what does the parser think the modulo and number is doing there?

It thinks you made a weird coding choice, which is why perl will warn you about it, if you let it:

C:\> perl -Mbignum -le  "use warnings; use strict; print ( 7 ** 127 ) 
+% ( 524287 )"
print (...) interpreted as function at -e line 1.
Useless use of modulus (%) in void context at -e line 1.
2125450924568016708443303831058962243331938167363998499854997578694839
+02203328714236393937418376186556719543
[download]

Yet another reason to always use warnings; use strict; or equivalent.

++ I'm a little late to the party on this one: I've been tied up with other things over the last few days. I was going to mention warnings but, as I see you've already done this, here's some additional information for the AM.

You're using v5.36.1. If you specify use v5.36 you'll automatically get strict and warnings.

$ perl -e 'use warnings; print (7 + 1)'
print (...) interpreted as function at -e line 1.
8

$ perl -e 'use v5.36; print (7 + 1)'
print (...) interpreted as function at -e line 1.
8

$ perl -e 'use v5.36; print +(7 + 1)'
8
[download]

[See "perl5360delta: use v5.36" for other things you'll get automatically.]

See in perldiag, "%s (...) interpreted as function". You can get that warning with many functions, not just print.

See in perlop, "Symbolic Unary Operators" (penultimate paragraph)

'Unary "+" ... It is useful syntactically for separating a function name from a parenthesized expression that would otherwise be interpreted as the complete list of function arguments. ...' [my emphasis]

— Ken

... from my trial and error it seems [the parser is] trying to do modulo using the return value of print function ( = "1" ) ...

Perl can tell you with perfect clarity (update: and lots of parentheses) exactly how it sees the syntax it's trying to compile. See core modules O and B.

Win8 Strawberry 5.8.9.5 (32)  Tue 07/04/2023 15:01:58
C:\@Work\Perl\monks
>perl  -wMstrict  -MO=Deparse,-p  -le  "print (5+6) + (6*7) + (7**8);"
print (...) interpreted as function at -e line 1.
Useless use of addition (+) in void context at -e line 1.
BEGIN { $^W = 1; }
BEGIN { $/ = "\n"; $\ = "\n"; }
use strict 'refs';
((print(11) + 42) + 5764801);
-e syntax OK

>perl  -wMstrict  -MO=Deparse,-p  -le  "print +(5+6) + (6*7) + (7**8);
+"
BEGIN { $^W = 1; }
BEGIN { $/ = "\n"; $\ = "\n"; }
use strict 'refs';
print(5764854);
-e syntax OK


Win8 Strawberry 5.30.3.1 (64)  Tue 07/04/2023 15:03:46
C:\@Work\Perl\monks
>perl  -wMstrict  -MO=Deparse,-p  -le  "print (5+6) + (6*7) + (7**8);"
print (...) interpreted as function at -e line 1.
Useless use of addition (+) in void context at -e line 1.
BEGIN { $^W = 1; }
BEGIN { $/ = "\n"; $\ = "\n"; }
use strict;
((print(11) + 42) + 5764801);
-e syntax OK

>perl  -wMstrict  -MO=Deparse,-p  -le  "print +(5+6) + (6*7) + (7**8);
+"
BEGIN { $^W = 1; }
BEGIN { $/ = "\n"; $\ = "\n"; }
use strict;
print(5764854);
-e syntax OK
[download]

echo " python3.11.4 :: $( python3 -c 'print(  ( 2**3 - 1 )**( 2**7 - 1
+ ) % ( 2**19 - 1 ) )' )"
echo " perl 5.36 :: $( perl -Mbignum -le 'print ( 2**3 - 1 )**( 2**7 -
+ 1 ) % ( 2**19 - 1 )' )"
echo " gawk 5.2.2 :: $( gawk -p- -Mbe 'BEGIN { print ( ( 2^3 - 1 ) ^ (
+ 2^7 - 1 ) ) % ( 2 ^ 19 - 1 ) }' )"

 python3.11.4 :: 102010
 perl 5.36 :: 7
 gawk 5.2.2 :: 102010

    # gawk profile, created Mon Jul  3 16:24:54 2023

    # BEGIN rule(s)

    BEGIN {
     1      print ((2 ^ 3 - 1) ^ (2 ^ 7 - 1)) % (2 ^ 19 - 1)
    }
[download]

I see you haven't read perlfunc yet.


print ( 2**3 - 1 )**( 2**7 - 1 ) % ( 2**19 - 1 )
[download]

is equivalent to

( print ( 2**3 - 1 ) )**( 2**7 - 1 ) % ( 2**19 - 1 )
[download]

and not the

print( ( 2**3 - 1 )**( 2**7 - 1 ) % ( 2**19 - 1 ) )
[download]

that you think it is.

That's why I put a + before the first parenthesis - it's one of the few times where a unary + is highly significant.

UPDATE: added the word "unary"