Hashes have no problem with combining marks. 

$ perl -MData::Dumper -E'
    $Data::Dumper::Useqq = 1;
    $_ = "e\x{301}";
    $h{$_} = 1;
    say $h{$_} || 0;
'
1

[download]

The problem is probably that the character appears both in composed and decomposed form. 

$ perl -E'
    $Data::Dumper::Useqq = 1;
    $a = "e\x{301}";
    $b = "\xE9";
    $h{$a} = 1;
    say $h{$b} || 0;
'
0

[download]

You can use Unicode::Normalize's NFC or NFD to normalize the form. (Doesn't matter which, as long as you're consistent.) 

$ perl -MUnicode::Normalize=NFC -E'
    $Data::Dumper::Useqq = 1;
    $a = NFC("e\x{301}");
    $b = NFC("\xE9");
    $h{$a} = 1;
    say $h{$b} || 0;
'
1

[download]

I'm kinda guessing here since you used 20 lines of code to describe a problem that could be described with 2.

In reply to Re: Unicode combining characters as hash keys? by ikegami
in thread Unicode combining characters as hash keys? by Anonymous Monk

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