Fibonacci

rust_vs_crystal

# Crystal cfib.cr
def fib(n)
  if n <= 2
    1
  else
    fib(n - 1) + fib(n - 2)
  end
end
puts fib(42)
$ crystal build cfib.cr --release
$ strip cfib
# cfib size is 306480 byte

# Rust rfib.cr
pub fn fib(n: i32) -> u64 {
    if n <= 2 {
        1
    } else {
        fib(n - 1) + fib(n - 2)
    }
}
fn main() {
    println!("{}", fib(42));
}
$ rustc -C opt-level=3 rfib.rs
$ strip rfib
# rfib size is 194920 byte

$ time ./cfib 
267914296

real	0m0.696s
user	0m0.691s
sys	0m0.004s

$ time ./rfib 
267914296

real	0m0.646s
user	0m0.642s
sys	0m0.004s
# <-- This is 42 line