什么是较短的写作方式？（\ x - > traceShow x x）`？ [英] What's a shorter way of writing `(\ x -> traceShow x x )`?

问题描述

打印表达式的值是调试中常见的做法。例如，如果我有这样一段代码，那么

Printing the value of an expression is a common practice in debugging. For example, if I have a piece of code like this

my . super . cool . fUnCtIoN . chain $ value

，我试图看到 fUnCtIoN的输出。链，我会添加

and I am trying to see the output of fUnCtIoN . chain, I would add

my . super . cool . (\ x -> traceShow x x ) . fUnCtIoN . chain $ value

这是一个简单的任务，这样，更不用说我是否要打印许多中间结果：

which is mouthful for a simple task like this, not to mention if I want to print many intermediate results:

(\ x -> traceShow x x )
    . my
    . (\ x -> traceShow x x )
    . super
    . (\ x -> traceShow x x )
    . cool
    . (\ x -> traceShow x x )
    . fUnCtIoN
    . (\ x -> traceShow x x )
    . chain
    $ value

它只会看起来很糟糕。有更好的方法吗？

It would just look awful. Is there a better way to do this?

推荐答案

只需使用 traceShowId ！它正是你要求的。

Just use traceShowId! It does exactly what you're asking for.

my . super . cool . traceShowId . fUnCtIoN . chain $ value

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