(rest a-seq) and (drop 1 a-seq) aren't equivalent anymore:user=> (def s (map #(do (println %) %) (range 10)))
#'user/s
user=> (def d (drop 1 s))
#'user/d
user=> (def r (rest s))
0
#'user/r
rest needs to realize the first element of s while drop doesn't. The corollary is that (drop n s) holds on the whole seq (including the nth first elements) while rest computes the first element and then discards it.
#'var-name to access a shadowed global.namespace-where-defined-or-alias/var-name.#'var-name:
(def a (map str (range 10)))
(def b (map #'str (range 10)))
(take 5 a)
("0" "1" "2" "3" "4")
(take 5 b)
("0" "1" "2" "3" "4")
(binding [str identity] (doall a))
("0" "1" "2" "3" "4" "5" "6" "7" "8" "9")
(binding [str identity] (doall b))
("0" "1" "2" "3" "4" 5 6 7 8 9)
@#'var-name is better than #'var-name but, really, just use the namespaced symbol.
(add-classpath "http://clojure-contrib.svn.sourceforge.net/viewvc/clojure-contrib/trunk/src/") ; sourceforge
(add-classpath "http://github.com/Lau-of-DK/clojureql/raw/master/src/"); github
(require '[clojure.contrib.duck-streams :as duck])
(require '[dk.bestinclass.clojureql :as ql])
add-classpath is not meant to be used anywhere but at the repl,what is the best way to bind vars to a value when sending to an agent?
(defmacro capture-and-send
"Capture the current value of the specified vars and rebind
them on the agent thread before executing the action."
[vars agent action & args]
(let [locals (map #(gensym (name %)) vars)]
`(let [~@(interleave locals vars)
action# (fn [& args#]
(binding [~@(interleave vars locals)]
(apply ~action args#)))]
(send ~agent action# ~@args))))
;; usage:
(capture-and-send [*out*] a f b c)
(deftemplate microblog-template "net/cgrand/enlive_html/example.html" [title posts](NB: manually edited to add linebreaks.)
[:title] title
[:h1] title
[:div.no-msg] (when-not (seq posts) ~(html/show))
[:div.post] (for [{:keys [title body]} posts]
~(at
[:h2] title
[:p] body)))
;; at the repl:
net.cgrand.enlive-html.examples=> (apply str (microblog-template "Hello user!"
[{:title "post #1"
:body "hello with dangerous chars: <>&"}
{:title "post #2"
:body "dolor ipsum"}]))
"<html><head><title>Hello user!</title></head>
<body><h1>Hello user!</h1>
<div class=\"post\"><h2>post #1</h2>
<p>hello with dangerous chars: <>&</p></div>
<div class=\"post\"><h2>post #2</h2>
<p>dolor ipsum</p></div></body></html>"
(defmacro try-or
"Evaluates exprs one at a time, from left to right. If a form returns a
value, this value is returned. If a form throws an exception, the next
form is evaluated.
If the last form throws an exception, the exception isn't caught."
([] nil)
([form] form)
([form & forms]
`(try
~form
(catch Exception e#
(try-or ~@forms)))))
