• Ambitious: the aim of being memory safe without the use of a garbage collector, allowing it to achieve C++ execution speeds.

  • Naming conventions:

    • name_with_underscores for variable and function names
    • HttpRequest instead of HTTPRequest for type names
  • Error reporting: compile errors are the best I've seen (though I've only really seen those of C and C++); they are even color-coded!

  • 2 short keywords:

    • fn for function declarations
    • use, instead of using or import
  • I love that I don't need to add (the tedious) parenthesis around the condition expression in an if, while, and match statements:

    if true {
        // always executes
    }
    
    
  • The semicolon rule: I initially found it surprising that omitting a semicolon after a value is shorthand for returning. I appreciate it now... it's quite nifty, and I in fact now find return statements ugly.

  • Traits: they are an elegant way of providing abstract interfaces, and are therefore used in generic programming. As an example, a function can be made to accept different data types, so long as those types implement the given trait (or traits). Gorgeous!

  • The match statement is kool: exhaustiveness check, no fall-through, and nice syntax.

  • Allowing a trailing comma after a list of items, which is really great for copy-pasting and diffs.

  • Packaging conventions: by default, the build tool, Cargo, ensures that all build sources (which may include documentation) are placed in src/ in the root of a source distribution.

  • A fast-paced and time-based release cycle: a stable release will be made every 6 weeks, which is very ambitious for a programming language.

  • Development process:

    • No one, including the Core Team, pushes anything to the Rust tree. Each person gets their changes reviewed first, and they mostly get approved by someone else.
    • Merging the changes to the tree is nearly always done via a continuous integration system, which first ensures that each change passes all tests.
  • Allows masking of variables, even with different types:

    let foo = 10;
    let foo = "ten";
    

    This is convenient.

  • The amount of iterations its design went through during its pre-1.0 development, which included numerous breaking changes, was... impressive. That's an indication that what resulted is a far better design than we could have had. The sheer amount of effort taken, which was such a unique experience for me, makes me feel grateful (I watched the activity for about a year before 1.0 was released). I am also grateful for the resilient users who kept up with the pain of the frequent changes, for they helped keep the language relevant and exciting, while also providing feedback.