Rust

Goal

Write a Rust block that works without any crates. Time: 10 minutes. Needs: rustc with edition 2024 support.

language: rust
outputs:
  type: object
  properties:
    input_bytes:
      type: number

use std::{env, error::Error, fs};

fn main() -> Result<(), Box<dyn Error>> {
    let path = env::var("TERMORQ_INPUT")?;
    let input = fs::read(path)?;
    println!("{{\"input_bytes\":{}}}", input.len());
    Ok(())
}

Things to know

The runner compiles with rustc --edition 2024 -O, then runs the binary. There’s no Cargo, so crates such as serde_json aren’t available.
The standard library has no JSON parser. Use Rust for byte, line, or number processing, and use another language for JSON field transformations.
Use format! and println! for output. Escape { and } by doubling them. Only interpolate values that can’t contain quotes, backslashes, or newlines, or escape them yourself.
Returning Err from main exits with a non-zero code, so the block fails.

Check your run

With the exact compact sample {"trigger":{"text":"Hello from curl"}} (no trailing newline), the output is {"input_bytes":38}. That’s the UTF-8 byte count of the whole file.

Exercise

Publish lines (number): the number of lines in the input file. Test it with multi-line plain text in Step input.

Details

use std::{env, fs};
fn main() {
    let text = fs::read_to_string(env::var("TERMORQ_INPUT").unwrap()).unwrap();
    println!("{{\"lines\":{}}}", text.lines().count());
}