impure_method_impl.m:025: Warning: the type class `impure_method_impl.c'/1 and
impure_method_impl.m:025:   the type constructor in the argument vector of this
impure_method_impl.m:025:   instance declaration for it, namely
impure_method_impl.m:025:   `impure_method_impl.foo'/0, are all visible outside
impure_method_impl.m:025:   this module, which means that this instance can be
impure_method_impl.m:025:   relevant outside this module. Keeping it private to
impure_method_impl.m:025:   this module is therefore likely to be a mistake.
impure_method_impl.m:026: Error: instance method predicate `m1'/2 is semipure.
impure_method_impl.m:026:   It must either be declared semipure, or promised
impure_method_impl.m:026:   pure.
impure_method_impl.m:026: In call to semipure predicate
impure_method_impl.m:026:   `impure_method_impl.foo_m1'/2:
impure_method_impl.m:026:   purity error: call must be preceded by a `semipure'
impure_method_impl.m:026:   indicator.
impure_method_impl.m:027: Error: instance method predicate `m2'/2 is impure. It
impure_method_impl.m:027:   must either be declared impure, or promised
impure_method_impl.m:027:   semipure.
impure_method_impl.m:027: In call to impure predicate
impure_method_impl.m:027:   `impure_method_impl.foo_m2'/2:
impure_method_impl.m:027:   purity error: call must be preceded by an `impure'
impure_method_impl.m:027:   indicator.