Comments URL: https://news.ycombinator.com/item?id=28569945

Points: 2

# Comments: 1

Comments URL: https://news.ycombinator.com/item?id=20677651

Points: 1

# Comments: 0

Consider multitouch. Conventional mouse-desktop thinking orients us to one pointer and a one-point interaction mode. "Normal Users" (aka, the Your Mom archetype) new to the touch experience and to Eliss almost always use a single finger to drag around the screen objects, switching to two only to pinch. But around level 3, the game ramps up in difficulty, and this is when the magic happens. The user starts falling behind. Without asking or thinking about it, nearly every single one of them suddenly starts using their other hand. Nobody told them it would work! These are users terrified of clicking the File menu, because it once ate their Word document. Experimentation has a huge mental inhibition, and yet touch is so intuitive it bypasses the block. I've asked all these users whether they noticed -- and while this isn't rigorous by any degree -- nearly all of them reported they did not. This is magic.

Thank you Steph Thirion, for hours of enjoyment in Eliss as well as a lovely natural experiment in UX.

Comments URL: https://news.ycombinator.com/item?id=5764324

Points: 5

# Comments: 0

// => `45`, because `this.a` is resolved to `window.a`, as `window` is the global variable used as the method context when we call an unbound function (which is stupid (`null` would have been a way better choice, Brandon)).

    var o = { a:13, add:function(b){ return this.a + b; } };
    o.add(42); // => `55`
    var add = o.add;
    add(42); // => `NaN`, because `this.a` is (presumably) `undefined`
    var a = 3;
    add(42); // => `45`, because `this.a` is resolved to `window.a`, as `window` is the global variable used as the method context when we call an unbound function (which is stupid (`null` would have been a way better choice, Brandon)).

The important quality (in my practical understanding) is that a generic function's specialization is decoupled from the object system -- delegating to `x.__iter__()` doesn't require `x` inheriting a method from a parent; the process `iter(x)` uses to delegate might not even require any type information about `x` at all.

In both cases, the key observation is to realize that the meaning of the numbers is more important than the numbers (or how they're calculated, per se). This point is kind of abstract--especially compared to the salient examples in both pieces--but if you're looking to understand why this error is so common, look first to the fact that it's not an error of stupidity or insufficient maths.

You can sometimes avoid a big practical problem (e.g., an avenue to attack your system via diluting meaning ("spam")) by abstractly considering the meaning behind the structures available to you.

Comments URL: https://news.ycombinator.com/item?id=3213025

Points: 3

# Comments: 0

http://www.google.com/insights/search/#cat=0-5&q=cassand...

I added Cassandra, as it's substantially more popular than Riak (whereas HBase is not, and you only get 5 slots).

Comments URL: https://news.ycombinator.com/item?id=2902002

Points: 1

# Comments: 0

Comments URL: https://news.ycombinator.com/item?id=2889680

Points: 2

# Comments: 1

For example, we could force a double-valued transcendental function to float and back for a small loss of precision in normal cases:

    #define sin(d) ((double)sinf(d))

    double i =  10
    --> i    =  10.0000000000
    sin(i)   = -0.5440211109
    sinf(i)  = -0.5440211296
    delta    =  0.0000000187
    
    double i =  0.25
    --> i    =  0.2500000000
    sin(i)   =  0.2474039593
    sinf(i)  =  0.2474039644
    delta    = -0.0000000051
    
    double i = 9999999.999999
    --> i    = 9999999.9999989998
    sin(i)   =  0.4205487007
    sinf(i)  =  0.4205478132
    delta    =  0.0000008875

Another idea: Let's say we know the application relies on rand() to produce the correct distribution for testing, or maybe to generate session keys. Changing the semantics of the RNG won't result in a compiler bug, but it might result in the tests failing to cover all cases, or a horrible security breach.

http://www.oracle.com/technetwork/database/berkeleydb/overvi...

License for server usage is Sleepycat. http://en.wikipedia.org/wiki/Sleepycat_License

http://webcache.googleusercontent.com/search?q=cache:zlciYW0...

Comments URL: https://news.ycombinator.com/item?id=2089070

Points: 5

# Comments: 0