Initializes an array with constant values calculated by a
const fn (usize) -> usize
Requires Rust >= 1.45
```rust use arrayconstfninit::arrayconstfninit;
const fn constdoubleit(i: usize) -> usize { i * 2 } const ARRAY: [usize; 10] = arrayconstfninit![constdoubleit; 10]; asserteq!(ARRAY, [0, 2, 4, 6, 8, 10, 12, 14, 16, 18]); ```