There is an objective benefit to using `constructs-to-c` and that is something you mention in your original comment: you generate a single binary file containing all of your business logic, thus avoiding running a "fully interpreted" app in production.
In order to determine if it gives a performance boost to your particular rules engine, you should test it out and benchmark it with something you'd consider a "real world" example.
> you should test it out and benchmark it with something you'd consider a "real world" example.
I thought that you might have specific experience with "real world" applications, thus my question.
The CLIPS "Advanced Programming Guide" states in secion 11.1, that "...compiles all of the constructs [..] into a single executable and reduces the size of the executable image. A run-time program will not run any faster than a program loaded using the load or bload commands"; so as far as I understand it, the code is still interpreted (i.e. not affected by the translation to C).
Good find in the apg! That thing is a wealth of info. It look like contructs-to-c wouldn't make things faster, but would instead reduce the compiled code size.
If I'm understanding your meaning, you mean "interpreted" in a sense that it translates to C code, and C code is interpreted and translated into machine code. Is that accurate?
It's possible that you and I are referring to different things when we use the word "interpreted." When I think "interpreted" in the context of computer programming, I'm thinking in terms of interpreted-at-runtime programming languages like Ruby, Python, and CLIPS before you use `constructs-to-c`. In my mind, using `constructs-to-c` changes this from an "interpreted" to a "compiled" language in that the expert system you write in CLIPS code is its own language with its own data structures, algorithms, and DSL. When you use `constructs-to-c`, you "compile" your application using the programming language of your expert system, thus it is no longer interpreted at run time.
> you mean "interpreted" in a sense that it translates to C code, and C code is interpreted and translated into machine code
No, I mean that the Lisp variant of CLIPS is a pure interpreter, (assumingly) not even threaded, and (certainly) no JIT. The "constructs-to-c" feature apparently doesn't change anything to that, i.e. even in the "translated to C" version of the CLIPS code it is still interpreted.
> I'm thinking in terms of interpreted-at-runtime programming languages like Ruby, Python
Me too.
> and CLIPS before you use `constructs-to-c` ... changes this from an "interpreted" to a "compiled" language
Didn't find evidence for this so far; as far as I understand it's still the same interpreter.
I'm sorry, but I still think I'm not sure what you mean by interpreter. I hope you don't mind if I press further, but I'm very much enjoying this deep dive into the CLIPS C API with you.
When you compile your code including the c files generated by the constructs-to-c command, you must update the main.c file as well as the makefile that ships with CLIPS. During that update, there are a few things you must do:
1. add the generated c files to the makefile
2. you remove the function calls in the main.c file that cause CLIPS to capture STDIN and STDOUT. That is: you remove one layer of abstraction that sits between your rules and i/o streams.
3. you remove the generic CreateEnvironment function call in main.c and replace it with InitCImage_1, a function that calls CreateRuntimeEnvironment.
CreateRuntimeEnvironment differs from CreateEnvironment because you are able to pass in pre-built:
Which are your rules engine constructs represented in C.
In addition to these four things, CreateRuntimeEnvironment passes in functions the user may have defined as UserDefinedFunctions (UDFs) in C. This is a more direct path than having CLIPS first interpret CLIPS rules like `(defrule foo =>)` and then translate them into these C representations.
I didn't find the time yet to check the details in the source code, so I can only speculate from experience with other VMs. As it seems from your description the constructs-to-c version removes the interactive part (REPL) which is apparently not needed in stand-alone applications. But that's unrelated to the question in which format the code/rule-base is kept and executed. The C files could embed both a text or a byte code version of the CLIPS code/rule-base, and the interpreter is implemented in C anyway. But I think I have to check in the (generated) source code (the architecture manual doesn't even mention the term "interpreter"). For some years I was thinking about using CLIPS for algorithmic music composition, but it might be too slow; seems to be not trivial to get reliable performance figures.
> For some years I was thinking about using CLIPS for algorithmic music composition
This is a great use case! I'd be interested in seeing what you come up with.
> in which format the code/rule-base is kept
When you use constructs-to-c, the generated C files represent your rules engine constructs as pointers to pointers of CLIPSLexeme, CLIPSFloat, CLIPSInteger, and CLIPSBitMap structs. It does not store it as the raw clips code fed into the interpreter. You can later use functions like `save-facts` to generate the rules in CLIPS syntax based on these pointers to pointers of structs.
Ok, then it's aparently the intermediate representation (what the parser feeds to the evaluator), which makes sense. The evaluator doesn't care, whether it comes from the parser or from constructs-to-c generated code.
> Ok, then it's aparently the intermediate representation (what the parser feeds to the evaluator), which makes sense. The evaluator doesn't care, whether it comes from the parser or from constructs-to-c generated code.
> I thought that you might have specific experience with "real world" applications, thus my question.
As to this point: I don't at present have "real world" experience writing CLIPS. My experience thus far has been entirely research-driven based on observations I've made in "real world" scenarios.
If you want to read about some other people who have used CLIPS in real world scenarios, here's the most comprehensive HN thread to date so far on the subject:
Thanks. I was also in the discussion. When CLIPS is used as an expert system shell, then performance comparisons are pretty restricted. But since you have seemed to use it more for "indexing" and "caching", which is a domain shared by other interpreters used for the web, a performance comparison seems more feasible, especially if you already have implemented such features with other interpreters as well.
