Question about how compilers work Is it possible to generate example source code from an AST node and its corresponding lexer rules?

That's partly how some linters and transpilers work!

oh, yes. that makes sense. can you think of a project whose source code is easier to study?

You can quite easily write your own babel plugins, that could eg. replace strings and numbers with random values.

I guess I’ll look at babel since you mentioned it

Let me know how it goes!

yes, that would be nicer since, in that case, the code is actually more meaningful

Was recently thinking about something similar; how you could autogen UI from data, given meta info of eg. how often + in what context a user would like to access it, and partly what components goes together with each other and what kind of data.

the use case I have in mind is a quick reference for a language. this would serve as an easy reminder for the syntax of a specific AST node

Niiice! Context dependent learnxinyminutes.com!

yes. learnxinyminutes is a source of inspiration

https://svelte.dev/ describes itself as "a compile step that happens when you build your app" ... and is all about generating UI code; so perhaps that's somewhat relevant to your generating a UI ideas?

It is :) Looking to go one step deeper with a custom realtime offline first decentralized graph database with binary data streaming using wasm with rust, builtin, created from a structural declarative language, supporting new UI paradigm(s) (infinite non-euclidean zoom + scroll canvas/space with fluid structure, vs the status quo of plain documents) (see webgpu), while being fully editable and having powerful action history for free, etc etc

I don’t know enough about svelte to tell I realize that what I’m thinking about is basically a modal editor. I’ll have to think if what I have in mind is actually practical

IDK if you are looking for the more "formal" side of this but, I'm reminded of these projects that I had at the bottom of my bookmarks: https://baturin.org/tools/bnfgen/ https://lcamtuf.coredump.cx/afl/ This kind of technique is used in fuzz testing quite a bit. If you think about formal FSM/Automata theory, the normal way we use a FSM is to feed a string and see if it gets the end state (that's what a parser does). You can also run a FSM in reverse to generate random strings from the grammar. The algorithm is usually something like: Start at the starting state, pick a random node, spit out the string that would match that node, pick the next random node, continue until you get to the finish state. Typically you have a way to backtrack out if you end up in an invalid node. Invalid nodes represent parse errors, so you would fail with an error if you were just reading some user input, but since you are generating your own string, the program can rewind out of the bad state.

thanks, Ray. I’ll look into them. I’ve heard of Automata Theory, but I don’t know more about it