3. Your First Alef Program

In this chapter, you will build a tiny ticket priority program. It is small enough to understand, but it uses the pieces you need in real Alef code: values, functions, maps, if, and output.

Step 1: Print Text

Create main.alef:


fn main() {
    println("TicketDesk")
}
Run 

alef run main.alef
Output 

TicketDesk

Step 2: Store A Value

Change the file:


fn main() {
    let title = "Checkout timeout"
    println(title)
}

let creates a local value. title is the name. "Checkout timeout" is a string.

Output 

Checkout timeout

Step 3: Use A Function

Functions make behavior reusable.


fn label(id, title) {
    return "{id}: {title}"
}

fn main() {
    println(label("TD-101", "Checkout timeout"))
}
Output 

TD-101: Checkout timeout

Step 4: Make A Decision

Use if when a program needs to choose.


fn priority(plan, blocked) {
    if plan == "enterprise" and blocked {
        return "P0"
    }
    return "P2"
}

fn main() {
    println(priority("enterprise", true))
}
Output 

P0

Step 5: Put Data In A Map

Maps are good for JSON-like data.


fn priority(plan, blocked) {
    if plan == "enterprise" and blocked {
        return "P0"
    }
    return "P2"
}

fn main() {
    let ticket = {
        "id" => "TD-101",
        "title" => "Checkout timeout",
        "plan" => "enterprise",
        "blocked" => true
    }

    let p = priority(ticket["plan"], ticket["blocked"])
    let id = ticket["id"]
    println("{id}: {p}")
}
Output 

TD-101: P0

You now know enough to read the next chapters: