$_ = q(5              <$> const(PV "{key}") s ->6\n);
/^(.*?<.> )([\w-]+|\S+)(.*?)$/ or next

# $1 == 19
# $2 eq "const"
# $3 eq '(PV "{key}") s ->6\n'

# Matching against $3
my $pv = ( $3 =~ /[INP]V ("?(?:\\"|[^"])*"?)/ )[0];

# Or matching against a variable and then assigning into it.
my $pv = $3;
$pv = ( $pv =~ /[INP]V ("?(?:\\"|[^"])*"?)/ )[0];