[Georgelemental]

Rust takes the "at least annotate all your function signatures" approach as well. It's essential for making borrow-checking tractable (for both the compiler and the programmer).

[ReleaseCandidat]

Rust has the "you must annotate your functions signatures, because there is no global type inference possible" approach.

[Mawr]

It's a carefully chosen, deliberate design decision [1]. Interface boundaries should be stable.

[1] https://steveklabnik.com/writing/rusts-golden-rule