Wouldn't in_list be faster if it broke out early, instead of comparing all the items and then coercing to boolean? Something like 
sub in_list { ( $_ eq $_[0] ) && return 1 for @_[ 1 .. $#_ ]; undef;}

[download]
Though personally I'd go with the less compact, but more readable 
sub in_list {
  for (@_[ 1 .. $#_ ]){
    return 1 if $_ eq $_[0];
  }
  undef;
}

[download]
Since if it's going to be a sub anyway, you might as well make it a little easier to read.

In reply to Re: Common Perl Idioms by Eimi Metamorphoumai
in thread Common Perl Idioms by eric256

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