Re: [boost] Interest in an 'either' library?

On 06/21/13 11:35, David Sankel wrote:

**semantics**:

template< typename left_type, typename right_type> struct either { // postcondition, is_left() either( left_type );

// postcondition, is_right() either( right_type );

bool is_left() const; bool is_right() const;

// postcondition, is_left() either & operator=( left_type );

// postcondition, is_right() either & operator=( right_type );

// precondition, is_left() left_type left();

// precondition, is_right() right_type right(); private: };

**uses**:

**Use 1**: Can be used as an alternative to exceptions or the (error codes+set reference idiom):

either load_file(...);

vs.

error_code load_file( file_id &, ... );

or

// throws std::exception file_id load_file(...);

Isn't this like haskell's either: http://www.haskell.org/ghc/docs/6.12.2/html/libraries/base-4.2.0.1/Data-Eith... which also has been suggested as a semi-replacement for exceptions: http://www.haskell.org/pipermail/haskell-cafe/2004-August/006549.html which uses the terms expected and unexpected, which might explain the name expected used in the proposed Boost.Expected library mentioned in Bjorn Reese's reply. I remember seeing elsewhere that haskell's either was mentioned as a replacement for exceptions. I see if I can find it. -regards, Larry