Grammar

The grammar source of truth is docs/grammar.ebnf. This page summarizes the current language surface; it is not a generated parser listing.

Source Files

Vela source files use .vela. A source file may contain imports, attributes, constants, VM/extern state declarations, functions, structs, enums, traits, and impl blocks.

use game::reward as reward

#[event("monster.kill")]
fn on_kill(ctx: Context, player: Player) {
    reward::grant(ctx, player, 10);
}

Expressions And Statements

The expression grammar covers literals, arrays, maps, typed record literals, field access, indexing, calls, postfix call .await, unary and binary operators, ranges, lambdas, if, match, and blocks. Module functions and script methods may be declared with async fn.

Assignments require assignable targets: identifiers, fields, indexes, or host path proxies. Compound assignment uses the same write boundary as ordinary assignment.

Patterns

Patterns are used by match and for bindings. The grammar supports wildcard, literal, binding, path, tuple-variant, and record-variant patterns.

Deliberate Exclusions

The grammar intentionally excludes script-language generics, script-visible task or coroutine handles, manual resume, macro expansion, eval, classes, monkey patching, and Rust-style borrow syntax. Async execution remains sequential: .await suspends an async fn until its call completes without exposing script-level concurrency.

Type hints are metadata contracts and analysis inputs. They do not create generic types or monomorphized script functions. Only selected builtin contracts accept type arguments: Array<T>, Set<T>, Map<K, V>, Iterator<T>, Option<T>, and Result<T, E>. Map<K, V> keys and Set<T> elements must satisfy the runtime ValueKey keyability policy. User-defined script generics and non-keyable container contracts are rejected.