BinTree-Lisp, Common Lisp

BinTree-Lisp

;gnu clisp  2.49.60

(defun make-bin-tree-leaf (E)
    "Create a leaf"
    (list E))

(defun make-bin-tree-node (E B1 B2)
    "Create a node  with element K, left subtree B1 and right subtree B2"
    (list E B1 B2))

(defun bin-tree-leaf-element (L)
    "Retrieve the element of a leaf L"
    (first L))

(defun bin-tree-node-element (N)
  "Retrieve the element of a node N."
  (first N))

(defun bin-tree-node-left (N)
  "Retrieve the left subtree of a node N."
  (second N))

(defun bin-tree-node-right (N)
  "Retrieve the right subtree of a node N."
  (third N))

(defun bin-tree-leaf-p (B)
  "Test if binary tree B is a leaf."
  (and (listp B) (= (list-length B) 1)))

(defun bin-tree-node-p (B)
  "Test if binary tree B is a node."
  (and (listp B) (= (list-length B) 3)))

(print (make-bin-tree-node '*
                             (make-bin-tree-node '+
                                                 (make-bin-tree-leaf 2)
                                                 (make-bin-tree-leaf 3))
                             (make-bin-tree-node '-
                                                 (make-bin-tree-leaf 7)
                                                 (make-bin-tree-leaf 8))))


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