Tokens

[MartinMinkov]

Description

Adds custom token and token symbol support in SnarkyJS. This PR adds several helper functions for interacting with custom token ids and token symbols. Additionally adds token id and token symbol to the account type to enable querying the local ledger in SnarkyJS tests. Finally, this PR adds a test script for token and token symbol functionality.

These OCaml changes are needed for o1-labs/o1js#273

Tested

Implemented a JS test script and ran with succession.

[mitschabaude]

awesome!

[mitschabaude]

actually, one ask: could you bump the snarkyjs submodule to the tip of your token PR so we can run it against CI?

[mitschabaude]

I think we need to cover the case where pk and token represent variables, see comments I'll add on the other PR. possibly cover that in a separate function custom_token_id_checked. so that both can have the same interface (pk: PublicKey, token: Field) => Field, I think probably this should return a Field as well

[mitschabaude]

There's probably something like Mina_base.Account_id.Checked.derive_token_id in the code base that we can use

[MartinMinkov]

Got it! Added support for a Checked version, mind taking a look if the new implementation is correct?

[mitschabaude]

looks good except for the two comments!

[mitschabaude]

using var_of_t is wrong because it's only possible if the variable has been converted to a value first, which is what the public_key function does. The forced converting to a value that public_key does only works inside the prover, or if the pk is a constant, but not when compiling the circuit.

We want to preserve the same underlying variables that pk contains (two field elements; possibly variables) and convert them to a Public_key.Compressed.var in an in-snark way. This is code that I got to type-check that I think achieves that:

  let public_key_checked (pk : public_key) :
      Signature_lib.Public_key.Compressed.var =
    let x = pk##.g##.x##.value in
    let y = pk##.g##.y##.value in
    Signature_lib.Public_key.compress_var (x, y) |> Impl.run_checked

(although I'm unsure what run_checked means.. but it has the right type signature :D)

[MartinMinkov]

Got it! I changed the implementation and removed the use of var_of_t. The code snippet type checks and seems to pass existing test cases 👍

[mitschabaude]

same applies here about public_key + var_of_t not being the approach we want

[MartinMinkov]

Changed implementation 👍

[MartinMinkov]

This feels super hacky, does this work? I need a way to convert a Mina_base.Token_id.Checked.t to a Field.t. This type checks but I'm pretty sure the logic is wrong. If there is a better way, can someone advise how to do so?

cc @mitschabaude @bkase

[mitschabaude]

I think this is the right approach 👍🏻 Would've done the same

[mitschabaude]

LGTM!