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Rust is famous for its ownership type-system, but requires the programmer to annotate ownership in function signatures. Is it possible to do full program inference of ownership, without any annotations? What would be the pros and cons of such a system?

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    $\begingroup$ The term you might be looking for is partial type inference. The reason why many languages don't have full type inference is that once you go beyond Hindley/Milner let-polymorphism, full type inference is generally undecidable. $\endgroup$ Jun 29 '20 at 16:41
  • $\begingroup$ @MartinBerger No. Rust already has partial inference. This question is about full inference. $\endgroup$ Jun 29 '20 at 18:24
  • $\begingroup$ I know that Rust has partial type inference. I was just clarifying terminology. $\endgroup$ Jun 29 '20 at 19:19
  • $\begingroup$ As a general rule of thumb, any dynamic feature of a langauge (ownership at runtime, effects, shape of heap, what is printed out) can only be approximated by a type system that has algorithmic checking or inference, because questions about the dynamic behavior of programs get undecidable really fast. One always ends up balancing expressivity and simplicity. $\endgroup$ Jul 1 '20 at 8:51
  • $\begingroup$ @OlleHärstedt what Andrej said is formalised in the famous Rice's Theorem. $\endgroup$ Jul 4 '20 at 11:08

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