The var part can't be an arbitrarily complex expression, as it gets computed for each element of @list: 

perl -E 'say q<Nope> unless grep { $_ eq $c++ } 1..10; say $c'
Nope
10

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In reply to Re^2: Create a new operator, get LHS by Eily
in thread Create a new operator, get LHS by stevieb

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