;; Extension — synonym / query expansion.
;; synmap: car -> automobile, vehicle ; big -> large
;; Corpus: 1 "fast car"  2 "shiny automobile"  3 "big truck"  4 "large house"  5 "vehicle review"

(define
  syn-setup
  "synmap = [(\"car\", [\"automobile\", \"vehicle\"]), (\"big\", [\"large\"])]\nidx = indexDoc 5 \"vehicle review\" (indexDoc 4 \"large house\" (indexDoc 3 \"big truck\" (indexDoc 2 \"shiny automobile\" (indexDoc 1 \"fast car\" emptyIndex))))\n")

(define
  syn-cases
  (list
    (list
      "expand term with synonyms"
      "expandTerm synmap \"car\""
      (list "car" "automobile" "vehicle"))
    (list
      "expand single synonym"
      "expandTerm synmap \"big\""
      (list "big" "large"))
    (list "expand unknown term" "expandTerm synmap \"banana\"" (list "banana"))
    (list
      "syn docs union"
      "synDocs synmap \"car\" idx"
      (list 1 2 5))
    (list
      "syn docs single synonym"
      "synDocs synmap \"big\" idx"
      (list 3 4))
    (list
      "syn docs no synonyms"
      "synDocs synmap \"house\" idx"
      (list 4))
    (list "syn docs absent" "synDocs synmap \"plane\" idx" (list))
    (list
      "syn rank expanded"
      "synRankTfIdf synmap \"car\" idx"
      (list 1 2 5))
    (list
      "syn rank single"
      "synRankTfIdf synmap \"big\" idx"
      (list 3 4))))

(define
  syn-results
  (search-batch syn-setup (map (fn (c) (nth c 1)) syn-cases)))

(map-indexed
  (fn
    (i c)
    (hk-test (nth c 0) (nth syn-results i) (nth c 2)))
  syn-cases)

{:fail hk-test-fail :pass hk-test-pass :fails hk-test-fails}