__Large case expressions__ will cause the optimizer to take a long time, as of 0.16. Here&#39;s the [discussion on Elm-Discuss](https://groups.google.com/forum/#!topic/elm-discuss/2ySK77lKYss) bringing up the issue, and a [gist of the nasty case match](https://gist.github.com/athanclark/0e29485cb245ff07a97730cfef365d10).

I have used interpolated strings for messages containing `string` variables like `$&quot;{EmployeeName}, {Department}&quot;`. Now I want to use an interpolated string for showing a formatted `double`.

Example

    var aNumberAsString = aDoubleValue.ToString(&quot;0.####&quot;);

How can I write it as an interpolated string? Something like `$&quot;{aDoubleValue} ....&quot;`

C# 6 how to format double using interpolated string?

I use Spring Boot with Spring Security and Cors Support. 

If I execute following code 

	url = &#39;http://localhost:5000/api/token&#39;
	xmlhttp = new XMLHttpRequest
	xmlhttp.onreadystatechange = -&gt;
		if xmlhttp.readyState is 4
			console.log	xmlhttp.status
	xmlhttp.open &quot;GET&quot;, url, true
	# xmlhttp.setRequestHeader &quot;X-Requested-With&quot;, &quot;XMLHttpRequest&quot;
	xmlhttp.setRequestHeader &#39;Authorization&#39;, &#39;Basic &#39; + btoa &#39;a:a&#39;
	do xmlhttp.send

I get as a result

    200

If I test with wrong credentials like

	url = &#39;http://localhost:5000/api/token&#39;
	xmlhttp = new XMLHttpRequest
	xmlhttp.onreadystatechange = -&gt;
		if xmlhttp.readyState is 4
			console.log	xmlhttp.status
	xmlhttp.open &quot;GET&quot;, url, true
	# xmlhttp.setRequestHeader &quot;X-Requested-With&quot;, &quot;XMLHttpRequest&quot;
	xmlhttp.setRequestHeader &#39;Authorization&#39;, &#39;Basic &#39; + btoa &#39;a:aa&#39;
	do xmlhttp.send

instead of getting 401 (that is the standard code for wrong authentication in spring security) I get

    0

with following browser notification:

GET http://localhost:5000/api/token

XMLHttpRequest cannot load http://localhost:5000. No &#39;Access-Control-Allow-Origin&#39; header is present on the requested resource. Origin &#39;http://localhost:3000&#39; is therefore not allowed access. The response had HTTP status code 401.

I&#39;m developing front-end code that needs useful http status codes from server responses to handle the situation. I need something more useful than 0. Also the response body is empty. I dont know if my config is wrong, or it&#39;s a software bug and I also don&#39;t know where, if it&#39;s chromium (using arch linux) or spring security.

My Spring Config is:

    @SpringBootApplication
    public class Application {
        public static void main(String[] args) {
            SpringApplication.run(Application.class, args);
        }
    }

    @RestController
    @RequestMapping(&quot;api&quot;)
    public class Controller {
        @RequestMapping(&quot;token&quot;)
        @CrossOrigin
        Map&lt;String, String&gt; token(HttpSession session) {
            return Collections.singletonMap(&quot;token&quot;, session.getId());
        }
    }

    @EnableWebSecurity
    public class WebSecurityConfiguration extends WebSecurityConfigurerAdapter {
        @Override
        protected void configure(AuthenticationManagerBuilder auth) throws Exception {
            auth.inMemoryAuthentication().withUser(&quot;a&quot;).password(&quot;a&quot;).roles(&quot;USER&quot;);
        }
        @Override
        protected void configure(HttpSecurity http) throws Exception {
            http
                    .authorizeRequests()
                    .requestMatchers(CorsUtils::isPreFlightRequest).permitAll()
                    .anyRequest().authenticated()
                    .and().httpBasic();
        }
    }

If I test with curl everything works perfect, I think because no CORS support needed, but I tried to simulate the CORS with OPTION requests and the result was also ok.

