| The default types for bare literals is described in RFC #212 (https://github.com/rust-lang/rfcs/pull/212) To summarize: bare FP literals default to f64, bare integral literals default to isize. (NOTE: isize is recently renamed from int. It is a pointer-sized integer.) (EDIT: The default for integer literals may be superseded by a later RFC. I seem to recall that the default is actually i32 now, but I can't find a PR to back up that claim.) So you could easily get a Vec3<f64> like so: let mut s = Vec3 { x: 0.0, y: 0.0, z: 0.0, w: 0.0 };
let mut t = Vec3 { x: 0f64, y: 0.0, z: 0.0, w: 0.0 };
The key here is that integral literals and floating point literals are distinct.A bare literal of the form `0` is an unconstrained integral literal. Whereas a literal of the form `0.0` or `.0` is an unconstrained float literal. In practice it is very rare for me to annotate my numeric literals. If the variable escapes the stack frame it will be constrained by the signature of the function anyways. If not I constrain the type inline (`let x: T = ...`) and use the appropriate bare literals. |