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# +(+Number, -Result)

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

Number
  A number.
Result
  Output: 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.

Result is identical to Number.

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) instantiation fault
  Number is not instantiated (non-coroutining mode only).
(24) number expected
  Number is not of a numeric type.

## Examples

    Success:
        Result is + 1.		% gives Result = 1
        Result is + 5.        	% gives Result = 5
        Result is + -6.2.     	% gives Result = -6.2

        Result is +(1).		% gives Result = 1
        Result is +(5).        	% gives Result = 5
        Result is +(-6.2).     	% gives Result = -6.2

## See Also

is / 2