On May 25, 2010, at 8:48 PM, Matthew Flatt wrote:
> #lang racket
> ;; Report each unique line from stdin:
> (let ([saw (make-hash)])
> (for ([line (in-lines)])
> (unless (hash-ref saw line #f)
> (displayln line))
> (hash-set! saw line #t)))
I would prefer to sacrifice one line to avoid the repetition of the test
(leakage). I doubt Perl and friends do that:
#lang racket
;; Report each unique line from stdin:
(define saw (make-hash))
(for ([line (in-lines)])
(hash-ref saw line
(lambda ()
(displayln line)
(hash-set! saw line #t))))
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