https://smallcultfollowing.com/babysteps/series/cyclic-trait-impls/Recent content in Cyclic Trait Impls on baby stepsHugoen-usrust@nikomatsakis.com (Niko Matsakis)rust@nikomatsakis.com (Niko Matsakis)Mon, 10 Aug 2026 09:35:40 -0400https://smallcultfollowing.com/babysteps/blog/2026/08/10/cyclic-trait-solving/Mon, 10 Aug 2026 09:35:40 -0400rust@nikomatsakis.com (Niko Matsakis)https://smallcultfollowing.com/babysteps/blog/2026/08/10/cyclic-trait-solving/<p>Lately I&rsquo;ve been thinking about cyclic trait implementations. This is a problem that I&rsquo;ve been trying to understand for years and years and I <em>finally</em> feel like I&rsquo;m geting somewhere. I&rsquo;m going to try to write out a series of blog posts documenting those explorations and, hopefully, culminating in a design that could be RFC&rsquo;d. In this first post, I want to talk about one of the interesting questions, what I am going to call &ldquo;internal&rdquo; vs &ldquo;external&rdquo; proofs. I know that this material can seem abstract, so I&rsquo;m going to try and connect it to &ldquo;real Rust&rdquo; as much as possible! This particular blog post is an introduction, explaining the general problem and giving some motivation for why we care.</p>