Getting started

  1. Install
  2. Your first composition
  3. What just happened
  4. Next steps

Install 

go get github.com/go-via/via

Via targets a current Go toolchain and has no build step, code generation, or template files.

Your first composition

A composition is a Go struct. Reactive state is a typed field, actions are methods, and View renders it.

package main

import (
    "github.com/go-via/via"
    "github.com/go-via/via/h"
    "github.com/go-via/via/on"
)

type Counter struct {
    Hits via.StateTabNum[int]
    Step via.SignalNum[int] `via:"step,init=1"`
}

func (c *Counter) Inc(ctx *via.Ctx) {
    c.Hits.Op(ctx).Add(c.Step.Read(ctx))
}

func (c *Counter) View(ctx *via.CtxR) h.H {
    return h.Div(
        h.P(h.Text("Count: "), c.Hits.Text(ctx)),
        h.Input(h.Type("number"), c.Step.Bind()),
        h.Button(h.Text("+"), on.Click(c.Inc)),
    )
}

func main() {
    app := via.New()
    via.Mount[Counter](app, "/")
    app.Start() // binds :3000, wires SIGINT/SIGTERM to a graceful Shutdown
}

go run .
# open http://localhost:3000

No template files. No build step. No hand-written JavaScript. on.Click(c.Inc) is a typed method reference: the handler signature is compile-checked and a misspelled method name won’t build. It must be a real bound method — a closure or plain function type-checks but panics at the first render, since it has no name to route to.

What just happened

  • Step is a SignalNum[int] — a client signal. The <input> it binds to (c.Step.Bind()) mutates it in the browser with no round-trip.
  • Hits is a StateTabNum[int] — server-only, per-tab. It changes only through the Inc action.
  • Inc runs server-side, reads the current client Step, and updates Hits. The next flush diffs the View and ships a targeted DOM patch over the tab’s SSE stream — c.Hits.Text(ctx) updates in place.

The whole client/server split is visible in the field types. See Reactive state for the full model.

Next steps

  • Reactive state — the four shapes, scopes, and typed ops.
  • Actions & lifecycle — events, hooks, streaming.
  • Rendering (h) — the HTML DSL.
  • Testing — drive compositions over HTTP with vt.
  • Browse internal/examples/ in the repo (go run ./internal/examples/counter).