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+(+Number, -Result)

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

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

Exceptions

(4) instantiation fault
Number is not instantiated (non-coroutining mode only).
(5) type error
Result and Number are numbers of different types.
(24) number expected
Number is not of a numeric type.
(24) number expected
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