Re: [eclipse-clp-users] List of Terms to Term

From: Kish Shen <kisshen_at_...5...>
Date: Tue, 23 Feb 2010 18:41:26 +0000
Christian Wirth wrote:
> Kish Shen schrieb:
>> Christian Wirth wrote:
>>
>>> i want to convert a list of terms into a term:
>>>
>> I am not clear what you mean by this: a list of terms *is* a term itself.
> Not every list, only when its correctly nested. I simply have a list 
> where each element is a term: [pred(A,B),pred2(A,C),pred3(B,C)] is not a 
> correct term, but a list of terms (, is the element seperation symbol, 
> not the AND symbol)
> 

There seem to be some misunderstanding here. Are you under the 
impression that a list is not a term? This is not correct. In fact, any 
valid Prolog data structure is a term, so, I repeat, a list of terms is 
by definition a term itself. Do you by any chance mean a structure 
rather than a term? Even in this case, list are actually structures -- 
nested ./2 structures, but because they occur so often, Prolog provide 
special syntax that lets you write them more easily. This is discussed 
in any introductory Prolog textbook.


> The problem i have is, i need to call \+(\+(List)) .. but i get an 
> error:  type error in existing_file([d_role(Player, state), 'd_++'(_403, 
> _478, state), 'd_++'(_403, _478, state), d_cell(_402, _478, state)], 
> [".eco", "", ".ecl", ".pl"], [readable], _786)
>

\+ \+ (List) does not make sense -- the argument of \+/1 should be a 
goal, not any data structure. In this case, your list is being treated 
as a list of files to be compiled.

Cheers,

Kish


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Received on Tue Feb 23 2010 - 18:41:33 CET

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