Sorry Limbic~Region, I got carried away with your "Only modify this line" (and had a brainfart too!).

There is no point in looping over the array, that's why we put in a hash. It should have looked something like this. 

my @list = ...;
my %list; @list{ map{ substr $_, 0, 1 } @list } = ();

my $str_a = 'Foo';                               
expensive_function($str_a , $str_b) 
    unless exists $list{ substr $str_a, 0, 1 };

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Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"Think for yourself!" - Abigail

In reply to Re: Re: Re: Matching First Character of Strings Efficiently by BrowserUk
in thread Matching First Character of Strings Efficiently by Limbic~Region

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