http://www.perlmonks.org?node_id=709290


in reply to Benchmarking "Are all these characters in this sentence?"

Just for completeness, try this one, too: 
  martin => sub {
      # args: sentence, wantedchars
      '' eq $_[1] ||
      '' ne $_[0] &&
      $_[1] =~ /^[\Q$_[0]\E]*\z/;
  },

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Putting the whole sentence into a character class will kind of suck with veeery long sentences but medium-sized cases should benefit from the one-pass approach.

Update: fixed the order of subroutine parameters

In Section Meditations