;; Example query to wikidata listing cats                               
(use-modules
 (sparql driver)
 (ice-9 receive)
 (ice-9 rdelim)
 (web response))

(define q
  (sparql-query
   "
SELECT ?item
WHERE                                                                   
{                                                                       
?item wdt:P31 wd:Q146.                                                  
}                                                                       
LIMIT 10                                                                
"
   #:uri "https://query.wikidata.org/sparql"
   #:type "text/csv"
   #:store-backend 'blazegraph))
(display q)

(receive (header port)
    ;; Note: "text/csv" is the only format that is consistent for multiple SPARQL back-ends (Virtuoso, BlazeGraph, ...)
    q
  (if (= (response-code header) 200) ; This means the query went OK.
    (call-some-function port)
    #f)) ; Deal with errors at the #f.

(define (call-some-function port)
  (let ((line (read-line port)))
    (if (eof-object? line)
      #t
      (begin
        (format #t "Line: ~a~%" line)
        ;; Tail-recurse until we have processed each line.
        (call-some-function port)))))