as_goal.clj

;; As a goal

;; Non-relational
;; Accepts these patterns of arguments:
;; IOO
;; III
;; IOI
;; IIO

;; I=input (ground), O=output (not ground)

(defn items-colors-for-country [country item-name item-color]
  (fresh [not-country]
    (items item-name item-color)
    (!= country not-country)

    (conda
      [(restricted-to country item-name)
       (conda
         [(not-allowed-in country item-name)
          fail]
         [succeed])]
      [(restricted-to not-country item-name)
       fail]
      ;; No entry in restricted-to for item-name
      [(not-allowed-in country item-name)
       fail]
      [succeed])))

(run* [q]
  (fresh [country item-name item-color]
    (== q [country item-name item-color])
    (conde
      [(== 'US country)]
      [(== 'UK country)]
      [(== 'France country)]
      [(== 'Australia country)])
    (items-colors-for-country country item-name item-color)))
;=> ([US Purse Blue] [UK Purse Blue] [US Banana Yellow] [US Car Red] [Australia Purse Blue] [Australia Banana Yellow] [France Banana Yellow])

(run* [q]
  (fresh [country item-name item-color]
    (== q [country item-name item-color])
    (== item-color 'Blue)
    (conde
      [(== 'US country)]
      [(== 'UK country)]
      [(== 'France country)]
      [(== 'Australia country)])
    (items-colors-for-country country item-name item-color)))
;=> ([US Purse Blue] [UK Purse Blue] [Australia Purse Blue])