Covariant and Contravariant Lifetimes
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What is Covariant and Contravariant Lifetimes?
Variance describes how subtyping relationships change when types are nested. Covariant types preserve ordering (&'long T is subtype of &'short T), contravariant reverses it, invariant requires exact matches. Affects how lifetimes work with references, boxes, and function parameters.
Free resources to learn Covariant and Contravariant Lifetimes
- Official docsSubtyping and Variance
- ArticleDemystifying Covariant and Contravariant Lifetimes in Rust
More in stage 10: Web Development
Covariant and Contravariant Lifetimes: common questions
Can I learn Covariant and Contravariant Lifetimes in Hindi?
This lesson is written in English. Once you sign in, open it in the interactive course and ask the AI tutor to explain Covariant and Contravariant Lifetimes in Hindi or Hinglish. The tutor answers from this lesson’s own text, so it stays on the syllabus, and it runs on your own Google, OpenAI or Anthropic key.
Is this Covariant and Contravariant Lifetimes tutorial for beginners?
It is lesson 73 of 122 in the free Rust roadmap, in stage 10, Web Development. If you are new to Rust, start from stage 1 and come back here in order; if you already know the earlier stages, this lesson stands on its own.