egg VS SumTypes.jl

Maybe program optimization?

https://egraphs-good.github.io/

For semantic analyzers, check out egg and egglog. They're custom data structures for representing compiler rewrite rules in a non-destructive way.

E-graphs are pretty awesome, and worth keeping in your back pocket. They're like union-find structures, except they also maintain congruence relations (i.e. if `x` and `y` are in the same set, then `f(x)` and `f(y)` must likewise be in the same set).

https://egraphs-good.github.io/

(Incidentally, union-find structures are also great to know about. But they're not exactly "new".)

I would add that Equality saturation/E-graphs has become quite a hot topic recently, since their POPL21 paper, with workshops dedicated to applications of e-graphs. They have even recently been added to Cranelift as an IR for optimizations.

Egraphs solve the rewrite ordering problem quite nicely. https://egraphs-good.github.io/

Note that one solution to this problem is to use equality saturation (which, coincidentally, has a great implementation in rust!).

Have you thought about trying to parallelize e-graphs? This way you can do a bunch of rewrite rules in parallel and then extract your desired graph at the end instead of having conflicts.

I think the equality saturation papers are a good start. A good start is egg. They have a presentation, a research paper and code you can play with. I think ultimately you want to translate arithmetic operations into logical operation that can be understood by the fpga. So I think it would be good to research how adders and multipliers are implemented in logic and ultimately include equalities between adders/multipliers with their logical counterpart. Note the this translation also depends on the representations of your numbers and their bit width.

For rewriting, you may also find interesing equality saturation: https://egraphs-good.github.io/

An interesting aspect of sum types (what Rust calls enums) is that you can implement them in the language as a library if you have real unions, but not vice-versa.

Here's my example of sum types being implemented in julia as a regular package: https://github.com/MasonProtter/SumTypes.jl

> Pattern matching

MLStyle.jl [1] is quite nice for this and has been around for a while.

> Tagged, closed unions

These are less general than 'real' unions and can be implemented using them. E.g. SumTypes.jl [2] has some macros to make it a bit more convenient to define them, it could use some other quality of life features though.

[1] https://thautwarm.github.io/MLStyle.jl/latest/syntax/pattern...

[2] https://github.com/MasonProtter/SumTypes.jl