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How to play with Control.Monad.Writer in haskell?
...Writer
ghci> let logNumber x = writer (x, ["Got number: " ++ show x])
Now logNumber is a function that creates writers. I can ask for its type:
ghci> :t logNumber
logNumber :: (Show a, MonadWriter [String] m) => a -> m a
Which tells me that the inferred type is not a function that r...
How do I change the string representation of a Python class? [duplicate]
...
The closest equivalent to Java's toString is to implement __str__ for your class. Put this in your class definition:
def __str__(self):
return "foo"
You may also want to implement __repr__ to aid in debugging.
See here for more information:
Special Method Names - Basic Cu...
error LNK2019: 无法解析的外部符号_socket，该符号在函数 中被引用 - c++1...
1>NetClient.obj : error LNK2019: 无法解析的外部符号 _closesocket@4，该符号在函数 _main 中被引用
1>NetClient.obj : error LNK2019: 无法解析的外部符号 _inet_ntoa@4，该符号在函数 _main 中被引用
1>NetClient.obj : error LNK2019: 无法解析的外部符...
Ruby: How to turn a hash into HTTP parameters?
...re, considering all the major Ruby web frameworks are built on top of Rack now.
– iain
May 16 '13 at 13:10
@EdRuder Ac...
Zip lists in Python
...ip(a, b, c)
In [4]: len(result[0])
Out[4]: 3
Of course, this won't work if the lists were empty to start with.
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I want to get the type of a variable at runtime
...stance, may want not to know what is the type of the variable, but to know if the type of the value is some specific type, such as this:
val x: Any = 5
def f[T](v: T) = v match {
case _: Int => "Int"
case _: String => "String"
case _ => "Unknown"
}
f(x)
Here it doesn't m...
How do you crash a JVM?
...g the 4 Gb memory limit under the 32-bit versions (we generally use 64-bit now).
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How to detect orientation change?
...on while using the camera with AVFoundation, and found that the didRotate (now deprecated) & willTransition methods were unreliable for my needs. Using the notification posted by David did work, but is not current for Swift 3.x/4.x.
Swift 4.2
The notification name has been changed.
The closure...
How to delete a file or folder?
..._path.mkdir()
file_path = directory_path / 'file'
file_path.touch()
and now:
>>> file_path.is_file()
True
Now let's delete them. First the file:
>>> file_path.unlink() # remove file
>>> file_path.is_file()
False
>>> file_path.exists()
False
We can use...
How do I run a single test with Nose in Pylons
...ler should work, where the file is named test_controller.py.
To run a specific test class and method use a path of the form module.path:ClassNameInFile.method_name, that is, with a colon separating the module/file path and the objects within the file. module.path is the relative path to the file (e...