allow `decode-linebreaks` to delete linebreaks

pollen/decode.rkt

@@ -121,10 +121,9 @@
        (memq (get-tag x) (setup:block-tags))
        #t))
 
-
 (define+provide/contract (decode-linebreaks elems [maybe-linebreak-proc '(br)]
                                             #:separator [newline (setup:linebreak-separator)])
-  ((txexpr-elements?) ((or/c txexpr-element? (txexpr-element? txexpr-element? . -> . txexpr-element?)) #:separator string?) . ->* . txexpr-elements?)
+  ((txexpr-elements?) ((or/c #f txexpr-element? (txexpr-element? txexpr-element? . -> . (or/c #f txexpr-element?))) #:separator string?) . ->* . txexpr-elements?)
   (define linebreak-proc (if (procedure? maybe-linebreak-proc)
                              maybe-linebreak-proc
                              (λ (e1 e2) maybe-linebreak-proc)))
@@ -145,6 +144,7 @@
 
 (module-test-external
  (check-equal? (decode-linebreaks '("foo" "\n" "bar")) '("foo" (br) "bar"))
+ (check-equal? (decode-linebreaks '("foo" "\n" "bar") #f) '("foo" "bar"))
  (check-equal? (decode-linebreaks '("\n" "foo" "\n" "bar" "\n")) '("\n" "foo" (br) "bar" "\n"))
  (check-equal? (decode-linebreaks '((p "foo") "\n" (p "bar"))) '((p "foo") (p "bar")))
  (check-equal? (decode-linebreaks '("foo" "\n" (p "bar"))) '("foo" (p "bar")))

pollen/private/ts.rktd

@@ -1 +1 @@
-1482013437
+1483835443

pollen/scribblings/decode.scrbl

@@ -282,16 +282,17 @@ Within @racket[_elements], merge sequential newline characters into a single ele
 @defproc[
 (decode-linebreaks
 [elements (listof xexpr?)]
-[linebreaker (or/c xexpr? (xexpr? xexpr? . -> . xexpr?)) '(br)])
+[linebreaker (or/c #f xexpr? (xexpr? xexpr? . -> . (or/c #f xexpr?))) '(br)])
 (listof xexpr?)]
 Within @racket[_elements], convert occurrences of the linebreak separator to @racket[_linebreaker], but only if the separator does not occur between blocks (see @racket[block-txexpr?]). Why? Because block-level elements automatically display on a new line, so adding @racket[_linebreaker] would be superfluous. In that case, the linebreak separator just disappears.
 
 The linebreak separator is controlled by @racket[setup:linebreak-separator], and defaults to @val[default-linebreak-separator].
 
-The @racket[_linebreaker] argument can either be an X-expression, or a function that takes two X-expressions and returns one. This function will receive the previous and next elements, to make contextual substitution possible.
+The @racket[_linebreaker] argument can either be @racket[#f] (which will delete the linebreaks), an X-expression (which will replace the linebreaks), or a function that takes two X-expressions and returns one. This function will receive the previous and next elements, to make contextual substitution possible.
 
 @examples[#:eval my-eval
 (decode-linebreaks '(div "Two items:" "\n" (em "Eggs") "\n" (em "Bacon")))
+(decode-linebreaks '(div "Two items:" "\n" (em "Eggs") "\n" (em "Bacon")) #f)
 (decode-linebreaks '(div "Two items:" "\n" (div "Eggs") "\n" (div "Bacon")))
 (decode-linebreaks '(div "Two items:" "\n" (em "Eggs") "\n" (em "Bacon"))
  (λ(prev next) (if (and (txexpr? prev) (member "Eggs" prev)) '(egg-br) '(br))))