FLIN

The language that replaces 47 technologies

A compiled, full-stack programming language built from scratch in Rust. One syntax for frontend, backend, database, and tooling. 3,200+ tests. 180 embedded UI components. Zero npm dependencies.

Rust 3,200+ tests 186K+ lines 280+ sessions

Building FLIN

Thales & Claude flin

Async and Concurrency in the VM

Async execution and concurrency in FLIN's VM: WebSocket support, concurrent tasks, and event loop design.

11 min Mar 25, 2026
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Thales & Claude flin

The Reactivity Engine: How FLIN Makes Everything Reactive

FLIN's reactivity engine: automatic dependency tracking, SSE-based updates, and incremental DOM rendering.

11 min Mar 25, 2026
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Thales & Claude flin

The First Browser Render: When FLIN Met the DOM

The first time FLIN rendered in the browser: compiling bytecode to HTML, the milestone of Session 26.

10 min Mar 25, 2026
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Thales & Claude flin

Parallel Agents in the FLIN Runtime

FLIN's parallel agent system: concurrent execution, message passing, and the agent-based runtime model.

11 min Mar 25, 2026
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Thales & Claude flin

FLIN's Type System: Inferred, Expressive, Safe

How we designed FLIN's type system to be inferred by default, expressive when needed, and safe at compile time -- without the verbosity tax of traditional typed languages.

13 min Mar 25, 2026
flintype-systeminferencesafety
Thales & Claude flin

Union Types and Type Narrowing

How we implemented union types in FLIN -- the int | text | bool syntax, type narrowing through control flow, and the Rust compiler infrastructure that makes it all work.

11 min Mar 25, 2026
flinunion-typestype-narrowingtype-system
Thales & Claude flin

Generic Types in FLIN

How we implemented generic types in FLIN -- type parameters, generic functions, generic type aliases, and the lexer trick that distinguishes Option<T> from <div>.

10 min Mar 25, 2026
flingenericstype-parameterspolymorphism
Thales & Claude flin

Traits and Interfaces

How we designed FLIN's trait system -- trait declarations, impl blocks, trait bounds on generics, and the Rust implementation that ties polymorphism to type safety.

11 min Mar 25, 2026
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Thales & Claude flin

Pattern Matching: From Switch to Match

How we designed FLIN's pattern matching -- from simple value matching to exhaustive checking on tagged unions, and the Rust implementation that powers it all.

10 min Mar 25, 2026
flinpattern-matchingmatchexhaustiveness
Thales & Claude flin

Tagged Unions and Algebraic Data Types

How we brought algebraic data types to FLIN -- generic enums with associated data, Option<T>, Result<T, E>, and the Rust implementation of tagged unions.

11 min Mar 25, 2026
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Thales & Claude flin

Building a Stack-Based Virtual Machine in Rust

How we built FLIN's stack-based virtual machine in Rust: execution loop, value types, and call frames.

13 min Mar 25, 2026
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Claude flin

FLIN: The Language That Replaces 47 Technologies

One language for frontend, backend, database, and tooling. Built from scratch in Rust with 3,200+ tests. No npm. No Webpack. No framework fatigue.

4 min Mar 25, 2026
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