Hi everyone,
Is there a reason to use the function "datum-intern-literal" on a list
structure? According to the documentation, datum-intern-literal does
not traverse compound values, so I'm unsure about its use on list
structures.
I'm curious because I'm staring at the definition of decode-string in
scribble/decode, and it's trying to apply datum-intern-literal against
a whole list, which seems strange to me:
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(define (decode-string s)
(let loop ([l '((#rx"---" mdash)
(#rx"--" ndash)
(#rx"``" ldquo)
(#rx"''" rdquo)
(#rx"'" rsquo))])
(cond [(null? l) (list s)]
[(regexp-match-positions (caar l) s)
=> (lambda (m)
(datum-intern-literal
(append (decode-string (substring s 0 (caar m)))
(cdar l)
(decode-string (substring s (cdar m))))))]
[else (loop (cdr l))])))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
I'm looking at this function because the Racket statistical profiler
is telling me that it might be helpful to optimize it. I had expected
something more along the lines of:
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(define (decode-string s)
(define pattern #rx"(---|--|``|''|')")
(let loop ([start 0])
(cond
[(regexp-match-positions pattern s start)
=> (lambda (m)
(define the-match (substring s (caar m) (cdar m)))
(list* (substring s start (caar m))
(cond
[(string=? the-match "---") 'mdash]
[(string=? the-match "--") 'ndash]
[(string=? the-match "``") 'ldquo]
[(string=? the-match "''") 'rdquo]
[(string=? the-match "'") 'rsquo])
(loop (cdar m))))]
[else
(list (substring s start))])))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
but I'm not sure about the role of the datum-intern-literal stuff with
regards to lists.
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