Write Miden assembly for P2ID and P2IDR scripts

[bobbinth]

We should define some set of "well-known" scripts which user could use to transfer assets between their accounts. Two of the simplest such scripts could be:

• Pay to account ID (P2ID).
• Pay to account ID with recall (P2IDR).

These scripts are described in detail below.

Pay to account ID

This script can be used when a note is intended to deposit all of its assets into a specific account. The pseudocode for this script looks as follows:

begin
  assert(account.get_id() == note.inputs[0])
  for a in note.assets
    account.receive_asset(a)
  end 
end

The script assumes that a note comes with a single input which contains ID of the recipient's account.

Pay to account ID with recall

This script can be used when a note is intended to deposit all of its assets into a specific account within some period. If this time expires, another user (presumably the send of the note) will be able to claim all of the note's assets. The pseudocode for this script looks as follows:

begin
  if chain.get_block_height() > note.inputs[0]
    assert(account.get_id() == note.inputs[1] || account.get_id() == note.inputs[2])
  else
    assert(account.get_id() == note.inputs[1])
  end
  
  for a in note.assets
    account.receive_asset(a)
  end
end

The script assumes that a note comes with the following inputs:

• input[0] contains block height after which the note can be reclaimed by the sender.
• input[1] contains the recipient's account ID.
• input[2] contains the sender's account ID.

Required procedures

These scripts require the following kernel procedures to exist:

Procedure	Description	Context
get account ID	Returns ID of the account in the current transaction.	account, note
get note assets	Returns all assets in the current note.	note
get note inputs	Returns all inputs for the current note	note
get block height	Returns current block height for the transaction.	note, account

They also assume that the recipient's and sender's accounts expose receive_assets procedure which can be used to deposit a single asset into the account's vault.