Introduction

Flint is a small programming language and HTTP runtime. You write HTTP route modules in .fl files and server-rendered UI pages in .flint.ui files. The CLI compiles both forms to bytecode and serves them with a fresh virtual machine per request.

The language is assembly-like on purpose: every line does one visible thing. There are registers, labels, jumps, calls, sections, and native functions for practical work such as HTTP, JSON, strings, math, environment variables, time, UUIDs, and UI rendering.

A Complete Route

This handler responds to GET /hello with plain text:

section .route
    GET "/hello" -> say_hello

section .text
say_hello:
    mov r0, "Hello!"
    ncall http.text, r0
    ret

Read it from top to bottom:

Line	Meaning
section .route	Starts route declarations.
GET "/hello" -> say_hello	Maps GET /hello to a global label.
section .text	Starts executable code.
say_hello:	Defines the route handler label.
mov r0, "Hello!"	Stores a string in register r0.
ncall http.text, r0	Sets the response body to plain text.
ret	Returns from the handler.

A Complete UI Page

UI pages live under pages/ and end with .flint.ui. They use sections too:

section .route
    GET "/"

section .render
    window "Home"
        text "Hello from Flint UI"
        card "Actions"
            btn "Open API", "/hello"
        end
    end

The page compiler turns this into a normal .fl route module that builds an HTML accumulator with ui.* natives and returns it with http.html.

What Runs

.fl route modules and .flint.ui pages
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      v
preprocessor / parser / page compiler
      |
      v
bytecode program plus route metadata
      |
      v
fresh VM per HTTP request
      |
      v
HTTP response

What Makes Flint Different

• There are 16 registers: r0 through r15.
• Registers are shared by all functions in a compiled module.
• Every .fl source file must use section blocks.
• Route files are compiled independently, then registered on one HTTP router.
• use "path.fl" inlines shared .fl code before compilation.
• @use "path.fl" at the top of a .flint.ui page includes shared .fl code into the generated route module.
• JSON is a runtime value, not a string convention.
• UI pages compile into ordinary Flint route handlers.

Learning Path

1. Install and create a project: Installation.
2. Build a few endpoints: First API.
3. Render a page: UI Pages.
4. Learn the VM model: Core Concepts.
5. Split a larger app: Project Structure.
6. Keep the references nearby: Language Syntax, Instruction Set, and Native Functions.