While a block is just a piece of code that can be composed by statements and declarations but nothing else, a closure is a real first-class object, a real variable that has a block as its value. The main difference is that a block simply groups instructions together (for example the body of a while … Read more
Context Free is a concept from language theory that has important implications in parser implementation. A Context Free Language can be described by a Context Free Grammar, which is one in which all rules have a single non-terminal symbol at the left of the arrow: X→δ That simple restriction allows X to be substituted by … Read more
There’s a simple ad hoc proof for this. Since you can build a Turing complete language using strictly iterative structures and a Turing complete language using only recursive structures, then the two are therefore equivalent.
Pattern Recursion With recursive patterns, you have a form of recursive descent matching. This is fine for a variety of problems, but once you want to actually do recursive descent parsing, you need to insert capture groups here and there, and it is awkward to recover the full parse structure in this way. Damian Conway’s … Read more
The most obvious problem is with function overriding. Let’s say have two classes A and B, both of which define a method doSomething. Now you define a third class C, which inherits from both A and B, but you don’t override the doSomething method. When the compiler seed this code… C c = new C(); … Read more