## Roy - Literate Roy

2012-01-01

— I added some literate programming support to Roy. You can write Markdown files with an extension of `.lroy`

and the `roy`

executable will accept them.

I've also written a shell script that will run it through Pandoc to give you nice-looking HTML output, using Kevin Burke's Markdown.css:

The above was generated using the following Markdown:

```
% Roy - Babylonian Square Root
This is a Markdown file. It's also literate Roy code!
We're going to define a `sqrt` function using the
[Babylonian method][] for approximation.
let sqrt n =
Making a good initial guess helps reduce the amount of
iterations until convergence. One method is to find the
highest-bit (`b`) and use `2^(b/2)`.
let highestBit n i =
if (1 << i) > n then
i
else
highestBit n (i + 1)
let guess = 1 << ((highestBit n 1) / 2)
Iteratively average the guess and the number divided by the guess
until convergence with a cut-off of 0.001. The guessing is started
from the initial value, calculated above.
let nextGuess g =
if (Math.abs (g - (n / g))) < 0.001 then
g
else
nextGuess ((g + (n / g)) / 2)
nextGuess guess
Now we can calculate the square root of 314 and print it.
console.log (sqrt 314)
We should get an answer of around 17.720.
[Babylonian method]: http://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method
```

Happy New Year!

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