In Theory: Self-Correcting Software

How Plang enables self correcting software

This article explores Plang, an intent-based programming language designed to interpret natural language. For more information, visit plang.is or take your first steps

In Plang, you can bind events to goals(functions) and steps(line of code), a feature that proves incredibly powerful.

Let's consider a scenario: you want to ensure that a user is logged in before they can call a function in the /admin route.

No problem in Plang:

Events
- before any goal in /admin, call AuthenticateUser

AuthenticateUser
- select id as userId from users where %Identity% and role='admin', return 1
- if %userId% is empty then
    - show error "You don't have permission"

And there you have it—authentication is solved in just 4 lines of code.

How does this translate to self-correcting software?

Self-Correcting Software

Let's say I'm making a POST request to a service:

CreateUserAsExample
- post https://example.org/api/createuser
    {name:"%name%", }

At some point in future, the service changes and requires us to provide email, it will return an error message such as this:

 {"error":"You need to provide Email (%email%)"}.

Now, let's bind an event to all errors that happen in step.

Events
- on error on any step, call SelfCorrect

SelfCorrect
- [llm] system: fix this plang code...
    user:%!error.Message%
    write to %code%
...

Here, we've instructed the LLM to fix the Plang code. If we ask the current Plang assistant to handle this scenario, it would give you an updated code

CreateUserAsExample
- post https://example.org/api/createuser
    {name:"%name%", email:%email%}

Now, plang can save the new code to its path, build and run the code.

- write %code% to %!error.Goal.RelativePath%
- run terminal plang build
- retry step

The full code for the event is then

Events
- on error on any step, call SelfCorrect

SelfCorrect
- [llm] system: fix this plang code...
    user:%!error.Message%
    write to %code%
- write %code% to %!error.Goal.RelativePath%
- run terminal plang build
- retry step

Self correcting software in few lines of code. Plang is just awesome!

But What if the Email is Still Empty?

Yes, the %email% field might still be empty, because the email might be coming from some user interface.

In this case, you need to traverse up the call stack and fix the previous goal. Once one issue is resolved, the same principle applies to the next one. It's just a matter of engineering.

Part 2

Read up on part 2 here

More Information

If Plang is interesting to you, you should dig a bit deeper:

• Basic concepts and lessons

• Simple Todo example is a good start

• Check out the GitHub repo

• Meet up on Discord to discuss or get help

• Chat with the Plang Assistant