Windows scryer-prolog picking up .scryerrc?

[dougransom]

I would have expected an error or warning on startup that scryer-prolog isn't loading an .scryerrc file, or that it is invalid.

PS C:\Users\doug\code\life> cat ~/.scryerrc
gjsfd;gkdsf; dfgsfdgk
:- use_module(library(lists)).
:- use_module(library(dcgs)).
:- use_module(library(reif)).
:- use_module(library(clpz)).
:- write("hello").
hello("World").
:- set_prolog_flag(occurs_check, error).

hello("World").
:- set_prolog_flag(occurs_check, error).
PS C:\Users\doug\code\life> scryer-prolog.exe
?- hello(X).
   error(existence_error(procedure,hello/1),hello/1).
?-  

I would propose a feature scryer-prolog --verbose cargo:0.9.2, ~=c:\users\doug preload=c:\users\doug.scryerrc contains:

:- use_module(library(lists)).
:- use_module(library(dcgs)).
:- use_module(library(reif)).
:- use_module(library(clpz)).
:- write("hello").
hello("World").
:- set_prolog_flag(occurs_check, error).

Also, environment and command line overrides for the .scryerrc name and location.

More info:

PS C:\Users\doug\code\life> C:\users\doug\code\scryer-prolog\target\debug\scryer-prolog.exe -v
v0.9.2-94-g9114c982
PS C:\Users\doug\code\life>

and the folder appears correct for .scryerrc

PS C:\Users\doug\code\life> ls ~/.scr*    

    Directory: C:\Users\doug

Mode                 LastWriteTime         Length Name
----                 -------------         ------ ----
-a---          2023-09-26  9:32 AM           1254 .scryer_history
-a---          2023-09-26  9:23 AM            452 .scryerrc

[triska]

On OSX, with the ~/.scryerrc you posted, I get:

$ scryer-prolog
   error(permission_error(modify,static_procedure,(;)/2),load/1).

Note that an error occurs when loading the file. Maybe this error message is not correctly shown on Windows? Could you please try to construct a smaller example that also exhibits unintended behaviour?

For example, with ~/.scryerrc consisting of:

:- initialization(write_term("hello!", [double_quotes(true)])).

I get:

$ scryer-prolog
"hello!"
?- 

Can you reproduce this?

[dougransom]

No, that is why i tried putting syntax errors at the beginning. I get:

PS C:\Users\doug\code\life> scryer-prolog.exe 
?-

which makes me think scryer is failing to open the file on windows.

Can you please point me to the rust file that would load this file, and where it determines where my home folder is?

The .scryer_history seems to be updated correctly.

[triska]

.scryerrc is loaded by toplevel.pl, please see this section of the code:

https://github.com/mthom/scryer-prolog/blob/0bfb08e464a16407ac899935961d84a9f3c925e2/src/toplevel.pl#L18

I hope you can use this as a starting point for finding out more information about this issue!

[dougransom]

I am probably missing something required to run load_scryerrc or print_help?

PS C:\Users\doug> scryer-prolog.exe
?- load_scryerrc.
   error(existence_error(procedure,load_scryerrc/0),load_scryerrc/0).
?- print_help.
   error(existence_error(procedure,print_help/0),print_help/0).
?-

if you can let me know what to type at the ?- I can probably make some progress.

[triska]

Please try to track down the problem systematically: As a starting point, you can copy the definition of load_scryerrc/0 and put it in your own Prolog file, where you can also load the libraries that are needed to run the code.

On this custom definition, you can use the predicates from library(debug), notably ($)/1, to trace the execution of each goal that occurs in the definition of the predicate.

However, in this concrete case, debugging and interacting is complicated by the fact that a few predicates (namely exactly those starting with $...) that occur in the definition are internal predicates that cannot be debugged in this way, and also cannot be called interactively on the toplevel. To test them interactively, you have to define your own auxiliary predicates that you can invoke on the toplevel.

For example, we can define:

hd(HD) :- '$home_directory'(HD).

And in this way ask Scryer about the home directory:

?- hd(HD).

In your case, what is the answer to this query?

In this way, you can systematically find out more about the situation on your platform.

[dougransom]

?- X="C:/Users/doug/.scryerrc",atom_chars(Y,X),file_exists(X),use_module(Y).
   X = "C:/Users/doug/.scry ...", Y = 'C:/Users/doug/.scryerrc'.
?-

doesn't make available the predicates in .scryerrc . makes me suspect use_module/1 perhaps doesn't load files with a full path.

