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A constraint is called as any other Prolog predicate. When called, the
constraint is *posted* to the store. For example:

| ?-X in 1..5, Y in 2..8, X+Y #= T.X in 1..5, Y in 2..8, T in 3..13 | ?-X in 1..5, T in 3..13, X+Y #= T.X in 1..5, T in 3..13, Y in -2..12

Note that the answer constraint shows the domains of nonground query variables, but does not show any constraints that may be attached to them.

Normally, after posting a constraint, propagation to fixpoint is performed, which can be an overkill. The following provides a means of posting a set of constraints in one batch, suspending all propagation until the whole set has been posted. Suspending propagation can significantly reduce posting overhead.

`fd_batch(`

`+Constraints`)*since release 4.2.1*-
where

`Constraints`should be a list of constraints, user-defined or exported by`library(clpfd)`

. General Prolog goals among the constraints will have undefined behavior.

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