How to determine the datatype of a variable

Question

It is an easy to answer question (I guess), but I looked for a while not finding anything so I will direct my question to you.

There is the typep to determine whether a given variable is of some specific data-type e.g. integer,hashtable etc. , but is there a function which returns the data-type?

e.g.

(defvar *x* 1)
*x*

(typep *x* 'integer)
T

(the-type-function *x*)
INTEGER

Answer 1

There is the typep to determine whether a given variable is of some specific data-type e.g. integer,hashtable etc. ,

Not really. In Common Lisp variables are not typed as you think.

(defvar *x* 1) *x*  (typep *x* 'integer) T 

Above says nothing about the type of a variable *x*. It confirms that the object 1 is of type integer.

but is there a function which returns the data-type?

Not really. There is a function TYPE-OF, which returns the type of an object, not of a variable.

> (type-of 1) FIXNUM 

There is no difference when we get the value from a variable.

> (type-of *x*) FIXNUM 

But that does not mean the variable has that type.

Note: Common Lisp has types and type declarations. But that looks slightly different.