И три точки в rust'е есть... Но они не используются для slice'ов. И можно только в for'е или в match'е писать
Note that slicing is "exclusive" (so [n..m] is the interval n <= x < m), while .. in match patterns is "inclusive". To avoid confusion, we propose to change the match notation to ... to reflect the distinction. The reason to change the notation, rather than the interpretation, is that the exclusive (respectively inclusive) interpretation is the right default for slicing (respectively matching).
Some other languages (like Python and Go -- and Fortran) use : rather than .. in slice notation. The choice of .. here is influenced by its use elsewhere in Rust, for example for fixed-length array types [T, ..n]. The .. for slicing has precedent in Perl and D.