Re: append 3 lists in the same time

[Henk Vandecasteele]

Hi,

define:

append_lists([], []).
append_lists([X|Y], Result):-
        ( Y = [] -> Result = X
        ;
          append_lists(Y, TempResult),
          append(X, TempResult, Result)
        ).

Then you can call:

  append_lists([A,B,C], L).

The first argument can have as many elements as wanted. They should all 
be lists of course.

more efficient version, different behaviour when the first argument
is free:

append_lists([], []).
append_lists([X|Y], Result):-
         append_lists2(Y, X, Result).

append_lists2([], X, X).
append_lists2([X|Y], Z, Result):-
        append_lists2(Y, X, TempResult),
        append(Z, TempResult, Result).

Henk


Gurvan Le Guernic wrote:

>     Hi,
> Is there a way to append more than 2 lists in the same time in
> gnu-prolog.
> Like the 'o' in other prolog.
> Example:
> instead of typing: append(A,B,L1), append(L1,C,L).
> we could type something like: L=A o B o C.
>
>
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