[英]Clojure read the content of a lazy-seq ({ })
I'm new in Clojure. 我是Clojure的新手。 I have this problems:
我有这个问题:
I receive this data from a function: 我从一个函数收到此数据:
({:lat 40.4167754, :lng -3.7037902, :address Madrid, Spain})
When I ask for the class, I get: 当我上课时,我得到:
> class x
> clojure.lang.LazySeq
I need access to :lat, :lng, :address , but I don't know how. 我需要访问:lat,:lng,:address ,但是我不知道如何。
Try this: 尝试这个:
(defn mystery-fn []
(list {:lat 40.4167754, :lng -3.7037902, :address "Madrid, Spain"} )
)
(println :println (mystery-fn))
(prn :prn (mystery-fn))
(def a (first (mystery-fn)))
(prn :a a)
(def b (:lat a))
(prn :b b)
with output: 输出:
:reloading (tst.clj.core)
:println ({:lat 40.4167754, :lng -3.7037902, :address Madrid, Spain})
:prn ({:lat 40.4167754, :lng -3.7037902, :address "Madrid, Spain"})
:a {:lat 40.4167754, :lng -3.7037902, :address "Madrid, Spain"}
:b 40.4167754
Notice the difference between println
and prn
. 注意
println
和prn
之间的区别。 Using prn
, you get strings displayed with double-quotes which can help a lot when there are embedded spaces. 使用
prn
,您会得到显示带有双引号的字符串,这在嵌入空格时会很有帮助。
Also, when you want to label a printed output, it is often easier to use a keyword as the label like (prn :xyz ...)
instead of (println "xyz = " ...)
. 另外,当您要标记打印输出时,通常更容易使用关键字
(prn :xyz ...)
代替(println "xyz = " ...)
。
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