(defpackage :the-type
   (:use :cl))
 (in-package :the-type)
 

 (defclass binding ()
   ((%type :initarg :type :accessor type-binding)
    (%value :initarg :value :accessor value-binding)))
 

 (defclass environment ()
   ((%vars :initarg :vars :initform (make-hash-table))

    (%funcs :initarg :funcs :initform (make-hash-table))))
 
 (defparameter *the-env* (make-instance 'environment))
 
 (defmacro define-function-binding (name env (&key return-type) (&rest args) &body body)
   `(setf (gethash ',name (funcs ,env)
                   )))
 
 (progn
   (setf (gethash '+ (funcs *the-env*))
         #'+)
   (setf (gethash '+ (funcs *the-env*))
         #'+)
   )

 (defun annotate-function-call (function-type call-form)
   (mapcar (lambda (type-element call-element)
             (list type-element call-element))
           function-type call-form))

 (defun check-function-type (function args)
   (let ((type-sig (case function
                     ('+ '(number number))
                     ('* '(number number))
                     ('length '(string)))))
     (when (= (length type-sig) (length args))
       )))
 (defun check-types (form)
   (typecase form
     (cons (check-function-type (car form) (cdr form)))
     (t t)))