;;;; decons

(defpackage :decons
  (:use :common-lisp)
  (:local-nicknames (:util :scopes/util))
  (:export #:*pi* #:area #:circle
           #:absv #:double #:remainder
           #:scalar-p #:tensor #:at
           #:line
           ))

(in-package :decons)

;;;; basic explorations

(defconstant *pi* 3.14159)

(defclass circle ()
  ;;; ! implement as closure
  ((radius :accessor radius :initarg :radius :initform 1)))

(defgeneric area (c)
  (:method ((c circle))
    (* *pi* (radius c) (radius c))))

(defun double (f) 
  #'(lambda (v) (* 2 (funcall f v))))

(defun absv (v)
  (if (< v 0) (- v) v))

(defun remainder (v d)
  (if (< v d) 
    v
    (remainder (- v d) d)))

;;;; library stuff

(defgeneric scalar-p (x)
  (:method (x) t)
  (:method ((x list)) nil)
  (:method ((x array)) nil))

(defun tensor (s v)
  (make-array s :initial-contents v))

(defun at (a &rest subs)
  (apply #'aref a subs))

(defun (setf at) (v a &rest subs)
  (setf (apply #'aref a subs) v))

;;;; parameterized functions

(defun line (x)
  #'(lambda (theta) (+ (cadr theta) (* (car theta) x))))