wordcount.rs in Rust

A complete word-frequency program: read stdin, tally, sort, print.

use std::collections::HashMap;
use std::io::{self, Read};

fn main() {
    let mut input = String::new();
    io::stdin()
        .read_to_string(&mut input)
        .expect("failed to read stdin");

    let mut counts: HashMap<String, usize> = HashMap::new();
    for raw in input.split_whitespace() {
        let word: String = raw
            .trim_matches(|c: char| c.is_ascii_punctuation())
            .to_lowercase();
        if !word.is_empty() {
            *counts.entry(word).or_insert(0) += 1;
        }
    }

    let mut pairs: Vec<_> = counts.into_iter().collect();
    pairs.sort_by(|a, b| b.1.cmp(&a.1));
    for (word, count) in pairs.into_iter().take(10) {
        println!("{count:6}  {word}");
    }
}

Keywords and builtins used here

• HashMap
• String
• Vec
• char
• fn
• for
• if
• in
• let
• main
• mut
• self
• use
• usize

The run, in numbers

Lines

25

Characters to type

602

Tokens

198

Three-star pace

110 tpm

At the three-star pace of 110 tokens a minute, this run takes about 108 seconds.

Type this snippet

Step 1 of 1 in Encore, step 14 of 14 in Iterators & closures.

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