[mercury-users] define predicate with currying?

[Mark Brown]

Hi Michael,

On 05-Jan-2012, Michael Hendricks <michael at ndrix.org> wrote:
> I have the following simple program:
> 
>     main(!IO) :-
>         hello([s("World")], !IO),
>         hello([s("Mercury")], !IO).
> 
>     :- pred hello(list(string.poly_type)::in, io::di, io::uo).
>     hello(Xs,!IO) :- format("Hello, %s!\n",Xs,!IO).
> 
> Is it possible to define 'hello' by currying 'format'?

No, Mercury doesn't support full currying like Haskell or ML.  The
underlying reason is that, in Mercury, a constant function returning X
is not the same value (or type) as X, so curried definitions would be
ambiguous.

Cheers,
Mark.

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