Datastructures on Miden

[hackaugusto]

It may be nice to have data structure as part of the standard library, this discussion is to defined which and what their data layout would look like. One possibility is not not have any data structures on the standard library and delegate this to each compiler / programming language, this however has the downside of making it difficult to interoperate on different languages. One initial suggestion is to follow the same layout used by Solidity

This was moved from: #626

[hackaugusto]

At the stdlib level, we are currently planning to have at least 2 data structures defined:

    A Sparse Merkle tree which maps 256-bit values to 256-bit values (or actually 4 field elements to 4 field elements).
    A Merkle Mountain Range - which is an append-only accumulator.

We need these two for the rollup. Beyond these, we haven't really defined anything but strings and dynamic arrays could be good future candidates.

One other comment: I think these types of discussions would better go into the Discussions section rather than Issues.

Comment from @bobbinth #626 (comment)