
neg ?Expr

   Expr arithmetically evaluates to 0

Arguments
   Expr                A boolean expression

Type
   library(suspend)

Description
    Suspends until Expr is ground, and then evaluates it. Succeeds if it
    evaluates to 0.

    Typically, the expression contains reifiable constraints, in which case
    a corresponding reified constraint is set up, and the expression is
    replaced by the resulting boolean variable.


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

Fail Conditions
   Expr does not evaluate to 0

Exceptions
    24 --- Expr is not an arithmetic expression.

Examples
   
	?- neg B, B = 1.
	No (0.00s cpu)

	?- neg B, B = 0.
	B = 0
	Yes (0.00s cpu)

	% arguments are typically reifiable expressions:
	?- neg X > 7, X = 8.
	No (0.00s cpu)

	% the previous example is equivalent to:
	?- >(X,7,B), neg B, X=8.
	No (0.00s cpu)

	% and/or/=>/neg are themselves reifiable:
	?- neg(X > 7 or X < 5), X = 7.
	X = 7
	Yes (0.00s cpu)
	

See Also
   neg / 2, and / 2, or / 2, => / 2, ic : neg / 1
