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What is a higher kinded type in Scala?
...n also be spelled (* ⇒ *) ⇒ * ⇒ *. It can be expressed in Scala like Foo[F[_], T]. This the kind of a type like (in Haskell) newtype Twice f a = Twice (f (f a)) (e.g., Twice Maybe Int ≅ Maybe (Maybe Int), Twice [] Char ≅ [[Char]]) or something more interesting like the free monad data Free...
What is the difference between __init__ and __call__?
...ialise newly created object, and receives arguments used to do that:
class Foo:
def __init__(self, a, b, c):
# ...
x = Foo(1, 2, 3) # __init__
The second implements function call operator.
class Foo:
def __call__(self, a, b, c):
# ...
x = Foo()
x(1, 2, 3) # __call__
...
CMake link to external library
...
I assume you want to link to a library called foo, its filename is usually something link foo.dll or libfoo.so.
1. Find the library
You have to find the library. This is a good idea, even if you know the path to your library. CMake will error out if the library vanished...
When do we need curly braces around shell variables?
...ence. However, the {} in ${} are useful if you want to expand the variable foo in the string
"${foo}bar"
since "$foobar" would instead expand the variable identified by foobar.
Curly braces are also unconditionally required when:
expanding array elements, as in ${array[42]}
using parameter exp...
git - Find commit where file was added
Say I have a file foo.js that was committed some time ago. I would like to
simply find the commit where this file was first added.
...
How do I create a simple 'Hello World' module in Magento?
...ou want to match this url
http://example.com/magento/index.php/helloworld/foo
You will have to have a FooController, which you can do this way :
touch app/code/local/MyCompanyName/HelloWorld/controllers/FooController.php
<?php
class MyCompanyName_HelloWorld_FooController extends Mage_Core_C...
Why aren't python nested functions called closures?
...f printer():
print msg
return printer
printer = make_printer('Foo!')
printer()
When make_printer is called, a new frame is put on the stack with the compiled code for the printer function as a constant and the value of msg as a local. It then creates and returns the function. Because ...
Detecting an undefined object property
...ndefined" on the global object was writeable, and therefore a simple check foo === undefined might behave unexpectedly if it had accidentally been redefined. In modern JavaScript, the property is read-only.
However, in modern JavaScript, "undefined" is not a keyword, and so variables inside functio...
Propagate all arguments in a bash shell script
... you actually wish your parameters to be passed the same.
Observe:
$ cat foo.sh
#!/bin/bash
baz.sh $@
$ cat bar.sh
#!/bin/bash
baz.sh "$@"
$ cat baz.sh
#!/bin/bash
echo Received: $1
echo Received: $2
echo Received: $3
echo Received: $4
$ ./foo.sh first second
Received: first
Received: second
Re...
Best way to initialize (empty) array in PHP
... been noted that initializing a new array is faster if done like this var foo = [] rather than var foo = new Array() for reasons of object creation and instantiation. I wonder whether there are any equivalences in PHP?
...