One of the nice things about Dart in particular is that they are actually very aware that they are currently a small community.
In that sense they ended up making a big focus on having great interop with other languages. Currently they have C, C++, Rust, Swift, JavaScript (browser and node), Java, Kotlin and Objective C all more or less working and an upcoming goal of WASI will also open up that entire ecosystem.
Plus all of your usual interop solutions for out of process communication. I.e anything that speaks gRPC like Ruby, C#, Go, PHP etc has strongly typed automatically generated code libraries for you.
In that sense they ended up making a big focus on having great interop with other languages. Currently they have C, C++, Rust, Swift, JavaScript (browser and node), Java, Kotlin and Objective C all more or less working and an upcoming goal of WASI will also open up that entire ecosystem.
Plus all of your usual interop solutions for out of process communication. I.e anything that speaks gRPC like Ruby, C#, Go, PHP etc has strongly typed automatically generated code libraries for you.