58 lines
2.5 KiB
Markdown
58 lines
2.5 KiB
Markdown
# Type Level Programming
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This repository contains a collection of examples demonstrating various type-level programming patterns in Rust, Go, and TypeScript.
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The goal of these examples is to show how to leverage the type system of a language to enforce invariants at compile-time, reducing the need for runtime checks and making the code more robust and self-documenting.
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## Repository Structure
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The examples are organized by language and complexity.
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### Rust
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The Rust examples demonstrate a progression of state management for a `CredentialManager`:
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- **[01-problem](./01-problem)**: The initial problem where state is not managed, allowing operations in any order.
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- **[02-runtime-check](./02-runtime-check)**: Adding runtime checks (e.g., `bool` flags) to ensure operations are performed in the correct state.
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- **[03-builder-pattern](./03-builder-pattern)**: Using separate structs to represent different states, ensuring state transitions are enforced at compile-time.
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- **[04-typestate](./04-typestate)**: A classic implementation of the Typestate pattern using generics and `PhantomData` to track state.
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### Go
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- **[05-typestate-go-structs](./05-typestate-go-structs)**: Implementing state transitions in Go using separate structs for each state.
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- **[06-typestate-go-interfaces](./06-typestate-go-interfaces)**: Using interfaces to restrict the available methods based on the current state of the object.
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### TypeScript
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- **[07-typestate-ts](./07-typestate-ts)**: Implementing the Typestate pattern in TypeScript using `this` type parameters to restrict method calls.
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- **[08-type-mapping](./08-type-mapping)**: Mapping enum values (like opcodes) to specific argument types for type-safe messaging.
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- **[09-type-programming](./09-type-programming)**: Advanced recursive type parsing to extract parameters from URL string literals at compile-time.
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## Getting Started
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### Rust
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You can run the Rust examples using Cargo from the root directory:
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```bash
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# Example: Running the typestate example
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cargo run -p 04-typestate
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```
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### Go
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The Go examples can be run using the Go CLI:
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```bash
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go run ./05-typestate-go-structs
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```
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### TypeScript
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The TypeScript examples are best viewed in an IDE (like VS Code) to see the type errors and completions. You can also run them using `ts-node`:
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```bash
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npx ts-node 07-typestate-ts/main.ts
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```
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## Sources
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- https://www.emoses.org/posts/resolver-resolved-pattern/
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- https://farazdagi.com/posts/2024-04-07-typestate-pattern/
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- https://youtu.be/_ccDqRTx-JU
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- https://type-level-typescript.com/
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