How to convert a .ok() match call to a pure match call when returning to a PyResult?

[nth10sd]

use pyo3::exceptions::PyRuntimeError;
use pyo3::prelude::{pyfunction, PyResult};
use std::process::Command;
use which::which;

#[pyfunction]
pub fn list_func(program_name: &str) -> PyResult<bool> {
    match which(program_name).ok() {
        Some(ls_bin) => {
            let output = Command::new(ls_bin).arg("-l").output()?;
            if output.status.success() {
                Ok(true)
            } else {
                Ok(false)
            }
        }
        None => Err(PyRuntimeError::new_err("ls was not found on PATH")),
    }
}

In this example, the which call is fallible because of the .ok() usage. It should work with the ls program to list files, hence ls -l, but if the program is not found, the which call will fail.

May I know how I can drop the usage of the .ok(), making the errors that which returns go to the Err branch instead, whilst continuing to make the result happy with PyResult<bool>? Right now, if the input program does not exist, the code panics.

[birkenfeld]

.ok() does not introduce a panic. It merely converts a Err(e) which carries more information about the error into None, which just carries the information "it didn't work".