This is also suspicious though. I don't know what to make of it.

 X="C:\\Users\\doug\\.scryerrc",atom_chars(Y,X),file_exists(X),use_module(library(Y)).

   error(existence_error(source_sink,library('C:\\Users\\doug\\.scryerrc')),load/1).
?-

PS C:\Users\doug\code\life> ls C:\Users\doug\.scryerrc | Format-Table 

    Directory: C:\Users\doug

Mode                 LastWriteTime         Length Name
----                 -------------         ------ ----
-a---          2023-09-27  7:45 PM            250 .scryerrc

changing slashes doesn't help.

?- X="C:/Users/doug/.scryerrc",atom_chars(Y,X),file
_exists(X),use_module(library(Y)).
   error(existence_error(source_sink,library('C:/Users/doug/.scryerrc')),load/1).
?-

[rujialiu]

It looks like most scryer-prolog devs are not working on windows? I can take a look at this (but no guarantee when) since I work on Windows everyday (but I don't use .scryerrc so I didn't found this issue) @triska

[rujialiu]

I just tried and it looks like my scryer-prolog loads .scryerrc because :- initialization(write_term("hello!", [double_quotes(true)])). prints "hello" successfully, both in Power Shell and plain old cmd.exe. And probably a verbose mode @dougransom proposes is a good idea because if I'm facing this problem I would insert a log of println! to find out what's wrong, but for a non-rust user, it's almost impossible.

[rujialiu]

It looks like @dougransom built that exe himself. Is it possible that something wrong with its build process (because load_scryerrc is not found but it should be bundled)? Maybe some kind of "nightly binary download" can help in this case we can be sure we're testing exactly the same executable. @triska

[rujialiu]

My bad. load_scryerrc is bundled but not exposed. I cannot call it in toplevel either.

[dougransom]

I indeed am using a local build as it has the fix for whitespace.

[triska]

load_scryerrc/0 is local to the module $toplevel, you can invoke it as:

?- '$toplevel':load_scryerrc.

For easier debugging and testing, you can also simply copy its definition to your own program.

[dougransom]

I am giving up on this for now, and on scryer on windows for now also. I don't have the skills to help solve this issue. Seems pretty key that this works though, consider pulling the windows support completely for now - you may be more likely to have aggrevrated users who can't get many examples like those published online by @triska or than fans.

I do think there should be a warning for a nonexistant .sryerrrc since one cannot tell between silent failure and just saving the file as the wrong file name or location.

[triska]

The usefulness of the initialization file is currently also limited by #1775.

If you want, you can as a workaround invoke Scryer Prolog with the -g switch to load any libraries you need, in lieu of .scryerrc.

For instance:

$ scryer-prolog -g 'use_module(library(lists)),use_module(library(format))'
?- maplist(portray_clause, "hello").
h.
e.
l.
l.
o.
   true.

You can add this to a script so that Scryer is always started in this way.

[mthom]

I finally got VS Code working with Scryer in a Windows 11 virtualbox. Looking at it now. file_exists does not work on Windows.. or at least, it cannot find .scryerrc. It can't find hidden files.

EDIT: I was wrong, it can find hidden files! I had my .scryerrc as .scryerrc.txt.

@dougransom I can see you haven't fallen prey to this like I did. You've moved your .scryerrc to C:\Users\doug, so I'm not sure what is happening. Is your home directory pointing elsewhere? @triska pointed out how to use a custom hd/1 (home directory) predicate to print it to a string at the toplevel. To enter it:

$> cargo run
?- [user].
hd(X) :- '$home_directory'(X).
end_of_file.
?- hd(X).
% what is the answer here?

When I do it in my virtualbox Windows, I get:

?- hd(X).
X = "C:\\Users\\Mark".

[dougransom]

PS C:\Users\doug> cargo run error: could not find Cargo.tomlinC:\Users\doug or any parent directory. So stuck there, I gather that is some rust issue. Yahk shaving…

I have since downloaded scryer-prolog 0.93, at least a i think i have, as -v reports `PS C:\Users\doug> scryer-prolog.exe -v

126d7bb-modified`.

[dougransom]

On windows there usually isn't a HOME or home_directory environment variable. I did add both to "%UserProfile%", doesn't seem to help loading .scryerrc.

[bakaq]

So stuck there, I gather that is some rust issue. Yahk shaving…

To compile and run Scryer from source, if that is what you were trying to do, you need to clone the repository to some folder and then run cargo run there, not in your home folder.