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Bash set +x without it being printed
...ution to this just recently when I became annoyed with it:
shopt -s expand_aliases
_xtrace() {
case $1 in
on) set -x ;;
off) set +x ;;
esac
}
alias xtrace='{ _xtrace $(cat); } 2>/dev/null <<<'
This allows you to enable and disable xtrace as in the following, wh...
Argparse optional positional arguments?
...se nargs='?' (or nargs='*' if you will need more than one dir)
parser.add_argument('dir', nargs='?', default=os.getcwd())
extended example:
>>> import os, argparse
>>> parser = argparse.ArgumentParser()
>>> parser.add_argument('-v', action='store_true')
_StoreTrueActi...
Split list into multiple lists with fixed number of elements
...st[List[X]] =
if (xs.size <= n) xs :: Nil
else (xs.splitAt(n)._1) :: split(n,xs.splitAt(n)._2)
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What is Weak Head Normal Form?
...es for an expression to be in WHNF:
A constructor: constructor expression_1 expression_2 ...
A built-in function with too few arguments, like (+) 2 or sqrt
A lambda-expression: \x -> expression
In other words, the head of the expression (i.e. the outermost function application) cannot be eval...
Naming of ID columns in database tables
...
ID is a SQL Antipattern.
See http://www.amazon.com/s/ref=nb_sb_ss_i_1_5?url=search-alias%3Dstripbooks&field-keywords=sql+antipatterns&sprefix=sql+a
If you have many tables with ID as the id you are making reporting that much more difficult. It obscures meaning and makes comp...
Time complexity of Sieve of Eratosthenes algorithm
...cause we need an array of n elements in any case?
– a_123
Mar 25 '16 at 21:35
...
Reading a binary file with python
...ve something to unpack is pretty trivial:
import struct
data = open("from_fortran.bin", "rb").read()
(eight, N) = struct.unpack("@II", data)
This unpacks the first two fields, assuming they start at the very beginning of the file (no padding or extraneous data), and also assuming native byte-or...
Using ping in c#
... InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
Ping p = new Ping();
PingReply r;
string s;
s = textBox1.Text;
r = p.Send(s);
i...
How can I convert immutable.Map to mutable.Map in Scala?
...table.Map(1->"one",2->"Two")
val n = collection.mutable.Map(m.toSeq: _*)
This works because a Map can also be viewed as a sequence of Pairs.
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Phonegap Cordova installation Windows
...Data\Roaming\npm\cordova -> C:\Users\binaryuser\AppData\Roaming\npm\node_modules\cordova\bin\cordova
cordova@3.0.9 C:\Users\binaryuser\AppData\Roaming\npm\node_modules\cordova
├── ncallbacks@1.0.0
├── open@0.0.3
├── colors@0.6.2
├── semver@1.1.0
├── shelljs@0.1.2
├...