    $ curl -v localhost:5000/api/token -H &quot;Authorization: Basic YTpha&quot;
    *   Trying ::1...
    * Connected to localhost (::1) port 5000 (#0)
    &gt; GET /api/token HTTP/1.1
    &gt; Host: localhost:5000
    &gt; User-Agent: curl/7.48.0
    &gt; Accept: */*
    &gt; Authorization: Basic YTpha
    &gt; 
    &lt; HTTP/1.1 200 OK
    &lt; Server: Apache-Coyote/1.1
    &lt; X-Content-Type-Options: nosniff
    &lt; X-XSS-Protection: 1; mode=block
    &lt; Cache-Control: no-cache, no-store, max-age=0, must-revalidate
    &lt; Pragma: no-cache
    &lt; Expires: 0
    &lt; X-Frame-Options: DENY
    &lt; Access-Control-Allow-Origin: http://localhost:3000
    &lt; Access-Control-Allow-Methods: POST,GET,OPTIONS,DELETE
    &lt; Access-Control-Max-Age: 3600
    &lt; Access-Control-Allow-Credentials: true
    &lt; Access-Control-Allow-Headers: Origin,Accept,X-Requested-    With,Content-Type,Access-Control-Request-Method,Access-Control-Request-Headers,Authorization
    &lt; x-auth-token: 58e4cca9-7719-46c8-9180-2fc16aec8dff
    &lt; Content-Type: application/json;charset=UTF-8
    &lt; Transfer-Encoding: chunked
    &lt; Date: Sun, 01 May 2016 16:15:44 GMT
    &lt; 
    * Connection #0 to host localhost left intact
    {&quot;token&quot;:&quot;58e4cca9-7719-46c8-9180-2fc16aec8dff&quot;}

and with wrong credentials:

    $ curl -v localhost:5000/api/token -H &quot;Authorization: Basic YTp&quot;
    *   Trying ::1...
    * Connected to localhost (::1) port 5000 (#0)
    &gt; GET /api/token HTTP/1.1
    &gt; Host: localhost:5000
    &gt; User-Agent: curl/7.48.0
    &gt; Accept: */*
    &gt; Authorization: Basic YTp
    &gt; 
    &lt; HTTP/1.1 401 Unauthorized
    &lt; Server: Apache-Coyote/1.1
    &lt; X-Content-Type-Options: nosniff
    &lt; X-XSS-Protection: 1; mode=block
    &lt; Cache-Control: no-cache, no-store, max-age=0, must-revalidate
    &lt; Pragma: no-cache
    &lt; Expires: 0
    &lt; X-Frame-Options: DENY
    &lt; WWW-Authenticate: Basic realm=&quot;Realm&quot;
    &lt; Content-Type: application/json;charset=UTF-8
    &lt; Transfer-Encoding: chunked
    &lt; Date: Sun, 01 May 2016 16:16:15 GMT
    &lt; 
    * Connection #0 to host localhost left intact
    {&quot;timestamp&quot;:1462119375041,&quot;status&quot;:401,&quot;error&quot;:&quot;Unauthorized&quot;,&quot;message&quot;:&quot;Failed to decode basic authentication token&quot;,&quot;path&quot;:&quot;/api/token&quot;}


Edit:
To avoid misunderstandings. I use 1.3.3 Spring Boot.
The Blog post writes:

&gt; CORS support will be available in the upcoming Spring Boot 1.3 release, and is already available in the 1.3.0.BUILD-SNAPSHOT builds.
&gt; 
&gt; Using controller method CORS configuration with @CrossOrigin annotations in your Spring Boot application does not require any specific configuration.
&gt; 
&gt; Global CORS configuration can be defined by registering a WebMvcConfigurer bean with a customized addCorsMappings(CorsRegistry) method:

I have added following code to enable global cors support. actually I have tried this before but it the result was the same. I tried it again recently and the result is the same.

