feat: initialize Kurdistan SDK - independent fork of Polkadot SDK

docs/sdk/src/reference_docs/blockchain_state_machines.rs

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+//! # State Transition Function
+//!
+//! This document briefly explains how in the context of Substrate-based blockchains, we view the
+//! blockchain as a **decentralized state transition function**.
+//!
+//! Recall that a blockchain's main purpose is to help a permissionless set of entities to agree on
+//! a shared data-set, and how it evolves. This is called the **State**, also referred to as
+//! "onchain" data, or *Storage* in the context of FRAME. The state is where the account balance of
+//! each user is, for example, stored, and there is a canonical version of it that everyone agrees
+//! upon.
+//!
+//! Then, recall that a typical blockchain system will alter its state through execution of blocks.
+//! *The component that dictates how this state alteration can happen is called the state transition
+//! function*.
+#![doc = simple_mermaid::mermaid!("../../../mermaid/stf_simple.mmd")]
+//!
+//! In Substrate-based blockchains, the state transition function is called the *Runtime*. This is
+//! explained further in [`crate::reference_docs::wasm_meta_protocol`].
+//!
+//! With this in mind, we can paint a complete picture of a blockchain as a state machine:
+#![doc = simple_mermaid::mermaid!("../../../mermaid/stf.mmd")]
+//!
+//! In essence, the state of the blockchain at block N is the outcome of applying the state
+//! transition function to the previous state, and the current block as input. This can be
+//! mathematically represented as:
+//!
+//! ```math
+//! STF = F(State_N, Block_N) -> State_{N+1}
+//! ```