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Can someone explain the traverse function in Haskell?
...user IDs to usernames looks like:
mapUserIDsToUsernames :: (Num -> IO String) -> [Num] -> IO [String]
mapUserIDsToUsernames fn ids = traverse fn ids
There's also a function called mapM:
mapM :: (Traversable t, Monad m) => (a -> m b) -> t a -> m (t b)
Any use of mapM can...
How to determine the number of days in a month in SQL Server?
... or just use it inline. This answers the original question without all the extra junk in the other answers.
examples for dates from other answers:
SELECT DAY(DATEADD(DD,-1,DATEADD(MM,DATEDIFF(MM,-1,'1/31/2009'),0))) Returns 31
SELECT DAY(DATEADD(DD,-1,DATEADD(MM,DATEDIFF(MM,-1,'2404-feb-15'),0)))...
How to make IntelliJ IDEA insert a new line at every end of file?
...s it possible to force only one? I.e. if there is 2 or more it deletes the extra newlines?
– Pylinux
Oct 25 '14 at 11:28
...
phpinfo() - is there an easy way for seeing it?
... My webhost (debian 7): php -r 'phpinfo();' Error in argument 1, char 2: option not found r php -v PHP 4.4.9 (cgi-fcgi) (built: Feb 28 2017 11:31:58)
– Prisoner 13
Sep 27 '17 at 8:22
...
Most efficient method to groupby on an array of objects
...ypeScript signature: var groupBy = function<TItem>(xs: TItem[], key: string) : {[key: string]: TItem[]} { ...
– Michael Sandino
Dec 7 '17 at 9:47
...
Pass Array Parameter in SqlCommand
...l need to add the values in the array one at a time.
var parameters = new string[items.Length];
var cmd = new SqlCommand();
for (int i = 0; i < items.Length; i++)
{
parameters[i] = string.Format("@Age{0}", i);
cmd.Parameters.AddWithValue(parameters[i], items[i]);
}
cmd.CommandText = str...
Is null reference possible?
...red_ptr<Error>> _instances;
static Error& NewInstance(const string& name, bool isNull = false);
private:
bool _isNull;
Error(const string& name, bool isNull = false) : _name(name), _isNull(isNull) {};
Error() {};
Error(const Error& src) {};
Error& operator=(...
How to force the browser to reload cached CSS/JS files?
...HP function:
/**
* Given a file, i.e. /css/base.css, replaces it with a string containing the
* file's mtime, i.e. /css/base.1221534296.css.
*
* @param $file The file to be loaded. Must be an absolute path (i.e.
* starting with slash).
*/
function auto_version($file)
{
...
Task not serializable: java.io.NotSerializableException when calling function outside closure only o
...the outer class, you can't do it. But FileWriter can be constructed from a String or a File, both of which are Serializable. So refactor your code to construct a local FileWriter based on the filename from the outer class.
– Trebor Rude
Jul 23 '15 at 16:10
...
What does Visual Studio mean by normalize inconsistent line endings?
...iewing a file originating from a Windows computer on a
Unix system, the extra CR may be displayed as ^M or at the end of each line or as a
second line break.
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