I am under the impression that Rust is lacking even the most basic level of dependent typing: being able to template over a value; pretty much every typesafe buffer library I have ever written uses this to make Random<32>() return not just "a buffer" but "a buffer of size 32", which makes doing parsing of various packet formats and combining sources of information a lot more reasonable. (I am also under the impression that the Rust people intend to fix this lacking, but until then I know I am going to feel a bit crippled.)