
+(+Number, -Result)

   Checks if Number is a number and unifies it with Result.



Arguments
   Number              A number.
   Result              A variable or a number.

Type
   Arithmetic

Description
   This predicate is used by the ECLiPSe compiler to expand evaluable
   arithmetic expressions.  So the call to +(Number, Result) is equivalent
   to

    Result is +Number

    which should be preferred for portability.

   Number and Result have to be of the same type.


   In coroutining mode, if Number is uninstantiated, the call to +/2 is
   delayed until this variable is instantiated.




Modes and Determinism
   +(+, -) is det

Exceptions
     4 --- Number is not instantiated (non-coroutining mode only).
     5 --- Result and Number are numbers of different types.
    24 --- Number is not of a numeric type.
    24 --- Result is neither a number nor a variable.

Examples
   
Success:
      +(1, 1).
      +(5, Result).        (gives Result = 5)
      +(-6.2, Result).     (gives Result = -6.2)
Fail:
      +(1, 0).
Error:
      +(A, 6).                   (Error 4).
      +(1.0, 1).                 (Error 5).
      +(1, 1.0).                 (Error 5).
      +(4 + 2, 6).               (Error 24).
      +(1, r).                   (Error 24).





See Also
   is / 2
