Functions

function add(num a, num b) -> num {
  return a + b
}

function greet(str name, str greeting = "Hello") -> str {
  return greeting + ", " + name + "!"
}

async function loadUser(num id) -> obj {
  const res = await fetch("/api/users/" + id)
  return await res.json()
}

• Parameters may have types and defaults. Parameter syntax name: type also works.
• -> type declares the return type; returning the wrong type is an error.
• Calling with missing or too many arguments is a compile error (E0315 / E0314).
• Arguments can be named and given in any order: greet(greeting: "Hi", name: "Ada").
• Function bodies support var, const, if/elif/else, for ... in, while, return, break, continue, and single-line if cond return x.

Functions can change page state:

function addTodo() {
  if draft.trim() == "" { return }
  todos.push({ text: draft.trim(), done: false })
  draft = ""
}

UI functions

A function returning ui renders markup and can be called inside markup:

function badge(str label, str tone = "info") -> ui {
  Span(class: "badge " + tone) { label }
}

Main {
  badge("New")
  badge("Sale", tone: "danger")
}