Strength is a category theoretical property which is known to be boring - every `Monad` in `Hask` (and similarly `Scal`) satisfies it. The question arises - what about it's dual, Costrength? What would a Costrong Comonad look like? Is it interesting? It turns out the answer is no - every `Comonad` in `Hask`/`Scal` is `Costrong`. In this post I'll provide a brief tutorial on `Comonads` and show why every `Comonad` is also Costrong. You do NOT need to know much category theory to follow this post, but some familiarity with the everyday programming of Monads will be helpful.

## How to return an array of generic type, or "cannot find class tag for element type T"

I was recently writing some Scala code, and I wanted to return an array of generic type:

```class Foo[+T] {
def someArray(size: Int): Array[T] = {
val result = new Array[T](size)
...
result
}
}
```

This did not make Scala happy:

`[info] Compiling 1 Scala source to /home/stucchio/src/breeze/math …`

## Why a pro/con list is 75% as good as your fancy machine learning algorithm

I'm currently dating two lovely women, Svetlana and Elise. Unfortunately continuing to date both of them is unsustainable so I must choose one.

In order to make such a choice, I wish to construct a ranking function - a function which takes as input the characteristics of a woman and returns …

## Asymptotics of Evan Miller's Bayesian A/B formula

Earlier this year I published a blog post about a Baysian decision rule for choosing between two variations, each with a potentially different conversion rate. Later Evan Miller wrote a blog post computing an exact formula for evaluating it, rather than approximating the integral numerically. In this post I'm going …

## Easy Evaluation of Decision Rules in Bayesian A/B testing

Earlier this year I published a blog post about a Baysian decision rule (now dead link, but VWO now uses this for A/B testing and tech docs are here) for choosing between two variations, each with a potentially different conversion rate. The basic idea of the decision rule is …

## Optimizing Ad Placement with Julia and Maximum Likelihood

Estimating the conversion rate of an advertisement placed in a fixed slot on a webpage is a well studied problem, and one I've discussed at length. For those who haven't seen, here are some slides which might help.

In the real world, however, it's not always the case that an …

## Mosh - ssh for a bad connection

I'm currently located in India. Most of my servers are in the US. Due to my location, I have to deal with crappy wifi connections (in the past hour I switched from NETGEAR1 to NETGEAR2), high latency, disconnections and the like. Often I'm stuck tethered to my phone, which occasionally …