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// Copyright 2014 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your // option. This file may not be copied, modified, or distributed // except according to those terms. #![doc(primitive = "unit")] #![stable(feature = "rust1", since = "1.0.0")] //! The `()` type, sometimes called "unit" or "nil". //! //! The `()` type has exactly one value `()`, and is used when there //! is no other meaningful value that could be returned. `()` is most //! commonly seen implicitly: functions without a `-> ...` implicitly //! have return type `()`, that is, these are equivalent: //! //! ```rust //! fn long() -> () {} //! //! fn short() {} //! ``` //! //! The semicolon `;` can be used to discard the result of an //! expression at the end of a block, making the expression (and thus //! the block) evaluate to `()`. For example, //! //! ```rust //! fn returns_i64() -> i64 { //! 1i64 //! } //! fn returns_unit() { //! 1i64; //! } //! //! let is_i64 = { //! returns_i64() //! }; //! let is_unit = { //! returns_i64(); //! }; //! ```