为什么这个匿名函数以println开头会导致NullPointerException？ [英] Why does this anonymous function starting with println result in a NullPointerException?

问题描述

我正在了解 pmap 并撰写了以下函数：

 （pmap＃（（printlnhello from（ - >（Thread / currentThread）.getName））
（+％1％2））
 [-1 1 1] [-1 -1 -1]）$ ​​b $ b  

运行时，结果是 NullPointerException

 （来自clojure-agent-send-off-pool-4 
 hello from clojure- agent-send-off-pool-3 
 hello从clojure-agent-send-off-pool-5 
 NullPointerException用户/ eval55 / fn  -  56（NO_SOURCE_FILE：11）
  

为什么会发生这种情况？我理解并观察了 fn 为 do

解决方案

匿名 fn literal ＃（）没有隐式 do p>


I am learning about pmap and wrote the following function:

(pmap #((println "hello from " (-> (Thread/currentThread) .getName)) 
         (+ %1 %2)) 
   [1 1 1] [-1 -1 -1])

When run, the result is a NullPointerException

(hello from  clojure-agent-send-off-pool-4
hello from  clojure-agent-send-off-pool-3
hello from  clojure-agent-send-off-pool-5
NullPointerException   user/eval55/fn--56 (NO_SOURCE_FILE:11)

Why is this happening? I have understood and observed the body of a fn to be an implicit do.

解决方案

The anonymous fn literal #() does not have an implicit do.

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