[ecshafer]

Swift and Rust were developed at similar times. I think of them more as having similar influences than borrowing from each other.

[pohl]

There’s no reason to invent your own head canon, the influence was openly acknowledged when Swift was new and it continues now that the language is developed out in the open (see Swift Ownership Manifesto)

[zarzavat]

Obviously Rust was first but over time both languages have been taking inspiration from each other. For example let-else was motivated directly because of its success in Swift: https://rust-lang.github.io/rfcs/3137-let-else.html#prior-ar...

[pjmlp]

Additionally both have influences from CLU, C++, Object Pascal, Modula-2, Mesa/Cedar, Standard ML, Cyclone.

Many features that get discussed as being Swift/Rust, trace back to one of those languages.

[est31]

Similar times and the Rust originator went on to work on Swift after it.

[DenisChetwynd]

Graydon Hoare's impact on the language is marginal than that of Chris Lattner, the originator (also, Hoare joined the team much later)