boolcascalog.clj

(deffilterop [always-true [some-bool]]
  [x]
  (or some-bool true))

(?<- (stdout)
     [?value]
     ([[1]] ?value)
     (always-true [true] ?value))

RESULTS
-----------------------
1	true
-----------------------

(?<- (stdout)
     [?value ?bool]
     ([[1]] ?value)
     (always-true [false] ?value :> ?bool))

RESULTS
-----------------------
1	false
-----------------------

(?<- (stdout)
     [?value ?bool]
     ([[1]] ?value)
     (always-true [nil] ?value :> ?bool))

RESULTS
-----------------------
1	true
-----------------------

;; defmapcatop deals with this just fine

(defmapcatop [always-returns [some-bool]]
  [x]
  (when (or some-bool true)
    [x]))

(?<- (stdout)
     [?ret]
     ([[1]] ?value)
     (always-returns [false] ?value :> ?ret))

RESULTS
-----------------------
1
-----------------------

(?<- (stdout)
     [?ret]
     ([[1]] ?value)
     (always-returns [true] ?value :> ?ret))

RESULTS
-----------------------
1
-----------------------

;; More funky stuff -- that println prints "false? true", which is what we want.
;; But the query still returns [1 false].

(deffilterop [always-true [some-bool]]
  [x]
  (println "false?" (= some-bool false))
  (or some-bool true))

(?<- (stdout)
     [?value ?bool]
     ([[1]] ?value)
     (always-true [false] ?value :> ?bool))

RESULTS
-----------------------
1	false
-----------------------