How to use predicate transpose in SWI-Prolog?

问题:

Hi guys I want to use predicate transpose(Matrix0, Matrix) in SWI-Prolog which holds when Matrix0 and Matrix are lists of lists, and the “columns” of each are the “rows” of the other. The problem is when I added :- ensure_loaded(library(clpfd)). into my source file and tried to use it, I got this

%    library(occurs) compiled into occurs 0.00 sec, 14 clauses
%   library(apply_macros) compiled into apply_macros 0.00 sec, 44 clauses
%   library(assoc) compiled into assoc 0.00 sec, 103 clauses
ERROR: /Users/Benjamin/Documents/prologworkspace/test.pl:27:
    import/1: No permission to import clpfd:transpose/2 into user (already imported from ugraphs)
%  library(clpfd) compiled into clpfd 0.08 sec, 1,372 clauses
% test compiled 0.08 sec, 1,388 clauses
true.

and I got false when I try this:

?- transpose([['_','_'],['_','_']], X).
false.

Any suggestion? Thank you.

回答1:

import/1: No permission to import clpfd:transpose/2 into user (already imported from ugraphs)

You have a name clash. That's not a problem with the clpfd:transpose/2 itself.

To not import all exported predicates of a module, use

:- use_module(library(clpfd), []).

Then you need to call clpfd:transpose/2 including the name space.

C.f.

• http://www.swi-prolog.org/pldoc/man?predicate=use_module/2
• http://blog.logtalk.org/2009/03/prolog-modules-madness/