that's very different because there are no lines in between.

use strict;
use warnings;
use Test::More;

my $in = 'A |simple*example| is |so*simple| to come*up |with
these*days| according to some *experts*';

my $exp = 'A |simple-example| is |so-simple| to come*up |with
these-days| according to some *experts*';

my $start = qr/\|/;
my $stop  = qr/\|/;

my $got = $in;

$got =~
s[
     ($start) (.*?) ($stop)
][
   "$1"
   . ( $2 =~ tr/\*/-/r )
   . "$3"
 ]gsxe;

is($got,$exp);

done_testing;
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updates

added

• test
• line-break