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How can I get nth element from a list?
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Personally I can't comprehend how an at-index accessor that doesn't return a Maybe type is acceptable as idiomatic Haskell. [1,2,3]!!6 will give you a runtime error. It could very easily be avoided if !! had the type [a] -> Int ...
Super-simple example of C# observer/observable with delegates
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The observer pattern is usually implemented with events.
Here's an example:
using System;
class Observable
{
public event EventHandler SomethingHappened;
public void DoSomething() =>
SomethingHappened?.Invoke(this, EventArgs.Empt...
Types in MySQL: BigInt(20) vs Int(20)
...gInt , MediumInt , and Int are... it would seem obvious that they would allow for larger numbers; however, I can make an Int(20) or a BigInt(20) and that would make seem that it is not necessarily about size.
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How do I check if a string is valid JSON in Python?
...SON.
In general, the "Pythonic" philosophy for this kind of situation is called EAFP, for Easier to Ask for Forgiveness than Permission.
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Proper use of beginBackgroundTaskWithExpirationHandler
...l need to wrap it in a background task. It's also very important that you call endBackgroundTask when you're finished - otherwise the app will be killed after its allotted time has expired.
Mine tend look something like this:
- (void) doUpdate
{
dispatch_async(dispatch_get_global_queue(DISPAT...
How to specify different Debug/Release output directories in QMake .pro file
...ke things even easier to switch around, only define your DESTDIRs conditionally, and then use that value in all your other paths: OBJECTS_DIR = $${DESTDIR}/.obj. Cheers!
– Xavier Holt
Mar 7 '12 at 4:16
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Simple example of threading in C++
...ill execute, followed by the function's parameters. The thread is automatically started upon construction.
If later on you want to wait for the thread to be done executing the function, call:
t1.join();
(Joining means that the thread who invoked the new thread will wait for the new thread to fi...
What characters are valid for JavaScript variable names?
...ou an idea of how wrong Anthony Mills' answer is: if you were to summarize all these rules in a single ASCII-only regular expression for JavaScript, it would be 11,236 characters long. Here it is:
// ES5.1 / Unicode 6.1
/^(?!(?:do|if|in|for|let|new|try|var|case|else|enum|eval|false|null|this|true|v...
What's the need of array with zero elements?
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This is a way to have variable sizes of data, without having to call malloc (kmalloc in this case) twice. You would use it like this:
struct bts_action *var = kmalloc(sizeof(*var) + extra, GFP_KERNEL);
This used to be not standard and was considered a hack (as Aniket said), but it was s...
In Django, how do I check if a user is in a certain group?
...add(group) # user is now in the "Editor" group
then user.groups.all() returns [<Group: Editor>].
Alternatively, and more directly, you can check if a a user is in a group by:
if django_user.groups.filter(name = groupname).exists():
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Note that groupname can also be the ac...