<h3 class="group flex justify-start items-center">问题描述<a name="问题描述" aria-label="Anchor" id="问题描述" class="inline-flex justify-center items-center w-6 h-6 ml-4 text-base rounded-sm bg-gray/100 decoration-transparent invisible group-hover:visible" href="#问题描述">#</a></h3><blockquote>
<p>Who first said the following?A monad is just a monoid in the
  category of endofunctors, what&#39;s the
  problem?And on a less important note, is this true and if so could you give an explanation (hopefully one that can be understood by someone who doesn&#39;t have much Haskell experience)?</p>
</blockquote>
<h3 class="group flex justify-start items-center">提示词<a name="提示词" aria-label="Anchor" id="提示词" class="inline-flex justify-center items-center w-6 h-6 ml-4 text-base rounded-sm bg-gray/100 decoration-transparent invisible group-hover:visible" href="#提示词">#</a></h3><pre><code class="language-bash"><span class="hljs-attribute">None</span>
</code></pre>


A monad is just a monoid in the category of endofunctors, whats the problem?

<h3 class="group flex justify-start items-center">问题描述<a name="问题描述" aria-label="Anchor" id="问题描述" class="inline-flex justify-center items-center w-6 h-6 ml-4 text-base rounded-sm bg-gray/100 decoration-transparent invisible group-hover:visible" href="#问题描述">#</a></h3><blockquote>
<p>I&#39;m using the subprocess module to start a subprocess and connect to its output stream (standard output). I want to be able to execute non-blocking reads on its standard output. Is there a way to make .readline non-blocking or to check if there is data on the stream before I invoke .readline? I&#39;d like this to be portable or at least work under Windows and Linux.Here is how I do it for now (it&#39;s blocking on the .readline if no data is available):</p>
</blockquote>
<h3 class="group flex justify-start items-center">提示词<a name="提示词" aria-label="Anchor" id="提示词" class="inline-flex justify-center items-center w-6 h-6 ml-4 text-base rounded-sm bg-gray/100 decoration-transparent invisible group-hover:visible" href="#提示词">#</a></h3><pre><code class="language-bash"><span class="hljs-attribute">None</span>
</code></pre>


A non-blocking read on a subprocess.PIPE in Python

<h3 class="group flex justify-start items-center">问题描述<a name="问题描述" aria-label="Anchor" id="问题描述" class="inline-flex justify-center items-center w-6 h-6 ml-4 text-base rounded-sm bg-gray/100 decoration-transparent invisible group-hover:visible" href="#问题描述">#</a></h3><blockquote>
<p>I like how Java has a Map where you can define the types of each entry in the map, for example &lt;String, Integer&gt;. What I&#39;m looking for is a type of collection where each element in the collection is a pair of values.  Each value in the pair can have its own type (like the String and Integer example above), which is defined at declaration time.  The collection will maintain its given order and will not treat one of the values as a unique key (as in a map).  Essentially I want to be able to define an ARRAY of type &lt;String,Integer&gt; or any other 2 types.  I realize that I can make a class with nothing but the 2 variables in it, but that seems overly verbose.  I also realize that I could use a 2D array, but because of the different types I need to use, I&#39;d have to make them arrays of OBJECT, and then I&#39;d have to cast all the time.  I only need to store pairs in the collection, so I only need two values per entry.  Does something like this exist without going the class route?  Thanks!</p>
</blockquote>
<h3 class="group flex justify-start items-center">提示词<a name="提示词" aria-label="Anchor" id="提示词" class="inline-flex justify-center items-center w-6 h-6 ml-4 text-base rounded-sm bg-gray/100 decoration-transparent invisible group-hover:visible" href="#提示词">#</a></h3><pre><code class="language-bash"><span class="hljs-attribute">None</span>
</code></pre>


A monad is just a monoid in the category of endofunctors, whats the problem?

问题描述#

提示词#

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