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:- module generic_call.

:- interface.

:- type what
    --->    double
    ;       triple.

:- pred alpha(what::in, int::in, int::out) is det.

:- implementation.

:- import_module int.

alpha(What, In0, Out) :-
    force_deps(In0, In),
    (
        What = double,
        Op   = double_int
    ;
        What = triple,
        Op   = triple_int
    ),
    Op(In, Out).

:- pred double_int(int::in, int::out) is det.

double_int(X, X + X).

:- pred triple_int(int::in, int::out) is det.

triple_int(X, X + X + X).

:- pred force_deps(int::in, int::out) is det.

force_deps(!N) :-
    double_int(!N),
    triple_int(!N).