Action types (#191)

<!-- ps-id: 6cc3715d-71d8-406a-81ca-b2bd1d22b1e5 -->

Author: freesig

crates/node-types/src/action.rs

@@ -0,0 +1,23 @@
+//! # Action
+//!
+//! Actions use predicates to generate solutions.
+
+use essential_types::{PredicateAddress, Value};
+
+/// Actions represent are used as the input to solve a predicate
+/// and generate a [`Solution`](essential_types::Solution).
+pub struct Action {
+    /// The predicate that will be solved by this action.
+    pub predicate_to_solve: PredicateAddress,
+    /// The inputs to the predicate.
+    pub inputs: Vec<Value>,
+}
+
+/// An atomic unordered set of actions.
+/// These all occur at the same time.
+/// It is invalid for the solutions generated
+/// by these actions to mutate the same keys.
+pub struct ActionSet {
+    /// An unordered set of actions.
+    pub actions: Vec<Action>,
+}

crates/node-types/src/lib.rs

@@ -14,6 +14,7 @@ use essential_types::{
 };
 use serde::{Deserialize, Serialize};
 
+pub mod action;
 pub mod block;
 
 /// Wrappers around tokio's `watch` channel for notifying of new blocks.