How to throw error into Result

I'm still new to Rust. I want to throw an error message into Result<T, E> and it seems to me you can't do that without match. In Javascript you can basically call a callback(error, result) anywhere in the function. What match is doing ? and how to propagate an error with Result<T,E> without match?

I don't like using panic! as it means the program will shuts off immediately when it encounters an error.

Thank you in advance.

use std::io::{Error, ErrorKind}; // im using std::io error here just for example    fn check(array: Vec<usize>) -> Result<bool, Error> {      let a = array.len();      // I need to make it error if the array.len() is 3 or above      match a {          3 => Ok(true),           _ => {              let msg = format!("Invalid array size!");              Err(Error::new(ErrorKind::InvalidData, msg))          }      }  }    fn main(){      let a = vec!(0, 2, 3, 5);      let result = check(a);      let kind = result.map_err(|e| e.kind());      println!("error kind: {:?}", kind);  }  

This doesn't works and prints expected "()", found enum "std::result::Result"

use std::io::{Error, ErrorKind};    fn check(array: Vec<usize>) -> Result<bool, Error> {      // if array.len() is 3 or above it throws an error      if array.len() >= 3 {           let msg = format!("Invalid array size!");          Err(Error::new(ErrorKind::InvalidData, msg))      }      Ok(true)  }    fn main(){      let a = vec!(0, 2, 3, 5);      let result = check(a);      let kind = result.map_err(|e| e.kind());      println!("error kind: {:?}", kind);  }  

PLAYGROUND: https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=bc9c7add4d5081a591413431738a79f5

https://stackoverflow.com/questions/66827800/how-to-throw-error-into-result-t-e-without-match-in-rust March 27, 2021 at 11:41AM