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The primitive integer types supported by CPUs are finite approximations to the infinite set of integers we’re all used to. This approximation breaks down and some computations will give results that don’t match real integers, like 255_u8 + 1 == 0. Often, this mismatch is something the programmer didn’t think about, and thus can easily result in bugs. Rust is a programming language designed to prot

Imagine being able to step forward and backwards as code runs in your debugger. Imagine being able to do an test run multiple times with exactly the same sequence of instructions and values, right down to memory addresses and IO. Imagine being able to run an executable thousands of times and then do all that in the one execution that triggers the rare bug that’s draining you of life… The rr tool i

A new scheme for SIMD in Rust is available in the latest nightly compilers, fresh off the builders (get it while it’s hot!). For the last two months, I’ve been interning at Mozilla Research, working on improving the state of SIMD parallelism in Rust: exposing more CPU instructions in the compiler, and an in-progress library that provides a mostly-safe but low-level interface to that core functiona

Have you ever used an iterator adapter in Rust? Called a method on Option? Spawned a thread? You’ve almost certainly used a closure. The design in Rust may seem a little complicated, but it slides right into Rust’s normal ownership model so let’s reinvent it from scratch. The new design was introduced in RFC 114, moving Rust to a model for closures similar to C++11’s. The design builds on Rust’s s

Rust is a reasonably large project: the compiler and standard libraries are over 350kloc, built across nearly 40000 commits by the hands of around 900 contributors. Not only that: there are more than 30 other repositories in the rust-lang GitHub organisation that shouldn’t fall by the wayside, and, for rust-lang/rust alone, there are often more than 100 pull requests landing and a dozen new contri

A trait object in Rust0 can only be constructed out of traits that satisfy certain restrictions, which are collectively called “object safety”. This object safety can appear to be a needless restriction at first, I’ll try to give a deeper understanding into why it exists and related compiler behaviour. This is the second (and a half) in a short series of articles on trait objects. The first one—Pe

An important piece in my story about trait objects in Rust0 is the Sized trait, so I’m slotting in this short post between my discussion of low-level details and the post on “object safety”. Other posts in this series on trait objects Peeking inside Trait Objects The Sized Trait Object Safety Where Self Meets Sized: Revisting Object Safety Sized is a (very) special compiler built-in trait that is

One of the most powerful parts of the Rust programming language0 is the trait system. They form the basis of the generic system and polymorphic functions and types. There’s an interesting use of traits, as so-called “trait objects”, that allows for dynamic polymorphism and heterogeneous uses of types, which I’m going to look at in more detail over a short series of posts. Update 2015-02-19: A lot