#!/usr/local/bin/sbcl --script




(defun make-cd (title artist rating ripped)
  (list :title title :artist artist :rating rating :ripped ripped))

(defvar *db* nil)
(defun add-record (cd) (push cd *db*))

(add-record (make-cd "Roses" "Kathy Mattea" 7 t))
(add-record (make-cd "Fly" "Dixie Chicks" 8 t))
(add-record (make-cd "Home" "Dixie Chicks" 9 t))

(defun dump-db ()
  (dolist (cd *db*)
    (format t "~{~a:~10t~a~%~}~%" cd)))

;(dump-db)



;select
(format t "~a~%" "select")



(defun select-by-artist (artist)
  (remove-if-not
   #'(lambda (cd) (equal (getf cd :artist) artist))
   *db*))

(defun select (selector-fn)
  (remove-if-not selector-fn *db*))

(defun artist-selector (artist)
  #'(lambda (cd) (equal (getf cd :artist) artist)))

(format t "~a~%" (select (artist-selector "Dixie Chicks")))



;defmacro
(format t "~a~%" '(1 2 3))
(format t "~a~%" (reverse '(1 2 3)))
(format t "~a~%" "hello, world")
(defmacro backwards (expr) (reverse expr))
(backwards ("hello, world" "~a~%" t format))

(defun make-comparison-expr (field value)
  (list 'equal (list 'getf 'cd field) value))

;(make-comparison-expr :rating 10)
;(make-comparison-expr :title "Give Us a Break")

(format t "~a~%" `(1 2 3))
(format t "~a~%" '(1 2 3))

(format t "~a~%" `(1 2 (+ 1 2)))
(format t "~a~%" `(1 2 ,(+ 1 2)))  

(defun make-comparison-expr (field value)
  `(equal (getf cd ,field) ,value))

(defun make-comparisons-list (fields)
  (loop while fields
     collecting (make-comparison-expr (pop fields) (pop fields))))



(defmacro where (&rest clauses)
  `#'(lambda (cd) (and ,@(make-comparisons-list clauses))))


`(and ,(list 1 2 3))
`(and ,@(list 1 2 3))
`(and ,@(list 1 2 3) 4)


(macroexpand-1 '(where :title "Fly" :ripped t))

;(dump-db)

(format t "~a~%" (select(where :title "Fly" :ripped t)))