# wheel-utils

I wanted to write a fast, straight-forward, extensible fizzbuzz program. This is a small utility I wrote to do it. It can generate simple wheels that you can use if you have a recurring sequence (like fizzbuzz). 

## documentation

## usage

Put it in your site-dir. Then you should be able to:

    (use-modules (wheel-utils wheel))

### every-n in value [n]
    
	(every-n-in "fizz" 3) -> '(#f #f "fizz")
    (every-n-in "bugz" 2 3) -> (#f "bugz" #f)

This is a procedure used to generate proto-wheels that are merged together into a larger proto-wheel using generate-wheel.

### generate-wheel combine proto-wheels ...
Combines proto-wheels using the combine procedure and returns a new, larger proto-wheel:

    (define fizz '(every-n-in "fizz" 3))
	(define buzz '(every-n-in "buzz" 5))
	(define (combine . args)
	  (let ((args (filter values args)))
	    (if (null? args)
		  #f
		  (apply string-append args))))
    (define proto-wheel (generate-wheel combine fizz buzz))
	
Proto-wheel can now be converted to a circular list or a vector depending on your needs. Most people will probably convert it to a circular-list, but wheels _can_ grow prohibitively large and using a vector might fit more into the cpu cache. The fizzbuzz wheel is just 15 elements long. A fizz-buzz-bar (where bar is instead of multiples of 7) is 105 elements long. fizz-buzz-bar-quux (quux instead of 11) means 1155 elements.

## How fast was your fizzbuzz
How does our fizzbuzz fare against a naive implementation? Using the code in example.scm (both procedures generate lists of fizzy and buzzy goodness) these are my numbers:

    scheme@(guile-user)> ,time (car (regular-fizzbuzz 10000000))
    $26 = 1
    ;; 1.161756s real time, 1.242915s run time.  0.314005s spent in GC.
    scheme@(guile-user)> ,time (car (wheel-fizzbuzz 10000000))
    $27 = 1
    ;; 0.528079s real time, 0.614268s run time.  0.312021s spent in GC.

It can of course be done faster, but not necessarily in such a simple way. The wheel version is also trivially extensible if you are unsure about your future fizzbuzzing needs.

## Todo

It would be fun to be able to generate step wheels, like for example a prime wheel where we can just skip large parts of the number line. 

## Licence

a simplified ISC. Non of that big-letter stuff matters in my jurisdiction, so I removed it. You may use it under regular ISC if you please.