How to find unexpected choicepoints?

Help!
14

It would be nice to have a library of predicate assert-checking:

:- expect_det(p/a).              
:- expect_true(p/a).               % This predicate should never be false.
:- expect_number(p/a, 2).     % arg2 should be a number
:- expect_grounded(p/a, 2).   % arg2 should always be grounded   
....

Or better, have these assumptions formally (and optionally) part of the language syntax:

p(X:grounded, Y:number) : det, true  :-
    ...

or, perhaps just:

:- constraints( p(grounded, number), [det, true] )
    ...

Do such tools exist?

Mercury has something similar, but I think it breaks compatibility with standard Prolog, which is a shame.