There are two assignment operator.

• The scalar assignment operator imposes scalar context on both of its operands.
• The list assignment operator imposes list context on both of its operands.

The choice of which assignment operator is used is based on what syntax of its LHS operand. If it "looks like a list", the list assignment operator will be used.

(my $first_entry) = grep ...;
my ($first_entry) = grep ...;
my @entries = grep ...;
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Related: Mini-Tutorial: Scalar vs List Assignment Operator.