CSE 230 Notes, Prolog cut example

CSE 230: Principles of Programming Languages

A Prolog Cut Example awk% bp BinProlog 4.00 Copyright (C) Paul Tarau 1992-1995 by FTP from: clement.info.umoncton.ca E-MAIL to : binprolog@info.umoncton.ca (C-ified standalone) (with heap GC enabled) Finished loading system C-code (23203 instructions). Finished loading user C-code (4 instructions). ?- consult(a). % using compile/1 is MUCH faster consulting(a.pl) consulted(a.pl,time(0)) yes ?- a(X). X=2; no ?- Prolog execution halted(0). CPU time = 0.50s awk% awk% Now a trace of the computation that was done here: awk% bp BinProlog 4.00 Copyright (C) Paul Tarau 1992-1995 by FTP from: clement.info.umoncton.ca E-MAIL to : binprolog@info.umoncton.ca (C-ified standalone) (with heap GC enabled) Finished loading system C-code (23203 instructions). Finished loading user C-code (4 instructions). ?- consult(a). % using compile/1 is MUCH faster consulting(a.pl) consulted(a.pl,time(0)) yes ?- trace(a(X)). Call: a(_2244) <enter=call, other=trace>: ; !!! dynamic(a/1) Call: b <enter=call, other=trace>: ; !!! dynamic(b/0) CUT Call: c <enter=call, other=trace>: ; !!! dynamic(c/0) Call: fail <enter=call, other=trace>: ; !!! compiled(fail/0) Fail: fail Fail: c Fail: b Call: e <enter=call, other=trace>: ; !!! dynamic(e/0) Exit: e Exit: a(2) X=2; Redo: a(2) Redo: e Fail: e Fail: a(_2244) no ?- Prolog execution halted(0). CPU time = 0.33s awk%

To CSE 230 notes page
To CSE 230 homepage