- 
          Peter Dimov suggested the name 'optional', and was the first to point out
          the need for aligned storage.
        
- 
          Douglas Gregor developed 'type_with_alignment', and later Eric Friedman
          coded 'aligned_storage', which are the core of the optional class implementation.
        
- 
          Andrei Alexandrescu and Brian Parker also worked with aligned storage techniques
          and their work influenced the current implementation.
        
- 
          Gennadiy Rozental made extensive and important comments which shaped the
          design.
        
- 
          Vesa Karvonen and Douglas Gregor made quite useful comparisons between
          optional, variant and any; and made other relevant comments.
        
- 
          Douglas Gregor and Peter Dimov commented on comparisons and evaluation
          in boolean contexts.
        
- 
          Eric Friedman helped understand the issues involved with aligned storage,
          move/copy operations and exception safety.
        
- 
          Many others have participated with useful comments: Aleksey Gurotov, Kevlin
          Henney, David Abrahams, and others I can't recall.
        
- 
          William Kempf carefully considered the originally proposed interface and
          suggested the new interface which is currently used. He also started and
          fueled the discussion about the analogy optional<>/smart pointer
          and about relational operators.
        
- 
          Peter Dimov, Joel de Guzman, David Abrahams, Tanton Gibbs and Ian Hanson
          focused on the relational semantics of optional (originally undefined);
          concluding with the fact that the pointer-like interface doesn't make it
          a pointer so it shall have deep relational operators.
        
- 
          Augustus Saunders also explored the different relational semantics between
          optional<> and a pointer and developed the OptionalPointee concept
          as an aid against potential conflicts on generic code.
        
- 
          Joel de Guzman noticed that optional<> can be seen as an API on top
          of variant<T,nil_t>.
        
- 
          Dave Gomboc explained the meaning and usage of the Haskell analog to optional<>:
          the Maybe type constructor (analogy originally pointed out by David Sankel).
        
- 
          Other comments were posted by Vincent Finn, Anthony Williams, Ed Brey,
          Rob Stewart, and others.
        
- 
          Joel de Guzman made the case for the support of references and helped with
          the proper semantics.
        
- 
          Mat Marcus shown the virtues of a value-oriented interface, influencing
          the current design, and contributed the idea of "none".