Intro to Rust

Where did Rust come from?

In many ways, a reaction to other languages

• Memory safety → borrow checker
• Thread safety → Send and Sync
• Stability without stagnation (or, why unique_ptr has overhead) → source-level backwards compatibility

Memory safety

• Null pointers
• Out-of-bounds accesses
• Use after free (including iterator invalidation)
• Integer overflow

See my previous talk for details

Thread safety

In C especially, most libraries not designed with threads in mind

Example: errno is very broken in the presence of threads (__errno_location)

It turns out all my slides are actually just Amos blog posts repackaged

Backwards compatibility

Or, why is unique_ptr slow?

• C++ has the worst of both worlds: unstable ABI that can't be changedWhat is an ABI?
• Three languages in one
• Python: The standard library is where modules go to die

Reliable

image credit: leftoversalad comics

Type-safety

Option is a library features, not a language feature

Combinators!

let other: Vec<String> = response
  .get("warnings")
  .and_then(|j| j.get("other"))
  .and_then(|j| j.as_array())
  .map(|x| x.iter().flat_map(|j| j.as_str()).map(Into::into).collect())
  .unwrap_or_else(Vec::new);

^ real code taken from cargo

Rust was created by a secret cabal of Haskell developers to teach programmers monads

Type-safety

Result means errors can't be ignored

Let's pick on Go
(taken from official error handling page): playground

f, err := os.Open("filename.ext")
if err != nil {
    log.Fatal(err)
}
// do something with the open *File f

Not unique to Go - C, C++, most HTTP libraries have the same issue

Vaguely adapted from Abstracting Away Correctness

Memory Safe

• "Safe" has a very specific meaning: memory safety and thread safety
• See previous talk for details
• Speed of C/C++ without segfaults
• Borrow checker: shared XOR mutable
• unsafe gives you an escape hatch

The real reason to use rust

The real reason to use rust

Ferris emojis