Presuming elements of @a1 are unique . . . 

my %a1_indexen;
@a1_index{ @a1 } = 0..$#a1;

my @indexen = map $a1_index{ $_ }, @a2;

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The cake is a lie.
The cake is a lie.
The cake is a lie.

In reply to Re: Scanning a list for indices by Fletch
in thread Scanning a list for indices by cmv

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