I want to code in Scheme

But I don't really know how to write idiomatic code. Is anyone here willing to rewrite some of my python code, so I can see how it's done?

Also, what is the code-tag on this board?

Here are a few things I'm interested in specifically:

How do I attach metadata to a function that can be read without calling the function. (but don't prevent the function to be called in the usual way.)

By using for i, (op, jtype) in enumerate(itertools.product(numops, jnumtypes)): I avoid nesting two loops and adding a counter-variable. What do lisp-people use here?

For pretty-printing I make sure that the opcodes have a proper name, and that certain ints are printing together with the role they have (like ConstantIndexOperand). Is there a way to define how certain objects are serialized/pretty-printed in scheme?