> you have seemed to use it more for "indexing" and "caching", which is a domain shared by other interpreters used for the web
That's the idea! I think CLIPS is a good framework for a generic run-loop (or `while` loop). If you can conceptualize your app as such, you can reap the benefits inherent in the rete algorithm within your application logic.
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> But does this actually give a speed-up?
There is an objective benefit to using `constructs-to-c` and that is something you mention in your original comment: you generate a single binary file containing all of your business logic, thus avoiding running a "fully interpreted" app in production.
In order to determine if it gives a performance boost to your particular rules engine, you should test it out and benchmark it with something you'd consider a "real world" example.
I thought that you might have specific experience with "real world" applications, thus my question.
The CLIPS "Advanced Programming Guide" states in secion 11.1, that "...compiles all of the constructs [..] into a single executable and reduces the size of the executable image. A run-time program will not run any faster than a program loaded using the load or bload commands"; so as far as I understand it, the code is still interpreted (i.e. not affected by the translation to C).
If I'm understanding your meaning, you mean "interpreted" in a sense that it translates to C code, and C code is interpreted and translated into machine code. Is that accurate?
It's possible that you and I are referring to different things when we use the word "interpreted." When I think "interpreted" in the context of computer programming, I'm thinking in terms of interpreted-at-runtime programming languages like Ruby, Python, and CLIPS before you use `constructs-to-c`. In my mind, using `constructs-to-c` changes this from an "interpreted" to a "compiled" language in that the expert system you write in CLIPS code is its own language with its own data structures, algorithms, and DSL. When you use `constructs-to-c`, you "compile" your application using the programming language of your expert system, thus it is no longer interpreted at run time.
No, I mean that the Lisp variant of CLIPS is a pure interpreter, (assumingly) not even threaded, and (certainly) no JIT. The "constructs-to-c" feature apparently doesn't change anything to that, i.e. even in the "translated to C" version of the CLIPS code it is still interpreted.
> I'm thinking in terms of interpreted-at-runtime programming languages like Ruby, Python
Me too.
> and CLIPS before you use `constructs-to-c` ... changes this from an "interpreted" to a "compiled" language
Didn't find evidence for this so far; as far as I understand it's still the same interpreter.
When you compile your code including the c files generated by the constructs-to-c command, you must update the main.c file as well as the makefile that ships with CLIPS. During that update, there are a few things you must do:
1. add the generated c files to the makefile 2. you remove the function calls in the main.c file that cause CLIPS to capture STDIN and STDOUT. That is: you remove one layer of abstraction that sits between your rules and i/o streams. 3. you remove the generic CreateEnvironment function call in main.c and replace it with InitCImage_1, a function that calls CreateRuntimeEnvironment.
CreateRuntimeEnvironment differs from CreateEnvironment because you are able to pass in pre-built:
1. symbolTable 2. floatTable 3. integerTable 4. bitmapTable
Which are your rules engine constructs represented in C.
In addition to these four things, CreateRuntimeEnvironment passes in functions the user may have defined as UserDefinedFunctions (UDFs) in C. This is a more direct path than having CLIPS first interpret CLIPS rules like `(defrule foo =>)` and then translate them into these C representations.
This is a great use case! I'd be interested in seeing what you come up with.
> in which format the code/rule-base is kept
When you use constructs-to-c, the generated C files represent your rules engine constructs as pointers to pointers of CLIPSLexeme, CLIPSFloat, CLIPSInteger, and CLIPSBitMap structs. It does not store it as the raw clips code fed into the interpreter. You can later use functions like `save-facts` to generate the rules in CLIPS syntax based on these pointers to pointers of structs.
Concerning the use case, an SBCL based solution would likely perform much better, though the Scheme VM of Common Music (https://ccrma.stanford.edu/software/snd/snd/s7.html) is also purely interpreted.
Precisely!
As to this point: I don't at present have "real world" experience writing CLIPS. My experience thus far has been entirely research-driven based on observations I've made in "real world" scenarios.
If you want to read about some other people who have used CLIPS in real world scenarios, here's the most comprehensive HN thread to date so far on the subject:
https://news.ycombinator.com/item?id=40201729 - 30 days ago
One in particular that stands out to me is the usage of CLIPS in MTG:Arena, a real-time web-based card game with and arguably large amount of rules.
> you have seemed to use it more for "indexing" and "caching", which is a domain shared by other interpreters used for the web
That's the idea! I think CLIPS is a good framework for a generic run-loop (or `while` loop). If you can conceptualize your app as such, you can reap the benefits inherent in the rete algorithm within your application logic.
To see what I mean, take a look at the tcp server in the CLIPSockets repo: https://github.com/mrryanjohnston/CLIPSockets/blob/6.4.1/exa...
UPDATE: I edited the link to point to the 6.4.1 tag version of the repo. The `main` branch is using the latest (7.x) from CLIPS svn as the base.
UPDATE2: I edited my previous comment to specify that it is a tcp server, not an http server.