Hello asqwerty, and welcome to the Monastery!

You already have the answer you were looking for. I just want to point out that the line:

%dfs = map {$_ => ()} @pref;

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is incorrect. You can see this by printing the contents of %dfs (using Data::Dumper) immediately after that line:

$VAR1 = {
          'brain' => 'lung',
          'kidney' => undef
        };

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When interpolated into an array or hash, the empty list () effectively disappears. I think you meant to write:

%dfs = map {$_ => []} @pref;

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which works correctly, although

%dfs = map {$_ => undef} @pref;

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also works.

Here is some good advice: Get into the habit of including the lines

use strict;
use warnings;

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at the head of every script. In this case, warnings would have shown you the problem:

Odd number of elements in hash assignment at ... line 6.

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Hope that helps,

Athanasius <°(((>< contra mundum

In reply to Re: populating a HoA with regexp by Athanasius
in thread populating a HoA with regexp by asqwerty

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