Gossamer language reference

One page per language feature. Source is crates/gossamer-std/src/manifest/feature_status.rs; this index is regenerated from manifest::FEATURE_STATUS by gos doc --emit-stdlib.

Feature	Status	Summary
lang::let	shipped	Immutable binding.
lang::let_mut	shipped	Mutable binding.
lang::if	shipped	Conditional expression.
lang::match	shipped	Exhaustive pattern match expression.
lang::if_let	shipped	Single-variant pattern sugar.
lang::while_let	shipped	Loop that drains while a pattern matches.
lang::for	shipped	Iterator-driven loop.
lang::loop	shipped	Unconditional loop with break value.
lang::break	shipped	Exit the innermost loop, optionally with a value.
lang::continue	shipped	Skip to the next iteration of the innermost loop.
lang::return	shipped	Exit the enclosing function with a value.
lang::question_mark	shipped	Short-circuit Result / Option propagation operator.
lang::pipe	shipped	Forward-pipe operator \|>.
lang::closure	shipped	Lambda expression \|args\| body.
lang::fn	shipped	Function declaration.
lang::struct	shipped	Product type declaration.
lang::enum	shipped	Sum type declaration with payload-carrying variants.
lang::trait	shipped	Behaviour interface declaration.
lang::impl	shipped	Inherent and trait implementation blocks.
lang::generics	shipped	Type parameters on functions / impls / structs.
lang::go	shipped	Goroutine spawn.
lang::select	shipped	Channel multiplex select expression.
lang::channel	shipped	Typed channel via std::sync::channel.
lang::spawn	shipped	Goroutine join handle: spawn(f) -> JoinHandle<T>, .join() -> Result<T, String>.
lang::macros	shipped	Six built-in format macros (print/println/eprint/eprintln/format/panic).
lang::doctest	shipped	Fenced code in // doc comments runs under gos test.
lang::cfg	shipped	Conditional compilation attribute.
lang::attribute	shipped	Built-in attributes (#[cfg], #[test], #[bench], #[derive]).
lang::const	shipped	Compile-time constant binding.
lang::static	shipped	Module-level mutable or immutable static slot.
lang::mut_ref_params	shipped	&mut Vec<T> / &mut [T] parameters write through to the caller's storage on every tier.
lang::unicode_identifiers	shipped	Identifiers follow UAX #31 (matches Rust 2024).
lang::move_keyword	planned	move closure capture keyword - parses, lowers to the same Fn shape as a non-move closure (the runtime manages ownership).
lang::async_await	planned	async fn / .await - goroutines + channels cover the same shape today.
lang::lifetimes	planned	Explicit lifetime annotations - not needed under the current memory model; tracked in case a borrow-checker mode lands.