Introduction

Flint is a small programming language and HTTP runtime. You write route handlers in .fl files, HTML-first pages in .flint.html files, or control-first pages in .flint.ui files. The CLI compiles them 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, and native functions for practical work such as HTTP, JSON, strings, math, environment variables, time, and UUIDs.

A Complete Route

This handler responds to GET /hello with plain text:

txt

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

route GET "/hello" -> say_hello

Read it from top to bottom:

Line	Meaning
`say_hello:`	Defines a label the route below can target.
`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.
`route GET "/hello" -> say_hello`	Maps an HTTP route to the handler.

A Complete Page

This page responds to GET / with HTML:

html

@page "/"
<!doctype html>
<h1>Hello from Flint</h1>

Pages can include Flint instructions:

html

@page "/hello"
<%
mov r0, "name"
ncallr r1, http.query, r0
%>
<h1>Hello <%= r1 %></h1>

The page compiler turns this into a normal route module that calls http.html.

What Runs

txt

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

What Makes Flint Different

There are 16 general registers: r0 through r15.
Registers are shared by all functions in a compiled module.
Route files are compiled independently, then registered on one HTTP router.
use "path.fl" inlines shared code before compilation.
JSON is a runtime value, not a string convention.
Server-rendered HTML and UI pages compile into ordinary Flint route handlers.

Learning Path

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

Introduction ​

A Complete Route ​

A Complete Page ​

What Runs ​