The quotes are necessary here for variable interpolation which, according to The Camel(sec. ed.), is "really just a handy form of string concatenation". Try this instead:

my $gah = join ("<br>", map {'$_ = $somehash{$_}'} keys %somehash);
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Big difference. Generally, double quoting scalars is a Bad Idea only if it is "useless". I see a lot of newbies trying silly things like:

my $first = "Hello World\n";
my $second = "$first";
print "$second";
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Only the first set of double quotes are necessary for the special character "\n". So ,what harm is done with that example? None, but this behaviour usually stems from Cargo Cult Programming, and that's why it's a Bad Idea. Double quotes are good when used responsibly. Irresponsible use will lead to mistakes like thinking that an object ref is a scalar:

use strict;
use CGI;

my $q = CGI->new();

print "$q->param('foo')\n";     # wrong
print $q->param('foo'),"\n";    # right
print $q->param('foo')."\n";    # right
print "@{[$q->param('foo')]}\n" # right, but twisted ;)
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jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)