The term “referential transparency” comes from analytical philosophy, the branch of philosophy that analyzes natural language constructs, statements and arguments based on the methods of logic and mathematics. In other words, it is the closest subject outside computer science to what we call programming language semantics. The philosopher Willard Quine was responsible for initiating the … Read more
A Y-combinator is a “functional” (a function that operates on other functions) that enables recursion, when you can’t refer to the function from within itself. In computer-science theory, it generalizes recursion, abstracting its implementation, and thereby separating it from the actual work of the function in question. The benefit of not needing a compile-time name … Read more
Well macros don’t directly expand recursively, but there are ways we can work around this. The easiest way of doing recursion in the preprocessor is to use a deferred expression. A deferred expression is an expression that requires more scans to fully expand: #define EMPTY() #define DEFER(id) id EMPTY() #define OBSTRUCT(…) __VA_ARGS__ DEFER(EMPTY)() #define EXPAND(…) … Read more
Here’s the briefest explanation: A Turing Complete system means a system in which a program can be written that will find an answer (although with no guarantees regarding runtime or memory). So, if somebody says “my new thing is Turing Complete” that means in principle (although often not in practice) it could be used to … Read more
Cohesion refers to what the class (or module) can do. Low cohesion would mean that the class does a great variety of actions – it is broad, unfocused on what it should do. High cohesion means that the class is focused on what it should be doing, i.e. only methods relating to the intention of … Read more
Statistics. The de facto standard for testing RNGs is the Diehard suite (originally available at http://stat.fsu.edu/pub/diehard). Alternatively, the Ent program provides tests that are simpler to interpret but less comprehensive. As for shuffling algorithms, use a well-known algorithm such as Fisher-Yates (a.k.a “Knuth Shuffle”). The shuffle will be uniformly random so long as the underlying … Read more
Yes, it is possible, we can generate regexes from examples (text -> desired extractions). This is a working online tool which does the job: http://regex.inginf.units.it/ Regex Generator++ online tool generates a regex from provided examples using a GP search algorithm. The GP algorithm is driven by a multiobjective fitness which leads to higher performance and … Read more
Generally speaking, the approach I use in this kind of situation is to have both an interface and an abstract class. The interfaces defines, well, the interface. The abstract class is merely a helper. You really can’t go wrong with this approach. Interfaces give you the flexibility to change implementation. Abstract classes give you boilerplate … Read more
The reason why you can access “out of scope” or “free” variables in ECMAscript is the such called Scope chain. The scope chain is a special property from each Execution context. As mentioned several times before, a context object looks at least like: [[scope]] Variable / Activation Object “this” context value each time you access … Read more
A transaction is a unit of work that you want to treat as “a whole.” It has to either happen in full or not at all. A classical example is transferring money from one bank account to another. To do that you have first to withdraw the amount from the source account, and then deposit … Read more