The possible values for InfoName are type or name.
If InfoName unifies with name, the predicate will succeed if the source name of the free variable Var is available and unifies with Value.
If InfoName unifies with type, the predicate will succeed if Value unifies with the type of the variable Var.
The possible types are:
meta an attributed variable (metaterm)
free a free variable
Success:
?- suspend:(Var1 > Var2), get_var_info(Var1, Info, Value).
Var2 = Var2
Var1 = Var1
Info = name
Value = 'Var1'
Delayed goals:
Var1 > Var2 More? (;)
Var2 = Var2
Var1 = Var1
Info = type
Value = meta
Delayed goals:
Var1 > Var2
yes.
?- get_var_info(Var1, type, Type).
Var1 = Var1
Type = free
yes.
?- set_flag(variable_names,off).
yes.
?- get_var_info(Var1, name, Name).
no (more) solution.
Fail:
get_var_info(atom, name, Name).
set_flag(variable_names, off),
get_var_info(X, name, Name).
Error:
get_var_info(X, not_an_info, Y). (Error 6)
get_var_info(X, type, 123). (Error 5)