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% vim: ts=4 sw=4 et ft=mercury
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:- module constraint_proof_bug.

:- interface.

:- import_module io.

:- pred main(io::di, io::uo) is det.

:- implementation.

:- import_module constraint_proof_bug_lib.
:- import_module io.
:- import_module require.
:- import_module string.

:- type service == string.
:- type prestationid == int.
:- type provider == int.

:- type bevent
    --->    prest(prestationid, date, code, provider)
    ;       day(int, date)
    ;       admit(date, service)
    ;       discharge(date, service)
    ;       transfer(date, service, service)
    ;       wrong(date).

:- some [T] pred get_field(bevent, string, T) => constrainable(T).
:- mode get_field(in, in, out) is semidet.

get_field(Ev, Field, R) :-
    ( if Field = "date" then
        R = d(Dt),
        get_date_field(Ev, Dt)
    else if Field = "code" then
        R = c(Cd),
        get_code_field(Ev, Cd)
    else
        error("No handler for this field")
    ).

:- pred get_date_field(bevent::in, date::out) is det.

get_date_field(prest(_, Dt, _, _), Dt).
get_date_field(day(_, Dt), Dt).
get_date_field(admit(Dt, _), Dt).
get_date_field(discharge(Dt, _), Dt).
get_date_field(transfer(Dt, _, _), Dt).
get_date_field(wrong(Dt), Dt).

:- pred get_code_field(bevent::in, code::out) is semidet.

get_code_field(prest(_, _, Cd, _), Cd).

main(!IO) :-
    io.print("hello world\n", !IO).