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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...
What is the size of an enum in C?
...ating a set of enum values, but I need each enum value to be 64 bits wide. If I recall correctly, an enum is generally the same size as an int; but I thought I read somewhere that (at least in GCC) the compiler can make the enum any width they need to be to hold their values. So, is it possible to h...
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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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...
What is Java String interning?
...gs will ensure that all strings having same contents share same memory. So if you have list of names where 'john' appears 1000 times, by interning you ensure only one 'john' is actually allocated memory.
This can be useful to reduce memory requirements of your program. But be aware that the cache i...
Loading basic HTML in Node.js
...
I just found one way using the fs library. I'm not certain if it's the cleanest though.
var http = require('http'),
fs = require('fs');
fs.readFile('./index.html', function (err, html) {
if (err) {
throw err;
}
http.createServer(function(request, re...
How to find the port for MS SQL Server 2008?
I am running MS SQL Server 2008 on my local machine. I know that the default port is 1433 but some how it is not listening at this port. The SQL is an Express edition.
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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...
Export a graph to .eps file with R
... a .pdf file (using the 'pdf' function), and it works quite well. However, now I have to export to .eps files.
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