Re: Flatten, question

Thank you very much for your hint, great!
Hartmut

Lindsey Spratt wrote:
> Use append(FlatHead, FlatTail, List) instead of concat(...).
> 
> concat/3 is for combining atoms to create a new atom. append/3 is for 
> appending lists to create a new list: more generally it is true if the 
> third argument is the list that is the second argument list appended to 
> the first argument list.
> 
> Lindsey
> 
> On Oct 30, 2008, at 2:13 PM, Hartmut Lange wrote:
> 
>> Everybody,
>> is somebody here who can help me in this small algorithm.
>> Why do I get
>>  atom_concat/3: Type error: `atomic' expected, found `[g]'
>>  atom_concat/3: Type error: `atomic' expected, found `[e]'
>> in the line where flatten1(...) is called with the list of a,b,c...
>> What's wrong with that... hmm? I found it in the Prolog book of 
>> Bratko, excercise 3.11
>> I am using SWI-Prolog 5.6
>> Regards,
>>
>>
>> flatten1([Head|Tail], List) :-
>>    flatten1(Head, FlatHead),
>>    flatten1(Tail, FlatTail),
>>    concat(FlatHead,FlatTail, List).
>>
>> flatten1([], []).
>> flatten1(X, [X]).
>>
>> :- flatten1([a,b,c,e,f,g], List),
>>   write('Flat List:'), write(List).
>>
>> :- flatten1([a,b,[c,e],f,g], List),
>>   write('Flat List:'), write(List).
>>
>>
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