Philippe Gaultier • 3/6/2026

In Rust, <code>let _ = ...</code> and <code>let _unused = ...</code> are not the same

This technical article clarifies a key distinction in Rust: using `let _ = ...` versus `let _unused = ...` to handle unused values. It demonstrates through a concrete example of implementing a live-reload server with threads and condition variables, explaining why `let _` can be problematic for locks and how the compiler's `let_underscore_lock` lint enforces correct patterns.

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#concurrency #rust #Pattern Matching