how to write a rule that make the result to be a function of input？

[big91987]

Hi Everyone,
Recently I was working using the egg for quantum gate compiling problem and encountered this scene:
I need the rfs of rule after '=>' be a function of the inputs, in the julia version of egg It's work，like this：

``` julia code ```` (https://github.com/overshiki/SymbolicCircuit.jl/blob/main/src/rule.jl)
commute_rule = @rule a b a::Gate * b::Gate => :($(b) * $(a)) where is_commute(a, b)
cancel_rule = @rule a b a::Gate * b::Gate => One() where is_cancel(a, b)
expand_rule = @rule a a::Gate => expand(a) where is_expand(a)
merge_rule = @rule a b a::Gate * b::Gate => merge(a, b) where is_merge(a, b)

but I can not find A corresponding implementation in this rust version egg，I read the code in tests and found the Analysis Trait maybe work but not very sure （It looks more like a trait for cost calculation method），Is there any solution? Thank you ：）

[big91987]

the julia version egg is Metatheory.jl, we use this julia impl and encounter some performance issue and we want to use the rust version to implement this 。。

[mwillsey]

You might be looking for a dynamic Applier where you can have a right-hand side of rule that executes your own Rust code.

[big91987]

thx a lot! I'll try it