Nice Inline Syntax for DSLs

[Russell Lewis]

Knud Soerensen wrote:
> On Fri, 16 Feb 2007 16:35:46 -0700, Russell Lewis wrote:
> 
>> Originally posted in digitalmars.d.announce.  I reposted here when I 
>> realized my mistake.
>>
>> We have been talking about using string imports and code mixins and 
>> their applicability for domain-specific languages.  But the current 
>> design requires either that we wrap the whole sub-language as a string, 
>> or we store it in another file so that we can use string imports.  But 
>> what if we allowed there to be some simple syntax which allowed us to 
>> say, "Here at the top is D code; below is the DSL."  How about something 
>> like:
>>
>>      import my_dsl_compiler;
>>      mixin(MyDSLCompiler!(import_rest_of_this_file));
>>      FIRST_LINE_OF_MY_DSL
>>
>> or
>>
>>      import my_dsl_compiler;
>>      int main(char[][] argv) {
>>          // this line resolves to a lot of variable declarations
>>          // and functions, including a my_dsl_main()
>>          mixin MyDSLCompiler!(import_rest_of_this_file));
>>          return my_dsl_main(argv);
>>      }
>>      FIRST_LINE_OF_MY_DSL
>>
>> Sort of the idea is that whenever the compiler hits a line that includes 
>> some special keyword (in the above example, it is 
>> import_rest_of_this_file), it keeps on to the end of the current 
>> declaration, treating it as D code.  The rest is assumed to be string 
>> data which is imported into the D code above.
>>
>> Think of it like a shebang line in a script, which documents how the 
>> rest of the code is to be handled.
>>
>> Russ
> 
> Well, we already have asm as a dsl.
> Why not use a similar syntax like:
> 
> dslname 
> {
> ...
> }
> 
> We just need a way to tell the compiler which passer to use for dslname.

Sure, you can already do that...but with double quotes.  The reason that 
I think that double quotes, or brackets, are unsatisfying is because 
then those tokens become unusable inside the DSL.  I'm looking for a 
format where the DSL can use any grammar whatsoever, without any need 
for escape sequences or workarounds.