Re: Looking for volunteers for XL

On Nov 27 2011, 11:24 pm, "BartC" <b...@freeuk.com> wrote:
> A self-extensible language sounds like a good idea and might well
> work. I admit I've never used one ...


Really?
AFAIK you tried Seed7 a little bit (Thank you four your
fannkuch-redux benchmark program). So you tied an extensible
language without noticing that it is extensible. :-)


> (although I did play with designing
> one once, then gave up),


The trick is: You need to restrict the possibilities somehow to
"reasonable" features. I know that this depends on the point of
view...


> and have no idea what is and isn't possible;
> could you create a language that has C syntax for example, then add in
> a few Cobol-like statements or APL expressions?


Funny, such things were the original idea, which lead to Seed7.
Later I found that some restrictions really make sense. BTW:
Seed7 could do this, when APL operators are restricted to ASCII. :-)
The braces of C would conflict with existing braces in the
predefined Seed7 language (Seed7 uses them to define set literals).
So some of the existing Seed7 definitions need to be omitted, which
I did for the following example. The example defines a
C if-statement:


$ include "seed7x_05.s7i";


# Define the syntax of a simple C if-statment:
$ syntax expr: .if.().{.().} is -> 25;


# Define the semantic of a simple C if-statement:
const proc: if (in boolean: cond) {
                              (in proc: statement)
                        } is func
                            begin
                                if cond then
                                    statement;
                                end if;
                            end func;


const proc: main is func
    begin
        # Use the C if-statement:
        if (TRUE) {
            writeln("okay");
        }
    end func;


I left out COBOL and APL, but you should see the principle.
BTW: I don't think that such a brutal mix of language features
(C, COBOL, APL) makes sense.


> Or is the syntax it's
> capable of rather more limited?


Seed7 is not overengineered, and other extensible languages should
also avoid this pitfall.




Greetings Thomas Mertes


--
Seed7 Homepage: http://seed7.sourceforge.net
Seed7 - The extensible programming language: User defined statements
and operators, abstract data types, templates without special
syntax, OO with interfaces and multiple dispatch, statically typed,
interpreted or compiled, portable, runs under linux/unix/windows.

Return to the comp.compilers page.
Search the comp.compilers archives again.