语言设计： Rust 的几乎规则

(灵感来自 Almost Rules.)

语法

: 后跟一个类型

• except inside struct initializers, where it is followed by a value
• except function result types, which are preceded by ->

泛型使用 <>

• except in expression contexts, which uses ::<>

调用使用 ()

• except where {} or [] is used, because “they convey important information”
  • except for macro invocations, where (), {}, [] are equivalent and interchangeable

T {} 初始化结构体

• except inside an if, where { starts a branch

Rust 没有 varargs

• except for extern functions
• except for macros

let 引入绑定

• except in pattern matching, where let is implied
  • except if there is a identifier with that name in scope, then it refers to it
    • except if the identifier is only a let, not a const
  • except in macro pattern matching, where identifiers are matched verbatim

语义

有总序的类型实现 Eq 和 Ord

• except f64 and f32, which do not

结构体初始化器使用临时生命周期扩展

• except tuple structs
  • except when using curly braces to initialize tuple structs