See Tips for golfing in Rust on CGSE.

Program structure examples

Print all the args:

fn main(){for v in std::env::args().skip(1){print!("{v}
")}}

Print a bunch of numbers:

fn main(){for i in 1..101{if i%9>6{print!("{}
",i*i*i)}}}

Parse input:

// Ordinal Numbers
fn main(){for a in std::env::args(){for n in a.parse::<usize>(){ /* code */ }}}

// Fractions
fn main(){for a in std::env::args(){if let[x,y]=a.split("/").flat_map(str::parse).collect::<Vec<u32>>()[..]{ /* code */ }}}

By using for or if let we avoid the need for both .unwrap() and args().skip(1).

Stateful iteration:

fn main(){let mut k=1;for i in 0..10{print!("{k}␊");k*=3}}
fn main(){(0..10).fold(1,|k,_|{print!("{k}␊");k*3});}
fn main(){f(1)}fn f(k:i16){print!("{k}␊");f(k*3)}          // uses i16 overflow to terminate!

Random tips

• Use @ to assign multiple variables to the same value. For example let a@mut b=12 or for a@mut b in 0..=12 {} or let [a,..@b]=[1;99].
• [b,a][i%5/4] instead of if i%5==4 then{a}else{b} (for example)
• print! with newline in the format string instead of println!
  • However println!() is shorter than print!("␊")
• str.repeat(1) instead of str.to_owned()
• format!("literal") instead of String::new
• Use byte array literals b"asdf"
• Option as iterable (for example use flat_map instead of filter_map, or for s in o instead of if let Some(s)=o)
• Format specifiers are really powerful. For example print!("{:¬^7.3}","abcdefghijkl") prints ¬¬abc¬¬.
  • I've found {:.1} useful to print a single character from a string at an index:

    fn main(){let n=3;println!("{}",&"abcde"[n..=n])}
    fn main(){println!("{}",&"abcde"[3..][..1])}
    fn main(){println!("{:.1}",&"abcde"[3..])}
    

• Remember to use cool methods on ranges like if(1..=n).all(|x|condition)
• Don't forget x.min(y) and x.max(y) (works on ints, strings, Options…)
• .zip(0..) instead of .enumerate()
• Digit sum: n.to_string().chars().fold(0,|a,c|a+c as i32-48)
• It's often better to think of Rust golf as functional golf (.fold is really darn good).
• x as i32 as usize etc can eat a lot of bytes, so try to use one numeric type for everything?
• If you need to iterate 10, 100, or a 1000 times but don't care about the iterator variable, for _ in-1..99 is shorter than for _ in 0..100{}
• use std::println as p; is useful in Cubes :)