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# $::(?Vars, ?Range, ?Bool)

Reified pure range constraint

Vars
  Variable or number, or a list of variables or numbers
Range
  Variable or Lo..Hi, where Lo and Hi are variables or numeric expressions
Bool
  Variable, 0 or 1

## Description

Reified version of $::/2, i.e. the truth value of the range constraint is reflected in the value of the 0/1 variable Bool.

This constraint suspends until its first two arguments are ground. It then unifies Bool according to the truth value of the corresponding $::/2 constraint.

Note: as opposed to $::/2, the first argument cannot be a list.

### Modules

This predicate is sensitive to its module context (tool predicate, see @/2).

## Examples

        ?- $::(X, 1 .. 5, B), X = 3.0.
        B = 1
        X = 3.0
        Yes (0.00s cpu)

        % range violated
        ?- $::(X, 1 .. 5, B), X = 6.
        B = 0
        X = 6
        Yes (0.00s cpu)

## See Also

$:: / 2