[ Arithmetic | The ECLiPSe Built-In Predicates | Reference Manual | Alphabetic Index ]

+(+Number1, +Number2, -Result)

Evaluates the sum Number1 + Number2 and unifies the resulting value with Result.
A number.
A number.
A variable or a number.


This predicate is used by the ECLiPSe compiler to expand evaluable arithmetic expressions. So the call to +(Number1, Number2, Result) is equivalent to
    Result is Number1 + Number2
which should be preferred for portability.

The result is of type breal if any of the arguments is a breal, else float if any of the arguments is a float, else rational if any of the arguments is a rational. Only when both arguments are integers is the result an integer.

In coroutining mode, if Number1 or Number2 are uninstantiated, the call to +/3 is delayed until these variables are instantiated.

Modes and Determinism


(4) instantiation fault
Number1 or Number2 is not instantiated (non-coroutining mode only).
(5) type error
Result is of a different type than the evaluation result.
(24) number expected
Number1 or Number2 is not of a numeric type.
(24) number expected
Result is neither a number nor a variable.


      +(5, 2, 7).
      +(5, -2.0, 3.0).
      +(1, 2, 7).
      +(A, 2, 6).             (Error 4).
      +(1, 2, 3.0).           (Error 5).
      +(7 - 4, 2, 3).         (Error 24).
      +(5, 2, r).             (Error 24).

See Also

is / 2