    @Configuration
    public class MyConfiguration {

        @Bean
        public WebMvcConfigurer corsConfigurer() {
            return new WebMvcConfigurerAdapter() {
                @Override
                public void addCorsMappings(CorsRegistry registry) {
                    registry.addMapping(&quot;/**&quot;);
                }
            };
        }
    }


The idea, that the problem comes from a redirect between the authorization process is an interesting though. how can i change the redirect to any resources to avoid this conflict?

EDIT:

I guess I am closer to a solution. I have tested with my nodejs server that supports cors without problems by adding 
Access-Control-Allow-Origin: *
to all requests.

Like Stefan Isele has already mentioned it seems that spring security redirects or doesn&#39;t add the CORS header so that&#39;s why the request seems to be broken. So while spring security is checking the authentification it has to add the proper header.

Does anyone know how to do so?

EDIT:

I found a workaround, that seems to be ugly. I have started a github issue for spring boot where I describe the workaround: https://github.com/spring-projects/spring-boot/issues/5834

How to configure CORS in a Spring Boot + Spring Security application?

I&#39;m not sure what&#39;s causing this issue, but in a project, I&#39;m building, the compiler is taking hours just to compile a module. The total size of my codebase is 352KB, but none of the modules are over 10KB large. I am using a Native port, but it&#39;s very trivial; I&#39;m just fetching `Date.now()` with it.

Is there anything well-known that would cause the elm compiler to take forever to compile? I don&#39;t have many dependencies, but I&#39;m using Html a lot. I would really appreciate any hints as to what would cause this.

# Edit

So it turns out __large case expressions__ will cause the optimizer to take a long time, as of 0.16. Here&#39;s the [discussion on Elm-Discuss](https://groups.google.com/forum/#!topic/elm-discuss/2ySK77lKYss) bringing up the issue, and a [gist of the nasty case match](https://gist.github.com/athanclark/0e29485cb245ff07a97730cfef365d10).

I guess to be verbose and to keep a carrot out there, why would elm&#39;s compiler take this route for case-matching? What&#39;s the underlying machinery going on here? Why would the compiler take longer than an hour for optimizing 60+ pattern matches on a case statement?

Elm Compiler running forever, computer just getting hot

I'm not sure what's causing this issue, but in a project, I'm building, the compiler is taking hours just to compile a module. The total size of my codebase is 352KB, but none of the modules are over 10KB large. I am using a Native port, but it's very trivial; I'm just fetching <code>Date.now()</code> with it.
Is there anything well-known that would cause the elm compiler to take forever to compile? I don't have many dependencies, but I'm using Html a lot. I would really appreciate any hints as to what would cause this.
<h3 id="edit"><a aria-hidden="true" tabindex="-1" href="#edit"></a>Edit</h3>
So it turns out large case expressions will cause the optimizer to take a long time, as of 0.16. Here's the <a href="https://groups.google.com/forum/#!topic/elm-discuss/2ySK77lKYss" target="_blank" rel="noopener noreferrer">discussion on Elm-Discuss</a> bringing up the issue, and a <a href="https://gist.github.com/athanclark/0e29485cb245ff07a97730cfef365d10" target="_blank" rel="noopener noreferrer">gist of the nasty case match</a>.
I guess to be verbose and to keep a carrot out there, why would elm's compiler take this route for case-matching? What's the underlying machinery going on here? Why would the compiler take longer than an hour for optimizing 60+ pattern matches on a case statement?

Is there any difference between `switch` and `select` in Go,   
apart from the fact that one takes an argument and the other not?

What is the difference between switch and select in Go?

What happens when you reach the end of a Go case, does it fall through to the next, or assume that most applications don&#39;t want to fall through?

Do Go switch/cases fallthrough or not?

Through a little typo, I accidentally found this construct:

    int main(void) {
    	char foo = &#39;c&#39;;
     
    	switch(foo)
    	{
    		printf(&quot;Cant Touch This\n&quot;);   // This line is Unreachable

    		case &#39;a&#39;: printf(&quot;A\n&quot;); break;
    		case &#39;b&#39;: printf(&quot;B\n&quot;); break;
    		case &#39;c&#39;: printf(&quot;C\n&quot;); break;
    		case &#39;d&#39;: printf(&quot;D\n&quot;); break;
    	}
     
    	return 0;
    }

It seems that the `printf` at the top of the `switch` statement is valid, but also completely unreachable.

