How to init a Rust vector with a generator function?

Pretty late to this party, but: resize_with

You can use a range withing a map and then collect the results.

Like in the example for F# docs:

let my_vector : Vec<i32> = (1..11).map(|x| x*x).collect();

Check this Playground

Though @Netwave provides the answer, I'd point to a solution which uses it and provides both more reusability and readability.

1. Define a generic function, playground:

   fn initialize<T>(count: usize, f: fn(usize) -> T) -> Vec<T> {
       (0..count).map(f).collect()
   }
   
   fn main() {
       let my_vector = initialize(10, |i| i as i32);
       for e in my_vector {
            println!("{}", e);
       }
   }
   

2. Define a trait, implement it for whatever you want and use it, playground:

   trait Initializer<T> {
       fn initialize(count: usize, f: fn(usize) -> T) -> Vec<T> {
           (0..count).map(f).collect()
       }
   }
   
   impl<T> Initializer<T> for Vec<T> {}
   
   fn main() {
       let my_vector = Vec::initialize(10, |i| i as i32);
       for e in my_vector {
           println!("{}", e);
       }
   }
   

   or more general way:

   trait Initializer<T, U> {
       fn initialize(count: usize, f: fn(usize) -> U) -> T;
   }
   
   impl<T: std::iter::FromIterator<U>, U> Initializer<T, U> for T {
       fn initialize(count: usize, f: fn(usize) -> U) -> T {
           (0..count).map(f).collect::<T>()
       }
   }
   
   fn main() {
       let my_vector = Vec::initialize(10, |i| i as i32);
       for e in my_vector {
           println!("{}", e);
       }
   }
   

3. Write a macro, playground:

   macro_rules! vec_init {
       ($count: expr, $f: expr) => { (0..$count).map($f).collect() }
   }
   
   fn main() {
       let my_vector: Vec<i32> = vec_init!(10, |i| i as i32);
   }
   

The base still the same is in the @Netwave's answer. You've asked that you want something like:

// Looking for something similar to:
Vec<T>::init(n : usize, generator : F) -> Vec<T> 
    where F: Fn(usize) -> T {
    // ...
}

And there is exactly this code in the second item.