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What are type lambdas in Scala and what are their benefits?
...ction of Either[A, B]. The monad typeclass looks like this:
trait Monad[M[_]] {
def point[A](a: A): M[A]
def bind[A, B](m: M[A])(f: A => M[B]): M[B]
}
Now, Either is a type constructor of two arguments, but to implement Monad, you need to give it a type constructor of one argument. The sol...
What is the use of static constructors?
...required configuration data into readonly fields, etc.
It is run automatically by the runtime the first time it is needed (the exact rules there are complicated (see "beforefieldinit"), and changed subtly between CLR2 and CLR4). Unless you abuse reflection, it is guaranteed to run at most once (eve...
How can I use an array of function pointers?
...l; /* address of mul() */
p[3] = div; /* address of div() */
[...]
To call one of those function pointers:
result = (*p[op]) (i, j); // op being the index of one of the four functions
share
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...
What is the best way to repeatedly execute a function every x seconds?
...uler.
import sched, time
s = sched.scheduler(time.time, time.sleep)
def do_something(sc):
print("Doing stuff...")
# do your stuff
s.enter(60, 1, do_something, (sc,))
s.enter(60, 1, do_something, (s,))
s.run()
If you're already using an event loop library like asyncio, trio, tkinter,...
How do you run a Python script as a service in Windows?
...mport socket
class AppServerSvc (win32serviceutil.ServiceFramework):
_svc_name_ = "TestService"
_svc_display_name_ = "Test Service"
def __init__(self,args):
win32serviceutil.ServiceFramework.__init__(self,args)
self.hWaitStop = win32event.CreateEvent(None,0,0,None)
...
Why does printf not flush after the call unless a newline is in the format string?
Why does printf not flush after the call unless a newline is in the format string? Is this POSIX behavior? How might I have printf immediately flush every time?
...
BLE协议—广播和扫描 - 创客硬件开发 - 清泛IT社区，为创新赋能！
...广播方式的报文有4种，分别为可连接的非定向广播（ADV_IND）、可连接的定向广播（ADV_DIRECT_IND）、可扫描非定向广播（ADV_SCAN_IND）、不可连接的非定向广播（ADV_NONCONN_IND）
4种广播的使用场景各不相同
可连接的非定向广播（ADV...
What is the strict aliasing rule?
...n(void)
{
// Get a 32-bit buffer from the system
uint32_t* buff = malloc(sizeof(Msg));
// Alias that buffer through message
Msg* msg = (Msg*)(buff);
// Send a bunch of messages
for (int i = 0; i < 10; ++i)
{
msg->a = i;
msg->b = i+1;...
LINQ - Full Outer Join
...
I don't know if this covers all cases, logically it seems correct. The idea is to take a left outer join and right outer join then take the union of the results.
var firstNames = new[]
{
new { ID = 1, Name = "John" },
new { ID = 2, Name = "Sue"...
Zip lists in Python
...x. list, string, tuple, dictionary)
Output (list)
1st tuple = (element_1 of numbers, element_1 of letters)
2nd tuple = (e_2 numbers, e_2 letters)
…
n-th tuple = (e_n numbers, e_n letters)
List of n tuples: n is the length of the shortest argument (input)
len(numbers) =...