Passing sets to procedures

[vsht]

Hi,

is there a way to define procedures with arguments being sets of variables so that one can alternate between passing an empty set {} or a nonempty one?

Something naive like

#procedure proctest(SET)
id f(s?`SET') = s;
#endprocedure

s x,y, s;
cf f;

l exp = f(x)+f(y);

.sort
#call proctest({x,y})

print +s;
.end

complains about "Arguments of procedure proctest are not matching".

It actually does what I want for #call proctest({}) and #call proctest({x}) but I guess it's only because the preprocessor calculator kicks in here.

Cheers,
Vlad

[tueda]

The reason for the Arguments of procedure proctest are not matching error is that you defined the proctest procedure to take one argument SET, but you passed 2 arguments {x and y}. You need to escape the comma as

#call proctest({x\,y})

Passing an empty set {} has another issue. Actually,

CF f;
S x;
L F = f(x);
id f(x?{}) = x;
.end

leads to a segfault.

Valgrind:

FORM 5.0.0-beta.1 (May 21 2024, v5.0.0-beta.1-66-g83e3d41)  Run: Wed Jul  3 20:56:27 2024

==11465== Invalid read of size 4
==11465==    at 0x23B2D2: CheckWild (wildcard.c:2279)
==11465==    by 0x15C4A6: MatchFunction (function.c:1223)
==11465==    by 0x15D8B3: ScanFunctions (function.c:1775)
==11465==    by 0x15967E: FindRest (findpat.c:1133)
==11465==    by 0x1ACE06: TestMatch (pattern.c:346)
==11465==    by 0x1E022D: Generator (proces.c:3964)
==11465==    by 0x1E0A74: Generator (proces.c:4216)
==11465==    by 0x1E2102: Processor (proces.c:406)
==11465==    by 0x150E42: DoExecute (execute.c:858)
==11465==    by 0x17C690: ExecModule (module.c:291)
==11465==    by 0x1D6D57: PreProcessor (pre.c:1041)
==11465==    by 0x21466A: main (startup.c:1690)
==11465==  Address 0x0 is not stack'd, malloc'd or (recently) free'd

[vsht]

You need to escape the comma as

Thanks a lot, this works as expected. Would it make sense to add this piece of information to the manual?

Passing an empty set {} has another issue.

For my purposes using #call proctest({\,0}) as a workaround seems to be good enough. But in general it would be of course nice to fix the empty sets bug.