splainer

splainer.rkt

#lang racket

(define verbose-mode (make-parameter #f))


(define input-file
  (command-line

   #:program "splain"

   #:once-each
   [("-v" "--verbose") "Search with verbose messages"
                        (verbose-mode #t)]

   #:args (effect:causes-file) ; expect one command-line argument: <effect:causes>

   effect:causes-file))


(define effect:causes (read (open-input-file input-file)))



(define (splain effect:causes-list)
  
  (define cause=>effects (make-hash))

  (define (add-cause! cause effect)
    (define current-effects (hash-ref cause=>effects cause (set)))
    (hash-set! cause=>effects cause (set-add current-effects effect)))

  (for ([e:cs effect:causes-list])
    (define e (car e:cs))
    (define cs (cadr e:cs))
    (for ([c cs])
       (add-cause! c e)))

  (define (c:es< e1 e2)
    (< (set-count (cdr e1)) (set-count (cdr e2))))

  (define cause=>effects* (hash->list cause=>effects))
  
  (define sorted-cause=>effects (sort cause=>effects* c:es<))

  (map (lambda (e) 
        (match e 
         [`(,cause . ,effects) `(,cause ,(set->list effects))]))
       sorted-cause=>effects))

  


(pretty-write (splain effect:causes))