I'm kinda new in Prolog and I'm using SWI-Prolog v6.6 to storage asserts in my *.pl file.
:- dynamic fact/2.
assert(fact(fact1,fact2)).
With the code above I can make asserts and it works fine, but the problem is when I close SWI-Prolog and I open the *.pl file again, the asserts i've made are gone...
There is a way to make asserts and those get stored even if I close the SWI-Prolog?
Sorry about my bad english and Thanks! (:
Saving state has certain limitations, also see the recent discussion on the SWI-Prolog mailing list.
I think the easiest way to persistently store facts on SWI-Prolog is to use the persistency library. For that I would rewrite your code in the following way:
:- use_module(library(persistency)).
:- persistent fact(fact1:any, fact2:any).
:- initialization(init).
init:-
absolute_file_name('fact.db', File, [access(write)]),
db_attach(File, []).
You can now add/remove facts using assert_fact/2, retract_fact/2, and retractall_fact/2.
Upon exiting Prolog the asserted facts are automatically saved to fact.db.
Example usage:
$ swipl my_facts.pl
?- assert_fact(some(fact), some(other,fact)).
true.
?- halt.
$ swipl my_facts.pl
?- fact(X, Y).
X = some(fact),
Y = some(other, fact).
If what you're after is just to get a list of certain facts asserted with a predicate, then mbratch's suggestion will work fine. But you may also want to save the state of your program in general, in which case you can use qsave_program/2. According to the swi docs, qsave_program(+File, +Options)
Saves the current state of the program to the file
File. The result is a resource archive containing a saved state that expresses all Prolog data from the running program and all user-defined resources.
Documentation here http://www.swi-prolog.org/pldoc/man?section=runtime
来源：https://stackoverflow.com/questions/22887418/issues-with-storage-of-facts-in-prolog