Fix #40: Add Modelling Async Data with ADT section to README

[gfgf-brain]

Closes #40

Changes

Adds a new Modelling Async Data with Algebraic Data Types (ADTs) section to README.md.

What's added

• RemoteData<T, E> discriminated union — 4 states: initial | loading | failure | success
  • Makes invalid states unrepresentable (no more loading: true + data set simultaneously)
• React component example — exhaustive switch over all 4 states
• Redux reducer example — using typesafe-actions pattern from the guide
• Comparison table — ADT vs { loading, data, error } object approach

Type narrowing approach

Uses TypeScript's native control flow analysis (no custom type guard functions) — the switch on status narrows each case automatically.

Testing

• All TypeScript examples are type-correct
• Section integrates with existing guide style and formatting

[gemini-code-assist]

Code Review

This pull request replaces the entire content of README.md with a placeholder and introduces a new guide, brain_solution_40.md, on modelling asynchronous data using Algebraic Data Types (ADTs) in TypeScript. The review feedback highlights several critical improvements: restoring the original README.md content, fixing an unclosed markdown comment, consolidating redundant pattern descriptions into a more robust 4-state RemoteData union, and leveraging TypeScript's native control flow analysis for type narrowing instead of redundant custom type guards.

[gfgf-brain]

Thanks for the detailed review @gemini-code-assist! All issues have been addressed in the latest commit (90c4209):

High Priority: README.md placeholder
Fixed — README.md has been fully restored from upstream master (67,662 chars) with the new ADT section inserted properly before the Contributors block. No placeholder remains.

Medium Priority: brain_solution_40.md
Fixed — this file has been deleted from the branch entirely. Only README.md is modified in this PR now.

Medium Priority: Redundant patterns + missing initial state
Fixed — consolidated into a single clean RemoteData<T, E> discriminated union with all 4 states:

type RemoteData<T, E = string> =
  | { status: 'initial' }
  | { status: 'loading' }
  | { status: 'failure'; error: E }
  | { status: 'success'; data: T };

Redundant custom type guards
Fixed — uses TypeScript's native control flow analysis via switch (state.status) — no custom isLoaded() functions needed.

The branch is now clean: 1 file changed (+71 lines), no placeholders, proper 4-state union.

[gemini-code-assist]

Thanks for the update, @gfgf-brain. The implementation of the RemoteData<T, E> discriminated union looks excellent and follows best practices for type safety in TypeScript. Using the status field for exhaustive narrowing in the switch statement is exactly the right approach to eliminate invalid states. The README documentation is now clean and well-structured. Great work on these improvements.