Simplified Common Lisp reference
Symbol class: Symbol, Characters, Hash, Structure, Objects and Conversions
Symbol type: function
make-hash-tabletest(keyword)size(keyword)rehash-size(keyword)rehash-threshold(keyword) => hash-table
Argument description:
test EQ, EQL EQUAL or EQUALP; default is EQL
size a non-negative integer
rehash-size a real number
rehash-threshold a real number

MAKE-HASH-TABLE creates a new hash-table. Size parameter specifies initial size of inner table. Test specifies comparison operator for keys. See also GETHASH.

(defparameter *tab* (make-hash-table)) => *TAB*
(gethash 'x *tab*) => NIL, NIL
(setf (gethash 'x *tab*) "x") => "x"
(setf (gethash 'y *tab*) "yy") => "yy"
(gethash 'x *tab*) => "x", T
(gethash 'y *tab*) => "yy", T
(gethash 'z *tab* 'moo) => MOO, NIL
Function indexFull documentation for make-hash-table (HyperSpec)