radiant

A focused, type-safe HTTP router for Gleam on BEAM.

Built on a prefix tree with specificity-based priority, no global state, no macros.

gleam add radiant

Quick start

import gleam/int
import radiant

pub const user_id = radiant.int("id")

pub fn router() -> radiant.Router {
  radiant.new()
  |> radiant.get("/", fn(_req) { radiant.ok("hello") })
  |> radiant.get1("/users/<id:int>", user_id, fn(_req, id) {
    radiant.json("{\"id\":" <> int.to_string(id) <> "}")
  })
  |> radiant.scope("/api/v1", fn(r) {
    r |> radiant.post("/items", create_item)
  })
}

get1 hands the parsed Int directly to the handler — no let assert, no int.parse.

Why Radiant?

Gleam’s native routing is case wisp.path_segments(req) — great for small apps. Radiant adds:

Features

• Prefix tree: O(1) literal lookup; cost grows with path depth, not route count.
• Specificity priority: Literal > <id:int> > <name:string> > *wildcard, regardless of registration order.
• Typed routes (get1–get6): handlers receive parsed Int/String values directly.
• Type-safe context: pass data through middlewares via Key(a) — no Dynamic, no manual decoding.
• Automatic 405 + HEAD: correct Allow header and HEAD→GET fallback built in.
• Startup validations: wildcard position, duplicate capture names, and capture ambiguity checked at registration, not at request time.
• Swappable static server: FileSystem interface works with simplifile or any IO library.
• Testing helpers: synthetic requests and fluent assertions — no running server needed.

Documentation

• Quickstart — first working server in 5 minutes
• Basic usage — routing, params, context, response helpers, query params
• Routing reference — patterns, priority, scope/mount, reverse routing
• Middleware — built-in middleware and custom middleware patterns
• Testing — test helpers and assertions
• Integrations — Mist and Wisp

Non-goals

Radiant does not provide: template rendering, sessions, cookies, authentication, or WebSockets. Use the underlying server (Mist) or a full framework (Wisp) directly for those.

Development

gleam test    # Run the test suite
gleam dev     # Start the demo server on :4000