 15# % {SolveAll % fun {\$} Q in % _ = {Salo Nevero} % true = Q % end}} % 6.16 (diverges) %{Browse 16# % {SolveOne % fun {\$} Q in % _ = {Salo Nevero} % fail % true = Q % end}} % 6.17 (diverges) %{Browse 17# % {SolveOne % fun {\$} Q in % _ = {Alwayso} % fail % true = Q % end}} % 6.18 (diverges) %{Browse 18# % {SolveOne % fun {\$} Q in % _ = % choice % false = Q % {Alwayso} % [] {Anyo fun {\$} true = Q end} % end % true = Q % end}} % Translation of 6.19 - 6.38 is not completed % %% 6.19 (Note: condi is a breadth-first search) % {Browse 19# % {BFSolveOne % fun {\$} Q in % _ = % choice % false = Q % {Alwayso} % [] true = Q % end % true = Q % end}} % % %% 6.20 (diverges) % %{Browse 20# % % {BFSolveN 2 % % fun {\$} Q in % % _ = % % choice % % false = Q % % {Alwayso} % % [] true = Q % % end % % true = Q % % end}} % % %% 6.21 % {Browse 21# % {BFSolveN 5 % fun {\$} Q in % _ = % choice % false = Q % {Alwayso} % [] {Anyo fun {\$} true = Q end} % end % true = Q % end}} % % %% 6.24 % fun {Teacup} % choice tea [] cup end % end % {Browse 24# % {BFSolveN 5 % fun {\$} R in % choice % {Teacup} = R % [] false = R % [] fail % end % end}} % % %% 6.25 % {Browse 25# % {BFSolveN 5 % fun {\$} Q in % _ = % choice % false = Q % {Alwayso} % [] true = Q % {Alwayso} % [] fail % end % true = Q % end}} % % %% 6.27 (diverges) % %{Browse 27# % % {SolveN 5 % % fun {\$} Q in % % _ = % % choice % % false = Q % % {Alwayso} % % [] true = Q % % {Alwayso} % % [] fail % % end % % true = Q % % end}} % % %% 6.28 % {Browse 28# % {SolveN 5 % fun {\$} Q in % _ = % choice % {Alwayso} % [] {Nevero} % end % true = Q % end}} % % %% 6.30 (diverges) % {Browse 30# % {BFSolveN 5 % fun {\$} Q in % _ = % choice % {Alwayso} % [] {Nevero} % end % true = Q % end}} % %% 6.31 % {Browse 31# % {AllSolveOne % fun {\$} Q in % choice % false = Q % [] true = Q % end % _ = {Alwayso} % true = Q % end}} % % %% 6.32 % {Browse 32# % {AllBFSolveOne % fun {\$} Q in % choice % false = Q % [] true = Q % end % _ = {Alwayso} % true = Q % end}} % % %% 6.33 % {Browse 33# % {AllBFSolveN 5 % fun {\$} Q in % choice % false = Q % [] true = Q % end % _ = {Alwayso} % true = Q % end}} % % %% 6.34 % {Browse 34# % {AllBFSolveN 5 % fun {\$} Q in % choice % true = Q % [] false = Q % end % _ = {Alwayso} % true = Q % end}} % % %% 6.36 % {Browse 36# % {AllSolveN 5 % fun {\$} Q in % choice % _=_ % [] _={Nevero} % end % _ = {Alwayso} % true = Q % end}} % % %% 6.38 (diverges) % {Browse 36# % {AllBFSolveN 5 % fun {\$} Q in % choice % _=_ % [] _={Nevero} % end % _ = {Alwayso} % true = Q % end}} ```

Chris Rathman / Chris.Rathman@tx.rr.com