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What are free monads?
...ll x) = Roll (fmap (fmap f) x)
--this is the same thing as (++) basically
concatFree :: Functor f => Free f (Free f a) -> Free f a
concatFree (Pure x) = x
concatFree (Roll y) = Roll (fmap concatFree y)
instance Functor f => Monad (Free f) where
return = Pure -- just like []
x >>...
Why do pthreads’ condition variable functions require a mutex?
...pthread_cond_wait(&cond); //imagine cond_wait did not have a mutex
char *data = some_data;
some_data = NULL;
handle(data);
}
you'd naturally get a lot of race condition, what if the other thread did some_data = new_data right after you got woken up, but before you did data = some_d...
How to drop SQL default constraint without knowing its name?
... drop the constraint and dynamically execute it.
declare @schema_name nvarchar(256)
declare @table_name nvarchar(256)
declare @col_name nvarchar(256)
declare @Command nvarchar(1000)
set @schema_name = N'MySchema'
set @table_name = N'Department'
set @col_name = N'ModifiedDate'
select @Command = '...
Difference between 'new operator' and 'operator new'?
...ething like your own container, you can call operator new directly, like:
char *x = static_cast<char *>(operator new(100));
It's also possible to overload operator new either globally, or for a specific class. IIRC, the signature is:
void *operator new(size_t);
Of course, if you overloa...
Getting a list of files in a directory with a glob
...ing like that.
NSMutableArray* files = [NSMutableArray array];
glob_t gt;
char* pattern = "/bin/*";
if (glob(pattern, 0, NULL, &gt) == 0) {
int i;
for (i=0; i<gt.gl_matchc; i++) {
[files addObject: [NSString stringWithCString: gt.gl_pathv[i]]];
}
}
globfree(&gt);
retu...
Why does String.split need pipe delimiter to be escaped?
...ring "\\|" means the regular expression '\|' which means match exactly the character '|'.
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What does the ??!??! operator do in C?
...otnote 12 (h/t @Random832):
The trigraph sequences enable the input of characters that are not defined in the Invariant Code Set as
described in ISO/IEC 646, which is a subset of the seven-bit US ASCII code set.
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PHP validation/regex for URL
...
Some things that jump out at me: use of alternation where character classes are called for (every alternative matches exactly one character); and the replacement shouldn't have needed the outer double-quotes (they were only needed because of the pointless /e modifier on the regex).
...
Why can't Python's raw string literals end with a single backslash?
...string; for example, r"\"" is a
valid string literal consisting of two
characters: a backslash and a double
quote; r"\" is not a valid string
literal (even a raw string cannot end
in an odd number of backslashes).
Specifically, a raw string cannot end
in a single backslash (since the
...
How to read a single character from the user?
Is there a way of reading one single character from the user input? For instance, they press one key at the terminal and it is returned (sort of like getch() ). I know there's a function in Windows for it, but I'd like something that is cross-platform.
...