YAP 7.1.0

class fail/0 
fail
defined in the ISO standard
Always fails Defined as if by:
class false/0 
false
defined in the ISO standard
The same as fail Defined as if by:
class true/0 
true
defined in the ISO standard
Succeed
Succeeds once Defined as if by:
class otherwise/0 
otherwise
defined in the ISO standard
Succeed
Succeeds once Defined as if by:
class atom/1 
class atomic/1 
class integer/1 
class number/1 
class primitive/1 
primitive( ?_T_)
Checks whether T is an atomic term or a database reference
class nonvar/1 
class var/1 
class var/2 
?_X_ == ?_Y_
defined in the ISO standard
Succeeds if terms X and Y are strictly identical The difference between this predicate and =/2 is that, if one of the arguments is a free variable, it only succeeds when they have already been unified
fails, but,
succeeds
fails, but,
succeeds
class arg/3 
arg(+ N,+ T, A)
defined in the ISO standard
Succeeds if the argument N of the term T unifies with A The arguments are numbered from 1 to the arity of the term
The current version will generate an error if T or N are unbound, if T is not a compound term, of if N is not a positive integer Note that previous versions of YAP would fail silently under these errors
class functor/3 
functor( T, F, N)
defined in the ISO standard
The top functor of term T is named F and has arity N
When T is not instantiated, F and N must be If N is 0, F must be an atomic symbol, which will be unified with T If N is not 0, then F must be an atom and T becomes instantiated to the most general term having functor F and arity N If T is instantiated to a term then F and N are respectively unified with its top functor name and arity
In the current version of YAP the arity N must be an integer Previous versions allowed evaluable expressions, as long as the expression would evaluate to an integer This feature is not available in the ISO Prolog standard
class current_choice_point/1 
current_choice_point( CP )
unify the logic variable CP with a number that gives the offset of the current choicepoint This number is only valid as long as we do not backtrack by or cut CP, and is safe in the presence of stack shifting and/or garbage collection
Macros  
#define  IN_INLINES_C 1 
Functions  
int  Yap_eq (Term t1, Term t2) 