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Type testing
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<H3 CLASS="subsection"><A NAME="htoc66">7.1</A> Type testing</H3><UL>
<LI><A HREF="gprolog024.html#toc44"><TT>var/1</TT>,
<TT>nonvar/1</TT>,
<TT>atom/1</TT>,
<TT>integer/1</TT>,
<TT>float/1</TT>,
<TT>number/1</TT>,
<TT>atomic/1</TT>,<BR>
<TT>compound/1</TT>,
<TT>callable/1</TT>,
<TT>list/1</TT>,
<TT>partial_list/1</TT>,
<TT>list_or_partial_list/1</TT></A>
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<A NAME="toc44"></A>
<H4 CLASS="subsubsection"><A NAME="htoc67">7.1.1</A> <TT>var/1</TT>,
<TT>nonvar/1</TT>,
<TT>atom/1</TT>,
<TT>integer/1</TT>,
<TT>float/1</TT>,
<TT>number/1</TT>,
<TT>atomic/1</TT>,<BR>
<TT>compound/1</TT>,
<TT>callable/1</TT>,
<TT>list/1</TT>,
<TT>partial_list/1</TT>,
<TT>list_or_partial_list/1</TT></H4>
<A NAME="var/1"></A>
<B>Templates</B>
<DL CLASS="list" COMPACT="compact"><DT CLASS="dt-list"><DD CLASS="dd-list"><TT>
var(?term)<BR>
nonvar(?term)<BR>
atom(?term)<BR>
integer(?term)<BR>
float(?term)<BR>
number(?term)<BR>
atomic(?term)<BR>
compound(?term)<BR>
callable(?term)<BR>
list(?term)<BR>
partial_list(?term)<BR>
list_or_partial_list(?term)</TT></DL>
<B>Description</B><BR>
<BR>
<TT>var(Term)</TT> succeeds if <TT>Term</TT> is currently
uninstantiated (which therefore has not been bound to anything, except
possibly another uninstantiated variable).<BR>
<BR>
<TT>nonvar(Term)</TT> succeeds if <TT>Term</TT> is currently instantiated
(opposite of <TT>var/1</TT>).<BR>
<BR>
<TT>atom(Term)</TT> succeeds if <TT>Term</TT> is currently instantiated
to an atom.<BR>
<BR>
<TT>integer(Term)</TT> succeeds if <TT>Term</TT> is currently
instantiated to an integer.<BR>
<BR>
<TT>float(Term)</TT> succeeds if <TT>Term</TT> is currently instantiated
to a floating point number.<BR>
<BR>
<TT>number(Term)</TT> succeeds if <TT>Term</TT> is currently instantiated
to an integer or a floating point number.<BR>
<BR>
<TT>atomic(Term)</TT> succeeds if <TT>Term</TT> is currently instantiated
to an atom, an integer or a floating point number.<BR>
<BR>
<TT>compound(Term)</TT> succeeds if <TT>Term</TT> is currently
instantiated to a compound term, i.e. a term of arity > 0 (a list or a
structure).<BR>
<BR>
<TT>callable(Term)</TT> succeeds if <TT>Term</TT> is currently
instantiated to a callable term, i.e. an atom or a compound term.<BR>
<BR>
<TT>list(Term)</TT> succeeds if <TT>Term</TT> is currently instantiated
to a list, i.e. the atom <TT>[]</TT> (empty list) or a term with principal
functor <TT>'.'/2</TT> and with second argument (the tail) a list.<BR>
<BR>
<TT>partial_list(Term)</TT> succeeds if <TT>Term</TT> is currently
instantiated to a partial list, i.e. a variable or a term whose the main
functor is <TT>'.'/2</TT> and the second argument (the tail) is a partial
list.<BR>
<BR>
<TT>list_or_partial_list(Term)</TT> succeeds if <TT>Term</TT> is
currently instantiated to a list or a partial list.<BR>
<BR>
<B>Errors</B><BR>
<BR>
None.<BR>
<BR>
<B>Portability</B><BR>
<BR>
<TT>var/1</TT>, <TT>nonvar/1</TT>, <TT>atom/1</TT>, <TT>integer/1</TT>,
<TT>float/1</TT>, <TT>number/1</TT>, <TT>atomic/1</TT>, <TT>compound/1</TT>
and <TT>callable/1</TT> are ISO predicates.<BR>
<BR>
<TT>list/1</TT>, <TT>partial_list/1</TT> and
<TT>list_or_partial_list/1</TT> are GNU Prolog predicates.<BR>
<BR>
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Copyright (C) 1999-2007 Daniel Diaz
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