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How is this fibonacci-function memoized?
...mechanism in Haskell is by-need: when a value is needed, it is calculated, and kept ready in case it is asked for again. If we define some list, xs=[0..] and later ask for its 100th element, xs!!99, the 100th slot in the list gets "fleshed out", holding the number 99 now, ready for next access.
Th...
SLF4J: Failed to load class “org.slf4j.impl.StaticLoggerBinder”
My application is to be deployed on both tcServer and WebSphere 6.1. This application uses ehCache and so requires slf4j as a dependency.
As a result I've added the slf4j-api.jar (1.6) jar to my war file bundle.
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How are the points in CSS specificity calculated
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Pekka's answer is practically correct, and probably the best way to think about the issue.
However, as many have already pointed out, the W3C CSS recommendation states that "Concatenating the three numbers a-b-c (in a number system with a large base) gives the sp...
How to remove a key from Hash and get the remaining hash in Ruby/Rails?
... your five-minutes-of-editing are up, you can always copy, delete, modify, and repost a comment.
– iconoclast
May 13 at 23:17
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Unpacking, extended unpacking and nested extended unpacking
...lain with a few examples. Since you're talking about evaluating these "by hand," I'll suggest some simple substitution rules. Basically, you might find it easier to understand an expression if all the iterables are formatted in the same way.
For the purposes of unpacking only, the following substit...
Reorder levels of a factor without changing order of values
I have data frame with some numerical variables and some categorical factor variables. The order of levels for those factors is not the way I want them to be.
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Merging: Hg/Git vs. SVN
I often read that Hg (and Git and...) are better at merging than SVN but I have never seen practical examples of where Hg/Git can merge something where SVN fails (or where SVN needs manual intervention). Could you post a few step-by-step lists of branch/modify/commit/...-operations that show where S...
valueOf() vs. toString() in Javascript
In Javascript every object has a valueOf() and toString() method. I would have thought that the toString() method got invoked whenever a string conversion is called for, but apparently it is trumped by valueOf().
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MySQL: @variable vs. variable. What's the difference?
...are loosely typed variables that may be initialized somewhere in a session and keep their value until the session ends.
They are prepended with an @ sign, like this: @var
You can initialize this variable with a SET statement or inside a query:
SET @var = 1
SELECT @var2 := 2
When you develop a stor...
Convert RGB to RGBA over white
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Take the lowest color component, and convert that to an alpha value. Then scale the color components by subtracting the lowest, and dividing by the alpha value.
Example:
152 converts to an alpha value of (255 - 152) / 255 ~ 0.404
152 scales using (152 - 1...