scaring you

"I have characterized myself recently as a recovering typoholic and a convert to Visual Basic and in my various talks I use the paper on type-indexed rows that I wrote together with Mark Shields as the prime example of how deep you can fall as an addict to static typing.

As many of us undoubtedly do every once in a while, I was egosurfing for “typoholic”; vague hoping it would be a Google wack. However, much to my astonishment the first hit is actually our paper on type-indexed rows (alternatively type in typoholic on the Google homepage and hit “I’m feeling lucky”). That page does not contain the word "typoholic" and until now there were no links pointing to it!

If you ask me, this is pure voodoo. Perhaps I should start wrapping myself in aluminum foil to protect me against the Google mind control waves.
"

Factory and Iterator patterns

Probably I should have posted this somewhere else, like in lambda community, but I know they think of patterns as of stupid struts for clueless "software engineers".

Why would I need a Factory? To do lazy evaluation, right? Build the object when I need it, not all in advance.

Now with Iterator you can do the same, if we imagine an Iterator that keeps only one instance in mind. It returns it when asked, and then stops. Singleton iterator, so to say.

And my question is, for the purpose of lazy evaluation techniques (e.g. streams), would not it make sense to forget about Factories and think of Iterators only?

Scheme streams in Java

See http://mitpress.mit.edu/sicp/full-text/book/book-Z-H-24.html for reference. This book contains the original code in Scheme.

(define (sieve stream)
  (cons-stream
   (stream-car stream)
   (sieve (stream-filter
           (lambda (x)
             (not (divisible? x (stream-car stream))))
           (stream-cdr stream)))))

(define primes (sieve (integers-starting-from 2)))

And below is my Java code (with some questionable features, worth discussing) that implements the same sieve, doing the same trick:

Now, the Java code - I'd rather have it beautified in HTML, but could not find any online tool that would do that... (under cut) ( Read more... )

Дорогие шизофренды (going functional)

Going functional, I just stopped understanding why, in Java, I have to concoct an "object" to pass an obvious dependency - I mean, to pass a function. Instead, have to pass a "Map". There's a big difference between a function and a Map. A Map returns a meager null if the key happens to be absent. All I actually need is a closure that does what I tell it to do. Javascript is so much more convenient! I'm not a typoholic anymore.

превед иссенгапуры

(thanks to jwz