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

#024 -- How the VM Executes Views

How FLIN's VM executes views: from bytecode opcodes to HTML rendering with reactive attribute binding.

11 min Mar 26, 2026
flinviewsrenderinghtml +3
Thales & Claude flin

#025 -- The Complete FLIN Opcode Reference

The complete FLIN opcode reference: arithmetic, control flow, entity, view, and closure instructions.

17 min Mar 26, 2026
flinopcodesbytecodereference +2
Thales & Claude flin

#026 -- Hot Module Reload in 42ms

FLIN's hot module reload: file changes compiled and in the browser in under 50ms, with state preserved.

11 min Mar 26, 2026
flinhot-reloadhmrdeveloper-experience +2
Thales & Claude flin

#027 -- 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 26, 2026
flinasyncconcurrencywebsocket +2
Thales & Claude flin

#028 -- 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 26, 2026
flinreactivitysseincremental +2
Thales & Claude flin

#029 -- 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 26, 2026
flinbrowserrenderhtml +2
Thales & Claude flin

#030 -- Parallel Agents in the FLIN Runtime

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

11 min Mar 26, 2026
flinagentsconcurrencyparallel +2
Thales & Claude flin

#031 -- 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 26, 2026
flintype-systeminferencesafety
Thales & Claude flin

#032 -- 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 26, 2026
flinunion-typestype-narrowingtype-system
Thales & Claude flin

#033 -- 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 26, 2026
flingenericstype-parameterspolymorphism
Thales & Claude flin

#038 -- The Pipeline Operator: Functional Composition in FLIN

How we implemented the pipeline operator in FLIN -- the |> syntax for functional composition, its parser transformation to function calls, and the developer experience it unlocks.

10 min Mar 26, 2026
flinpipelinefunctionalcomposition
Thales & Claude flin

#044 -- Labeled Loops and Or-Patterns

How we implemented labeled loops and or-patterns in FLIN -- breaking from outer loops by name, combining match arms with pipe syntax, and the compiler changes that support them.

11 min Mar 26, 2026
flinlabeled-loopsor-patternscontrol-flow