# Installing & calling scasp for SWI-Prolog **URL:** \ **Category:** Pack\ **Created:** [April 4, 2022, 3:47pm UTC](https://swi-prolog.discourse.group/t/installing-calling-scasp-for-swi-prolog/5221 "2022-04-04T15:47:02Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![d-vyd](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/d-vyd/32/4191_2.png) [@d-vyd](https://swi-prolog.discourse.group/u/d-vyd)\ **Post date:** [April 4, 2022, 3:47pm UTC](https://swi-prolog.discourse.group/t/installing-calling-scasp-for-swi-prolog/5221/1 "2022-04-04T15:47:02Z")
@Jan, following the [instructions](https://github.com/JanWielemaker/sCASP), I installed a more recent version of SWI-Prolog (threaded, 64 bits, version 8.5.9) for Windows and cloned [sCASP](https://github.com/JanWielemaker/sCASP) (swipl branch). I moved to the cloned directory `?- working_directory(_,"c:/Program Files/swipl_sCASP").` and installed `?- pack_install(.).` I received a lot of “passed” results (e.g. `% birds.pl ...... passed 15 ms`) and then some suspicious results, which may or may not be relevant: ```prolog % Warning: No defined. % Warning: Too old Prolog or no writeable candidate % Warning: Could not install the scasp executable true . ``` I wasn’t trying to create or install scasp as an executable. So, no worries there. But the other warnings? And finally: ```prolog ?- use_module(library(scasp)). true. ``` However, when I try the example from the same instructions (in the Ciao sCASP section): ```prolog p(A) :- not q(A). q(A) :- not p(A). ``` The SWI-Prolog warnings box pops up for both lines, with the message `format/3: Type error: `text`expected, found`url(`c...` I think I’m supposed to query this program with `scasp(goal(p(A), [model(M), tree(T)]).` but I’m not sure how to proceed. Can you offer some guidance? Thank you -david ---
**Author:** ![jan](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/jan/32/4_2.png) [@jan](https://swi-prolog.discourse.group/u/jan)\ **Post date:** [April 4, 2022, 4:23pm UTC](https://swi-prolog.discourse.group/t/installing-calling-scasp-for-swi-prolog/5221/2 "2022-04-04T16:23:27Z")
I guess the installation has something to do with the `make` where I think the Makefile will not work for Windows. > [@d-vyd](#): > > warnings box pops up for both lines How did you enter these? This is what I get: ```prolog ?- use_module(library(scasp)). true. ?- [user]. |: p(A) :- not q(A). |: q(A) :- not p(A). |: ^D% user://1 compiled 0.00 sec, 2 clauses true. ?- ? q(X). % s(CASP) model { not p(X), q(X) }, % s(CASP) justification query ← q(X) ← not p(X) ← chs(q(X)). ``` Note the `?`, which does the scasp solve and nicely displays the results in the toplevel. scasp/2 is more for programs that wish to reason about the result. ---
**Author:** ![d-vyd](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/d-vyd/32/4191_2.png) [@d-vyd](https://swi-prolog.discourse.group/u/d-vyd)\ **Post date:** [April 5, 2022, 5:52am UTC](https://swi-prolog.discourse.group/t/installing-calling-scasp-for-swi-prolog/5221/3 "2022-04-05T05:52:29Z")
Thank you for that example @jan. On my Windows machine, I cannot terminate the pseudo-file `[user]` with CTRL-D (`^D`) or anything else I’ve tried. I can use `assertz` like so: ```prolog 1 ?- use_module(library(scasp)). true. 2 ?- assertz(p(A) :- not q(A)). true. 3 ?- assertz(q(A) :- not p(A)). true. 4 ?- ? q(X). % s(CASP) model { not p(X), q(X) }, % s(CASP) justification query ← q(X) ← not p(X) ← chs(q(X)). ``` However, I prefer to write programs in Visual Studio Code or another editor and then consult and query. When I write this in myfile.pl: ```prolog use_module(library(scasp)). p(A) :- not q(A). q(A) :- not p(A). ``` And then consult… ```prolog C:\Users\dvyd>swipl Welcome to SWI-Prolog (threaded, 64 bits, version 8.5.9) SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software. Please run ?- license. for legal details. For online help and background, visit https://www.swi-prolog.org For built-in help, use ?- help(Topic). or ?- apropos(Word). 1 ?- working_directory(_,"D:/Documents/Programming/Prolog/"). true. 2 ?- consult(myfile). ERROR: d:/documents/programming/prolog/myfile.pl:2:12: Syntax error: Operator expected ERROR: d:/documents/programming/prolog/myfile.pl:3:12: Syntax error: Operator expected true. ``` Character 12 in lines 2 and 3 is the space after “not”. What am I doing wrong? -david ---
**Author:** ![jan](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/jan/32/4_2.png) [@jan](https://swi-prolog.discourse.group/u/jan)\ **Post date:** [April 5, 2022, 6:52am UTC](https://swi-prolog.discourse.group/t/installing-calling-scasp-for-swi-prolog/5221/4 "2022-04-05T06:52:31Z")
> [@d-vyd](#): > > `use_module(library(scasp)).` ``` :- use_module(library(scasp)). ``` Note the `:-` ! As is, you define a fact use\_module/1 rather than loading the module. As the module defines `not` as a prefix operator the use of `not q(A)` becomes valid. Without it is invalid syntax. > [@d-vyd](#): > > Windows machine, I cannot terminate the pseudo-file `[user]` with CTRL-D ( `^D` ) or anything else I’ve tried. In `swipl-win.exe`, `^D` works. In the Windows console you can type `end_of_file.` Possibly `^Z` works too. Running `swipl.exe` under Wine in Linux ^Z does Linux job control ☹ But yes, you normally want to load programs from a file. ---
**Author:** ![d-vyd](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/d-vyd/32/4191_2.png) [@d-vyd](https://swi-prolog.discourse.group/u/d-vyd)\ **Post date:** [April 5, 2022, 7:37am UTC](https://swi-prolog.discourse.group/t/installing-calling-scasp-for-swi-prolog/5221/5 "2022-04-05T07:37:11Z")
ah rats, `:- use_module(library(scasp)).`, that’s a rookie mistake! Thanks @jan . OK. It is working now. I’ll experiment a bit and then post back on my original thread regarding explaining why and why not… ---
**Author:** ![jan](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/jan/32/4_2.png) [@jan](https://swi-prolog.discourse.group/u/jan)\ **Post date:** [April 5, 2022, 8:48am UTC](https://swi-prolog.discourse.group/t/installing-calling-scasp-for-swi-prolog/5221/6 "2022-04-05T08:48:34Z")
Note that you can also use the system online at [SWISH -- SWI-Prolog for SHaring](https://swish.swi-prolog.org/example/scasp.swinb). Great for simple experiments and you can share the links here for discussion.