Declare optional types which are checked during development time. See pack documentation for more information.

 the(+Type:type, ?Value) is det

Declare that Value has the given Type. Succeeds if Value is bound to a value that's compatible with Type. Throws an informative exception if Value is bound to a value that's not compatible with Type. If Value is not bound, the type check is delayed until Value becomes ground.

When optimizations are enabled (current_prolog_flag(optimise, true)) a macro removes the entirely so that it always succeeds.

 type_subtype(?Type, ?Subtype)[multifile]

Multifile predicate for declaring that a Type has a Subtype. It should only be necessary to add clauses to this predicate if has_subtype/2 has trouble deriving this information based on your definition of arbitrary/2.

 has_subtype(+Type, +Subtype) is semidet

True if all values of Subtype are also values of Type. This can be used to determine whether arguments of one type can be passed to a predicate which demands arguments of another type.

This predicate performs probabilistic subtype detection by leveraging your definitions for error:has_type/2 and arbitrary/2. If this predicate is not detecting your types correctly, either improve your arbitrary/2 definition or add clauses to the multifile predicate type_subtype/2.

 type_intersection(?Type, ?IntersectionType)[multifile]

Multifile predicate for declaring that Type has an IntersectionType. See type_subtype/2 for further details.

 has_intersection(Type, IntersectionType) is semidet

True if some value of IntersectionType is also of Type. See has_subtype/2 for further details.

 known_type(?Type:type) is semidet

True if Type is a type known to error:has_type/2. Iterates all known types on backtracking. Be aware that some types are polymorphic (like list(T)) so Type may be a non-ground term.

As a convenience, the type named type describes the set of all values for which known_type/1 is true.

Undocumented predicates

The following predicates are exported, but not or incorrectly documented.

 build_type_assertions(Arg1, Arg2, Arg3)

 build_determinism_assertions(Arg1, Arg2)

 run_goal_at_mode(Arg1, Arg2, Arg3, Arg4)