;; see OnLisp, Chp. 19.

;;(defvar hash (make-table string-hash #'equal)) ; hash-fun compare-fun
;;;; make-weak-table: members are subject to garbage collection
;;(table-set hash "aap" "noot")
;;(table-set hash "mies" "wim")
;;(table-set hash "zus" "jet")
;;(table-set hash "teun" "vuur")
;;(puts (table-ref hash "aap"))              ; noot
;;(puts (table-bound-p hash "mies"))         ; t
;;(table-unset hash "teun")                  ; remove entry
;;(table-walk
;; (lambda (key value)
;;   (printf "%s -> %s\n" key value))
;; hash)

(require 'rep.data.tables)

(defun make-db ()
  (make-table symbol-hash #'equal))

(defvar *default-db* (make-db))

(defmacro db-query (key)
  `(table-ref ,*default-db* ,key))

(defun db-push (key val)
  (table-set *default-db* key val))

(defmacro fact (pred #!rest args)
  `(progn (db-push ',pred ',args)
          ',args))

;; XXX incomplete and incorrect