Documents as Data.
One Language. One Pipeline.

// First-class markup syntax
let card = <div class: "card"
    <h2 "Hello World">
    <p "Lambda treats documents as data.">
>

// Render to HTML string
format(card, 'html')

// Parse any format into a unified tree
let doc = input("readme.md", 'markdown')
let data = input("config.yaml", 'yaml')

// Query the tree
doc?<img>                           // all images in document
doc?<a href: string>                 // all links with href

// Type annotations
let x: int = 42
let items: [string] = ["a", "b"]

// Union and optional types
type Result = int | error
type Name = string?

// Object types with methods
type Point {
    x: float, y: float;
    fn distance(other: Point) =>
        math.sqrt((x - other.x)**2 + (y - other.y)**2)
}

// Element type patterns for document schemas
type Link = <a href: string; string>
type Article = <article title: string; string, Section*>

// Filter and transform with for-expressions
for (x in data where x > 0) x * 2

// With local bindings
for (x in data, let sq = x * x where sq > 10) sq

// Sorting and pagination
for (x in items order by x.price desc limit 5) x.name

// Grouping and aggregation
for (u in users where u.active
     order by u.age desc
     limit 10 offset 5)
  {name: u.name, age: u.age}

fn describe(x) => match x {
    case null:             "nothing"
    case 0:                "zero"
    case 1 to 9:           "small number"
    case int that (~ > 9): "big number"
    case string:           "text: " ++ ~
    case [int]:            "int array"
    default:               "something else"
}

// Query operator — like jQuery for data trees
html?<img>                    // all images
html?<div class: string>      // divs with class
data?{status: "ok"}           // maps with status=="ok"