I got a clean compile, without even a warning about unreachable code, but this seems pointless.

Should a compiler flag this as unreachable code?&lt;br&gt;
Does this serve any purpose at all?

Valid, but worthless syntax in switch-case?

What&#39;s the difference between:

    switch (expression) {
        case:
          somethings;
          break;
    }

and

    switch (expression) {
        case: {
          somethings;
          break;
        }
    }

At first I thought that I could return an object literal like so, but it turns out it&#39;s a syntax error. What&#39;s the difference actually?

Example from another question:
https://stackoverflow.com/questions/42475118/how-to-pass-switch-statement-as-function-argument-in-javascript-es6/42475344#42475344

What do the curly braces do in switch statement after case in es6?

Given the following code:

    string someString = null;
    switch (someString)
    {
        case string s:
            Console.WriteLine(&quot;string s&quot;);
            break;
        case var o:
            Console.WriteLine(&quot;var o&quot;);
            break;
        default:
            Console.WriteLine(&quot;default&quot;);
            break;
    }

Why is the switch statement matching on `case var o`?

It is my understanding that `case string s` does not match when `s == null` because (effectively) `(null as string) != null` evaluates to false. IntelliSense on VS Code tells me that `o` is a `string` as well. Any thoughts?

---

Similiar to: https://stackoverflow.com/questions/42950833/c-sharp-7-switch-case-with-null-checks

switch with var/null strange behavior

I have a file like the following and I would like to print the lines between two given patterns `PAT1` and `PAT2`.

```lang-none
1
2
PAT1
3    - first block
4
PAT2
5
6
PAT1
7    - second block
PAT2
8
9
PAT1
10    - third block
```

I have read [How to select lines between two marker patterns which may occur multiple times with awk/sed][1] but I am curious to see all the possible combinations of this, either including or excluding the pattern.

How can I print all lines between two patterns?


  [1]: https://stackoverflow.com/q/17988756/1983854

How to print lines between two patterns, inclusive or exclusive (in sed, AWK or Perl)?

In C# 7, we can use

    if (x is null) return;

instead of

    if (x == null) return;

Are there any advantages to using the new way (former example) over the old way?

Are the semantics any different?

Is it just a matter of taste? If not, when should I use one over the other?

Reference: [What’s New in C# 7.0][1].


[1]: https://devblogs.microsoft.com/dotnet/whats-new-in-csharp-7-0/

What is the difference between &quot;x is null&quot; and &quot;x == null&quot;?

Coming from react, I am learning to understand Elm.

In the [Todomvc example code][1], there is the following code snippet:

    -- How we update our Model on a given Msg?
    update : Msg -&gt; Model -&gt; ( Model, Cmd Msg )
    update msg model =
      case msg of
        NoOp -&gt;
          model ! []        &lt;-- What is this?

What I (think I) understand, is that the `update` function takes in a `msg` of type `Msg` and a `model` of type `Model`, and returns a tuple of containing a `Model` and a `Cmd Msg`.

But how should I read the return statement?

    model ! []

What does this statement mean? return a &quot;model [something] empty list&quot;?  
Did I miss something in the docs where this is explained? (Googling &quot;elm !&quot; did not get me far :)

  [1]: https://github.com/evancz/elm-todomvc/blob/master/Todo.elm


Content Type	Original Author	Original Content on Stackoverflow
Question	Athan Clark	View Question on Stackoverflow
Solution 1 - Switch Statement	Philip Whitehouse	View Answer on Stackoverflow

Elm Compiler running forever, computer just getting hot

Switch Statement Problem Overview

Edit

Switch Statement Solutions

Solution 1 - Switch Statement

How to configure CORS in a Spring Boot + Spring Security application?

C# 6 how to format double using interpolated string?

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