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