[eclipse-clp-users] Looking for builtin variant of is/2 that suspends on Expr2

Is there a builtin that does assignment like is/2 but suspends on the second
parameter? (Another way of looking at it is that I'm looking for a variant
of $= that does not suspend on Expr1 but instead does assignment once Expr2
is bound.)

This seems like a very common need, but I can't find it in the list of
builtins, nor in the similar predicates listed at the bottom of the pages
about $=, =:=, is/2, etc.