Two-way phone call: Phone Bool dialing, two-way call.
Bool: these are the true or false.
Called to implement truth value testing and
the built-in operation Bool();
Bool- This represents a Boolean value which is either true or false.
Type of variable. Use"Bool" for a Boolean, otherwise it is treated as a string.
the function would have the type''a× ''a list → Bool and''a can only be a
In general, Java has primitive types(int, Bool, char, double, etc) that are passed directly by value.
If neither __len__() nor __Bool__() are defined by a class then all its instances are considered to be True.
Also, an object that doesn't define a __Bool__() method and whose __len__()
method returns zero is considered to be false in a Boolean context.
By default,
an object is considered true unless its class defines either a __Bool__() method that returns False or a __len__()
method that returns zero, when called with the object.
In Standard ML, type parameters of the form''a are restricted so that the equality operation is available, thus
the function would have the type''a× ''a list → Bool and''a can only be a
type with defined equality.