[kwlug-disc] Modern way of doing Lex/Yacc

[William Park]

I'm not tied to C.  Yes, "domain specific language".  Input data would 
come from users.  If the data is "passive", then I can require well 
known format (eg. JSON).  I run the parser library, then do the business 
logic.
Eg.
     - read from sensor and append it to file or upload to URL.
     - post amount to this account and that account.

In reality, data doesn't stay "passive" for long.  Soon, they want 
conditional, loop, function, etc.
Eg.
     - if this, then do something.
     - do job #10 to job #20.

How do you express these in JSON format?  Maybe
     "cooling": {
	"temperature_set_to" : 25,
	"exec" : "air_conditioner.exe"
     },
     "heating": {
         "temperature_set_to" : 15,
	"exec" : "furnace.exe"
     }

I don't want to write, test, and debug parsers.  I want to concentrate 
on business logic.  That's why I asked.

I mean, this kind of thing is everywhere:
     - Every printer run its own command interpreter.
     - Awk, Sed, Shell are specific interpreters for line texts.
     - bc, dc are calculator interpreter.
     - Even systemd unit file is descriptive script, which systemd 
parses and executes.

They all have their own business logic, but also they all run parser at 
the front.


On 2022-06-22 07:45, Doug Moen wrote:
> Since you mention Lex/Yacc/Flex/Bison, do you specifically require this to work in the C language, or are you open to using a more modern/expressive programming language?
> 
> It sounds like you want to create a "domain specific language" (DSL). Is this DSL going to be used only by the developer (inside the application code), or is it supposed to be used by users (to configure/customize the application)?
> 
> Doug.
> 
> On Tue, Jun 21, 2022, at 11:37 PM, William Park via kwlug-disc wrote:
>> To Computer Science guys,
>>
>> You come across a situation that calls for little "embedded interpreter"
>> solution.
>>       - You can use already existing embedded interpreter like Tcl or
>> Lua.  But, these bring their own baggages.
>>       - Or, you can use Lex/Yacc (or Flex/Bison) solution which you
>> studied in school.  For simple situation, this may be the way to go.
>>
>> But, I'm curious.  Is there something more modern?  Something that
>> leverages 40 years of collective experience in software development.
>> Something more than "state machine", but less than full "interpreter".
>>
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