The goal of this post is to start a centralised discussion on the definition of intents and to provide the necessary context for it.
Definitions
Intents
Users initiate a state transition on the blockchain by submitting their intent. Intents are representations of user preferences that shape the initiated state transition. They are invariant across all possible state transitions, meaning that no matter what transaction gets constructed, the user’s intent will be satisfied by it. Solvers are the actors who receive user intents and match them together, constructing transactions.
Unbalanced and balanced transactions
Transactions are data structures that solvers construct to satisfy users’ intents. They are designed in the resource model, in which state transitions are represented as consumed (input) and created (output) resources - atomic data units. A transaction have to be valid and balanced to be executed. Unbalanced transactions can be composed into balanced transactions.
Balance
Each resource has a resource kind and an unsigned numeric value called quantity. When a resource is being consumed, its quantity is assumed to be negative, and when a resource is being created, the quantity is assumed to be positive. A transaction balance is the sum of the resource quantities per each resource type. A transaction is called balanced when for each resource type, the balance of the transaction equals to zero[1].
Are intents unbalanced transactions?
Well, yes and no. Intents can be represented as unbalanced transactions, but are not equivalent to them. Let’s take a closer look.
I. Intents = unbalanced transactions
When the user knows exactly what they want, they simply produce an unbalanced transaction that creates the asset they want. The solver’s goal is to find another unbalanced transaction that consumes the desired asset. Such a transaction, composed with the original one, will result in a balanced transaction.
II. Intents \neq transactions
Resource logic
Every resource has a predicate encoded into it that expresses the rules on which the resource can be consumed and created. This predicate is called a resource logic.
Intents = predicates
In the case when a user doesn’t know exactly what they want[2], they can encode all possible options that would satisfy them in a predicate. The resource logic then would require this predicate to be satisfied.
To allow that behaviour a special kind of resources is used[3], a logic of which states that this resource can be consumed only if the associated intent predicate is satisfied. The user would create a resource of that kind at the beginning of interaction and consume it at the end. Having this resource consumed in the transaction proves that the intent was satisfied.
Here, the intent is a predicate encoded in a resource, and resources are consumed and created in transactions. So, the intent is carried by a transaction but is not equal to it.
So..what are intents?
In the first section I described intents abstractly, and in the next section described two different (complementary) ways[4] to express them in the Anoma model. To start the discussion, I propose to use a variation of the definition from the first section as the definition:
Intents are representations of user preferences that shape the initiated state transition. They are invariant across all possible state transitions, meaning that no matter what transaction gets constructed, the user’s intent will be satisfied by it.
the transaction balance is checked against the balancing value. For transactions fully within the shielded pool the value is 0. ↩︎
it can also be used when the user knows what they want, but using just unbalanced transactions might be cheaper in this case ↩︎
it isn’t actually special ↩︎
this overview is not exhaustive, and there are other ways to express intents ↩︎