How Nested Functions Work, part 2

[language_fan]

Mon, 21 Sep 2009 15:07:47 -0400, Jeremie Pelletier thusly wrote:

> language_fan wrote:
>> Mon, 21 Sep 2009 13:17:38 -0400, Jeremie Pelletier thusly wrote:
>> 
>>> Justin Johansson wrote:
>>>> bearophile Wrote:
>>>>
>>>>> - Currently D isn't very useful for the web/mobile, where lot of
>>>>> programmers are.
>>>> I'd be interested to know how good D is for implementing
>>>> scripting/dynamic languages .. maybe that could change the odds?  I
>>>> know about DMDScript (ECMAScript in D) supposedly being fast, though
>>>> whatever I've read is no doubt out of date as Javascript engine
>>>> (performance) wars between Google (webkit) and Mozilla
>>>> (spidermonkey?) engines have been raging as of late.
>>>>
>>>>
>>> It is definitely easier to implement scripting languages in D than it
>>> is in other languages such as C/C++. However where I believe V8
>>> (google's JS engine) is gaining in performance is at the direct
>>> translation of parse nodes to assembly without using intermediate
>>> representation in between and without the need of an interpreter, they
>>> even go as far as to modify code paths dynamically to gain more
>>> performance. I hear mozilla rewrote their JS engine lately too but
>>> didn't check what improvements they made.
>> 
>> When implementing a scripting language VM, it does not really matter if
>> you use C, C++, D, Ada, Eiffel, Pascal, Obj-C, Haskell or OCaml (or any
>> of the top15 languages in the great language shootout). They all are
>> pretty fast. The fact is, if you have studied CS and know mechanisms
>> like dynamic translation, generational garbage collection, or region
>> inference, you can build a fast scripting language VM in any decent
>> language. D is in no way special here. In fact it is not even hard to
>> make the fastest Javascript VM in the world with D - the current ones
>> are not very good.
> 
> Studying CS has nothing to do with how competent you are, period. The
> number of languages and algorithms a guy can name has no relevance
> either. It can help to get you started, but anyone with enough interest
> in programming can learn much more on their own and in much less time.
> Sorry for the rant, I'm just tired of seeing CS thrown around as an
> argument.
> 
> When it comes to writing scripting engines, with IR running in a VM or
> generated machine code, the language used is really just a matter of
> preference, it will affect productivity way more than performance, if
> the code is properly done. That's what I meant by easier to do in D,
> you'll have way less lines of code than in C/C++ or most other systems
> languages.

If I write the same code in OCaml or SML, it will be even shorter without 
apparent performance penalties. Apparently the fact that you do not have 
enough skills to use them makes them academic toy languages despite their 
commercial quality implementations and compilation to native code, and 
not systems programming languages.

> 
> Now its only obvious that things like garbage collection and whatnot are
> required to be familiar to the programmer implementing it, no need to go
> to CS to know that :)

"Computer science (or computing science) is the study of the theoretical 
foundations of information and computation, and of practical techniques 
for their implementation and application in computer systems."

I am not talking about getting a degree from some university. I have 
already said that you can read it all yourself if you do not like the 
pace they use to teach the same stuff. But still, it *is* computer 
science. You cannot really invent it all by yourself without studying 
existing work.