Re: syntax heresy

[Uli Kusterer <witness.of.teachtext@...>]

On Aug 9, 2005, at 13:42:59, Boyko Bantchev wrote:
> >   Don't worry, he's talking about a programming language:
> >
> > http://en.wikipedia.org/wiki/Brainf%2Ack
>
> I know.

 I guessed so, but I was actually trying to console Klaus, who  
seemed to be seeing the mention of brainfuck as an insult. From his  
later replies I suppose he knew the language and still considered it  
an insult. I actually think brainfuck is a very clever and cool  
language. Especially since it is very easy to write a parser,  
compiler and/or interpreter for it. That doesn't keep me from not  
wanting to have to program in it, though ;-)

> But I was actually serious about the preprocessor I described,
> I do use it and find the style of writing convenient.  Making fun is
> ok, but I was hoping to also provoke some exchange of opinions
> on this.  Can't believe that absolutely noone is interested in such
> a discussion.

 I've seen enough people try to write such "language translators"  
using simple search/replace patterns or regular expressions. Most of  
them got pretty far, than realized that they wanted to do more than  
this solution would allow. As you seem to be using the same technique  
(at least that's what some of your statements sounded like to me), I  
didn't really have much hope for this getting anywhere.

 The difference between a Macro processor and a compiler is that a  
preprocessor has a very limited parser. It's usually concerned with  
symbolic constant substitution and conditional compilation, and not  
much else. For that, search and replace works just fine. For anything  
more, you'll typically need a full-blown parser, and once you're  
there, you might as well just replace Lua's parser and get rid of the  
middleman to just deploy to the same byte-code format.

 I personally am from the opposite camp than you are. I prefer  
really verbose and english-like languages. Therefore, I guess you'll  
understand that while I respect the craftsmanship, I'm not really too  
much interested in your translator. :-/ If you wanted to create a new  
parser on top of Lua, though, I might be interested in helping with  
the front end/back end separation, though. After all, that would let  
me replace the parser with one of my own, verbose ones.

> In this respect, could Lua be used as a
> preprocessor to itself?  Especially since Lua can compile &
> execute Lua code?  Perhaps some form of a `syntax
> bootstrapper'?  PL/I, in its time, had a preprocessor that was
> more or less PL/I itself.  But these days preprocessors seem
> not to be in fashion.

 Lua definitely seems powerful enough for me to write a Lua compiler  
in. And an interpreter. Once you have those, you could certainly use  
Lua to compile itself. But IMHO that would hamper Lua's portability.  
ANSI C already has been ported to most platforms, and lua and luac  
compile beautifully that way. Bootstrapping would mean we'd need to  
write native-code compilers for each platform Lua should run on...  
The approach is cool from a technical point of view, but would sadly  
be impractical. Of course, the preprocessor could be written in Lua.

Cheers,
-- M. Uli Kusterer
http://www.zathras.de