Well, as far as the language is concerned – yes, both functions are called. If you rewrote the function to this: public boolean isTrue() { return isBTrue() || isATrue(); } then the second function will not be called, if the first is true. But this is short-circuit evaluation, not lazy evaluation. Lazy evaluation case would … Read more
Have you ever written an AI? Isn’t it annoying that you have to thread pruning information (e.g. maximum depth, the minimum cost of an adjacent branch, or other such information) through the tree traversal function? This means you have to write a new tree traversal every time you want to improve your AI. That’s dumb. … Read more
Yes, but there is one nice trick: if you have lazy value, and during first time evaluation it will get an exception, next time you’ll try to access it will try to re-evaluate itself. Here is example: scala> import io.Source import io.Source scala> class Test { | lazy val foo = Source.fromFile(“./bar.txt”).getLines | } defined … Read more
First and foremost, please do not think of greediness and laziness in regex as means of getting the longest/shortest match. “Greedy” and “lazy” terms only pertain to the rightmost character a pattern can match, it does not have any impact on the leftmost one. When you use a lazy quantifier, it will guarantee that the … Read more
The difference between them is, that a val is executed when it is defined whereas a lazy val is executed when it is accessed the first time. scala> val x = { println(“x”); 15 } x x: Int = 15 scala> lazy val y = { println(“y”); 13 } y: Int = <lazy> scala> x … Read more
this will delete cache public static void deleteCache(Context context) { try { File dir = context.getCacheDir(); if (dir != null && dir.isDirectory()) { deleteDir(dir); } } catch (Exception e) {} } public static boolean deleteDir(File dir) { if (dir != null && dir.isDirectory()) { String[] children = dir.list(); for (int i = 0; i < … Read more
Yes, Python evaluates boolean conditions lazily. The docs say, The expression x and y first evaluates x; if x is false, its value is returned; otherwise, y is evaluated and the resulting value is returned. The expression x or y first evaluates x; if x is true, its value is returned; otherwise, y is evaluated … Read more
Closest thing I can find to an ‘official’ mention of PHP’s short-circuit implementation: http://php.net/manual/en/language.operators.logical.php
The body of a class or an object is the primary constructor. A constructor, like a method, is a sequence of statements that are executed in order — to do anything else, it would have to be a very different language. I’m pretty sure you wouldn’t like for Scala to execute the statements of your … Read more
doall is all you need. Just because the seq has type LazySeq doesn’t mean it has pending evaluation. Lazy seqs cache their results, so all you need to do is walk the lazy seq once (as doall does) in order to force it all, and thus render it non-lazy. seq does not force the entire … Read more