
term_variables(?Term, -VarList)

   Succeeds if VarList is the list of all variables in Term.

Arguments
   Term                Prolog term.
   VarList             List or variable.

Type
   Term Manipulation

Description

   This predicate collects all the variables inside Term into the list
   VarList.  Every variable occurs only once in VarList, even if it occurs
   several times in Term.  The order of the variables in the list is not
   specified.

   As usual, attributed variables are also considered variables.

   This predicate terminates even with cyclic terms.



Modes and Determinism
   term_variables(?, -) is det

Exceptions
     5 --- VarList instantiated but not to a list.

Examples
   
Success:
    term_variables(atom, []).
    term_variables(Term, Vs).       % gives Vs = [Term]
    term_variables(f(a,B,c), Vs).   % gives Vs = [B]
    term_variables([X,Y,Z], Vs).    % gives Vs = [Z,Y,X]
    term_variables([X,Y,X], Vs).    % gives Vs = [Y,X]
    term_variables(s(X{a}), Vs).    % gives Vs = [X{a}]

Fail:
    term_variables(f(a,B,c), []).


See Also
   term_variables_array / 2, nonground / 1, nonground / 2, nonground / 3, nonvar / 1, var / 1
