Aura

Docs/Language

Language

Language tour

Map of the language surface — start here, then dive into each topic.

This is the index for the language guides. For normative rules, always prefer RFC-001 and RFC-002.

Hello shape

aura
package main

fun main() {
  println("Hello, Aura")
}

Every file lives in a package. Programs enter at fun main().

Topic guides

GuideWhat you learn
Types & nullabilityScalars, T vs T?, flow narrowing
Classes, structs & interfacesReference vs value types, generics
Control flow & errorsif/for/match, Result, throw/catch
ArraysArray<T>, push/pop, iteration, Int·String HOF
Syntax cheatsheetCompact lookup (lambdas, String, process I/O)
Standard librarystd.io, std.assert, std.collections, prelude

What works in the compiler today

These topics match in-tree behavior (corpus + CLI), not only Accepted RFCs:

  • Packages, functions, locals, expressions
  • Nullability flow, force-unwrap !!, coalesce ?:, safe call ?.
  • Classes (GC), structs (value), interfaces (class C : I), monomorphized generics (incl. generic iface/class implements)
  • Enums + match, Result
  • throw / try / catch / finally; if as expression
  • Array<T> (+ clone, nested free), ranges, for-in (array / string bytes / Iterable)
  • String +, "hi ${name}" interpolation (idents), substring(start, end) (exclusive end; UTF-8 byte indices)
  • Other String helpers: len, isEmpty, charAt, startsWith / contains / endsWith, indexOf, split, trim / trimStart / trimEnd, toInt(): Int?
  • type aliases, top-level const, is type test
  • Expression-body functions fun f(): T = expr
  • First-class functions / lambdas: (x: T) => expr, block body, fun type (T) -> U
  • Captures: outer val of Int / Bool / String / class / Array; outer var of Int / Bool by ref (no nested Fun or var String/class/Array yet)
  • Multi-file packages, imports, path deps; aura new / init / version
  • aura run / test pass-through after --; aura test + @test
  • std.io console + file + argv / stdin / exit / tryReadFile; std.assert
  • std.collections Map/Set/HashMap/HashMapStr/Iterable + Int·String HOF + join
  • Dogfood CLI: examples/wc (args + String tools)

Still design-first (limited or deferred in code)

  • Remaining lambda captures (nested Fun; var String/class/Array) — see repo debts
  • Full task / async surface (RFC-003, RFC-006)
  • Macros / plugins (RFC-010)
  • Reflection (RFC-009)
  • LLVM backend as default (RFC-004 — C backend is what runs now)
  • Registry fetch / semver (RFC-005 — path deps + lock schema only)
  • Generic HashMap<K,V> (concrete String→Int and String→String only)

See the roadmap map for a per-RFC table.

Next

  1. Getting started if you have not run hello yet
  2. Types & nullability
  3. Syntax cheatsheet when you need a quick lookup
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