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Vertex

Your first Vertex program

This page assumes you have already installed Vertex and vertex --version prints a version.

Hello, Vertex

Section titled “Hello, Vertex”

Create a file called hello.vtx:

debug "hello, vertex!"

Run it:

$ vertex run hello.vtx
hello, vertex!

That is it. No main function, no class wrapper, no sfdx-project.json, no deploy. Vertex executes top-level statements in order, top to bottom.

debug is the output function

Section titled “debug is the output function”

debug is the only way to produce observable output. It is an expression: it evaluates its argument, prints it, and returns the value so you can inspect mid-pipeline.

debug "hello"
debug 42
debug true


let sum = debug 1 + 2      // prints 3, then binds sum = 3

Bindings

Section titled “Bindings”
let name = "Alice"
let age  = 30


debug "Hello, ${name}! You are ${age}."

All bindings are immutable by default. If you need to reassign:

mutable let counter = 0
counter = counter + 1
counter = counter + 1
debug counter       // 2

The visible mutable keyword is deliberate. Reassignment is possible but it stands out. See Bindings.

Doing something useful

Section titled “Doing something useful”

Here is a complete program that pitches several of the ideas the tour will cover in more depth:

fn label(age: Int): String {
    if age < 18 { "minor" } else { "adult" }
}


fn describe(name: String, age: Int): String {
    "${name} is ${label(age)} (age ${age})"
}


debug describe("Alice", 30)
debug describe("Bob", 15)

Run it:

$ vertex run greet.vtx
Alice is adult (age 30)
Bob is minor (age 15)

What just happened

Section titled “What just happened”
  • No deploy. Vertex ran your code locally via its built-in JIT.
  • Compile-time guarantees. The types of name, age, and the return of label were all checked before anything ran.
  • Millisecond feedback. No org, no build step, no waiting.

Next

Section titled “Next”