Nexum

What is Nexum

Nexum generates fine-grained DOM updates at compile time using Nim's macro system. No virtual DOM. No diffing algorithm. Just precise, signal-driven mutations emitted directly from your templates.

The same component code compiles to both a C server binary emitting HTML strings and a JS client bundle mounting real DOM.

See It In Action

Nexum templates look like HTML but compile to zero-overhead DOM operations.

let count = signal(0)

proc Counter(): auto =
  buildHtml:
    button(
      onclick = proc(ev: Event) = count.set(count() + 1)
    ): "Clicked " & $count() & " times"

let name = signal("")

proc Greeting(): auto =
  buildHtml:
    input(
      type = "text",
      oninput = proc(ev: Event) =
        name.set($ev.target.value)
    )
    p: "Hello, " & $name()

let show = signal(true)

proc Conditional(): auto =
  buildHtml:
    if show():
      p: "Visible!"
    else:
      p: "Hidden"
    for i in 1..3:
      li: $i

Under The Hood

Three stages. Three layers. One source file. Two compiled outputs.

The Pipeline

The Stack

The parser transforms the buildHtml DSL into an intermediate representation. The analyzer detects dynamic text, attributes, events, and islands. Backend-specific codegen emits either DOM creation code (JS) or fast string-building code (C). Components marked with @island are emitted with hydration markers so the client only rehydrates the interactive parts.

The Numbers

Compile-time codegen eliminates the runtime overhead that other frameworks carry.

Get Started

nimble install nexum

proc greeting(): auto =
  buildHtml:
    h2: "Hello, Nexum"

echo greeting()  # → 
Hello, Nexum