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Avoid eager evaluation of maybe-splice contents.

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This commit is contained in:
Tony Garnock-Jones 2016-08-02 19:13:51 -04:00
parent 77342cf9a0
commit aa22a98a4d
1 changed files with 2 additions and 2 deletions
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4
src/html-utils.rkt
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@ -9,8 +9,8 @@
;; Boolean XExpr ... -> (Listof XExpr) ;; Boolean XExpr ... -> (Listof XExpr)
;; Useful for optionally splicing in some contents to a list. ;; Useful for optionally splicing in some contents to a list.
;; If the guard is true, returns the contents; otherwise returns the empty list. ;; If the guard is true, returns the contents; otherwise returns the empty list.
(define (maybe-splice guard . contents) (define-syntax-rule (maybe-splice guard contents ...)
(if guard contents '())) (if guard (list contents ...) '()))
;; Extracts named single-valued bindings from the given request. ;; Extracts named single-valued bindings from the given request.
;; If a given binding is missing, the extracted value will be #f. ;; If a given binding is missing, the extracted value will be #f.