Question

我是clojure的新手，目前仍然坚持使用map函数。我尝试了以下代码：

(map #(str "Hello " % "!" ) ["Ford" "Arthur" "Tricia"])

它回来了：

#object[clojure.core.async.impl.channels.ManyToManyChannel 0x2eaf8b7c "clojure.core.async.impl.channels.ManyToManyChannel@2eaf8b7c"]

虽然我想：

("Hello Ford!" "Hello Arthur!" "Hello Tricia!"])

我跟着 the clojure.core/map documentation example但它没有按预期工作..

Answer 1

看起来您可能已将clojure.core/map替换为clojure.core.async/map。这种情况最常见的方式是在你的repl上做一些这样的事情（请注意当你这样做的时候会有很多警告告诉你）：

user=> (use 'clojure.core.async)
WARNING: reduce already refers to: #'clojure.core/reduce in namespace: user, being replaced by: #'clojure.core.async/reduce
WARNING: take already refers to: #'clojure.core/take in namespace: user, being replaced by: #'clojure.core.async/take
WARNING: map already refers to: #'clojure.core/map in namespace: user, being replaced by: #'clojure.core.async/map
WARNING: transduce already refers to: #'clojure.core/transduce in namespace: user, being replaced by: #'clojure.core.async/transduce
WARNING: into already refers to: #'clojure.core/into in namespace: user, being replaced by: #'clojure.core.async/into
WARNING: partition already refers to: #'clojure.core/partition in namespace: user, being replaced by: #'clojure.core.async/partition
WARNING: merge already refers to: #'clojure.core/merge in namespace: user, being replaced by: #'clojure.core.async/merge
WARNING: partition-by already refers to: #'clojure.core/partition-by in namespace: user, being replaced by: #'clojure.core.async/partition-by

您可以随时使用它的限定名称明确引用某个功能：

(clojure.core/map #(str "Hello " % "!" ) ["Ford" "Arthur" "Tricia"])

通常情况下，尽管最好避免使用use而不是require另一个命名空间，而是给它一个别名：

(require '[clojure.core.async :as async])

这样，您的clojure.core/map仍然可以用作map（因为所有clojure.core函数都是自动引用的），而异步版本可以称为async/map。< / p>

为什么clojure中的map返回异步chan而不是字符串序列？

1 个答案: