How Nested Functions Work, part 1

[language_fan]

Mon, 31 Aug 2009 10:37:29 -0700, Walter Bright thusly wrote:

> language_fan wrote:
>> This seems more like an advertisement of D than practical new
>> information for compiler construction. Nesting functions is the basic
>> feature of functional languages. Moreover even procedural Algol based
>> languages such as Pascal have always supported them, too.
> 
> But not C, C++, Java, etc., so quite a lot of programmers have little
> experience with them, and even less understanding.

Most programmers I know don't use those languages, but then again I'm 
part of some minority.

> 
>> This information is also
>> taught in basic university level compiler courses.
> 
> I bet only a tiny fraction of programmers have taken university compiler
> classes. (Also, they were not covered in compiler classes I took.)
> Consider also that the Java JVM doesn't support static links, and last I
> heard the .NET IL didn't, either.

Ok. We were taught that. We basically built a naive Pascal compiler. 

> 
>> Now that I checked what wikipedia had to say to the matter, it also
>> seemed to mention D. Apparently 'c-like syntax' plus 'advanced feature
>> <foo>' always equals 'innovation'.
> 
> 
> Nested functions aren't innovative; they just are apparently lacking in
> many other popular languages, and seem to confuse a lot of people. If
> you google it, you'll find there's a lot of programmer confusion about
> them. Hence an article as to how they work is in order.

For what it's worth, they also seem somewhat buggy in D. Hopefully 
writing the articles motivates fixing those issues :) For example one 
can't call symbols before their declaration on non-global scope.

> 
> In part 2, I'll cover innovative things D does with nested functions.

Ok.