% vim: ts=4 ft=mercury et
% rotd-2009-02-17 reports an error message for the following.
%
% inst_subtype_exists.m:045: In clause for
%   `print_result(in((inst_subtype_exists.cannot_fail)),
%   di, uo)':
%   mode error in unification of `Result' and
%   `inst_subtype_exists.exception(TypeInfo_15, V_7)'.
%   Variable `Result' has instantiatedness
%   `bound(inst_subtype_exists.exception(ground) ;
%   inst_subtype_exists.succeeded(ground))',
%   term `inst_subtype_exists.exception(TypeInfo_15,
%   V_7)' has instantiatedness
%   `inst_subtype_exists.exception(
%     free,
%     free
%   )'.
%
% The mode analyser appears to be including the introduced
% type-infos in the insts it infers for existentially quantified
% data constructors.

:- module inst_subtype_exists.
:- interface.

:- import_module io.

:- type exception_result(T)
    --->    succeeded(T)
    ;       failed
    ;       some [E] exception(E).


:- inst cannot_fail
    --->    succeeded(ground)
    ;       exception(ground).

:- pred print_result(exception_result(T)::in(cannot_fail), io::di, io::uo)
    is det.

:- implementation.

print_result(Result, !IO) :-
    (
        Result = succeeded(R),
        io.write(R, !IO)
    ;
        Result = exception(_),
        io.write_string("exception", !IO)
    ).