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Is there a way to make GHC provide the type class constraints of typed holes?
...ng out-of-scope types
(use -fprint-potential-instances to see them all)
• In the expression: show _
In an equation for ‘it’: it = show _
<interactive>:3:6: error:
• Found hole: _ :: a0
Where: ‘a0’ is an ambiguous type variable
• In the first argum...
Why does Windows64 use a different calling convention from all other OSes on x86-64?
AMD has an ABI specification that describes the calling convention to use on x86-64. All OSes follow it, except for Windows which has it's own x86-64 calling convention. Why?
...
Inserting multiple rows in mysql
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When loading a table from a text file, use LOAD DATA INFILE. This is usually 20 times faster than using INSERT statements.
Optimizing INSERT Statements
You can find more tips on how to speed up your insert statements on the link above.
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How to obtain the number of CPUs/cores in Linux from the command line?
... Note that both of these will end up counting twice as many cores as actually exist if you're on a system with hyperthreading (e.g, P4, or Core i7).
– duskwuff -inactive-
Jun 26 '11 at 0:04
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How can I create directory tree in C++/Linux?
...C++ compilers.
/*
@(#)File: mkpath.c
@(#)Purpose: Create all directories in path
@(#)Author: J Leffler
@(#)Copyright: (C) JLSS 1990-2020
@(#)Derivation: mkpath.c 1.16 2020/06/19 15:08:10
*/
/*TABSTOP=4*/
#include "posixver.h"
#include "mkpath.h"
#include "emalloc...
In practice, what are the main uses for the new “yield from” syntax in Python 3.3?
...or v in g: yield v does not even begin to do justice to what yield from is all about. Because, let's face it, if all yield from does is expand the for loop, then it does not warrant adding yield from to the language and preclude a whole bunch of new features from being implemented in Python 2.x.
Wh...
Flatten nested dictionaries, compressing keys
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Basically the same way you would flatten a nested list, you just have to do the extra work for iterating the dict by key/value, creating new keys for your new dictionary and creating the dictionary at final step.
import collectio...
Update MongoDB field using value of another field
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The best way to do this is in version 4.2+ which allows using of aggregation pipeline in the update document and the updateOne, updateMany or update collection method. Note that the latter has been deprecated in most if not all languages drivers.
MongoDB 4.2+
Version 4.2 ...
Is it possible to create static classes in PHP (like in C#)?
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You can have static classes in PHP but they don't call the constructor automatically (if you try and call self::__construct() you'll get an error).
Therefore you'd have to create an initialize() function and call it in each method:
<?php
class Hello
{
private static...
How do you 'redo' changes after 'undo' with Emacs?
...ven a navigation command such as C-f) after a sequence of undo operations, all the undos are pushed on to the operation stack. So the next undo undoes the last command. Suppose you do have an operation sequence that looks like this:
Insert "foo"
Insert "bar"
Insert "I love spam"
Now, you undo....