Question

I am learning Prolog using SWI-Prolog.
Here is my practice code in file fact.pl:

factorial(N,F) :- N is 0, F is 1;
              N > 0, M is N - 1, factorial(M,G), F is N*G.

While I was trying to load this file by using [fact.pl], the interpreter gives me the following error:

?- [fact.pl].
ERROR: Syntax error: Operator expected
ERROR: [fact
ERROR: ** here **
ERROR: .pl] .

I am not sure how this happens, and I am pretty sure what I have done is the standard program loading command.

Anyone has ever seen this please help, thank you.

Answer 1

either ?- [fact]. or ?- ['fact.pl']. should work