Here's an example of how you might write a program in Rust to transpile TypeScript code to JavaScript code:

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use std::fs;

fn main() {
    let ts_code = fs::read_to_string("input.ts").expect("Failed to read input file");

    let js_code = transpile_typescript_to_javascript(ts_code);

    fs::write("output.js", js_code).expect("Failed to write output file");
}

fn transpile_typescript_to_javascript(ts_code: String) -> String {
    // TODO: Implement TypeScript to JavaScript transpilation here

    ts_code // Placeholder return value; this will need to be updated with the transpiled code
}

This program reads in a file containing TypeScript code (in this example, the file is called input.ts), transpiles the TypeScript code to JavaScript using the transpile_typescript_to_javascript() function, and then writes the transpiled code to an output file (in this example, the file is called output.js).

The transpile_typescript_to_javascript() function is where you would implement the logic for actually performing the transpilation from TypeScript to JavaScript. This would likely involve using a Rust library for parsing TypeScript code, and then generating the corresponding JavaScript code based on the parsed TypeScript code.

Note that this is just an example of how you might approach this problem, and there are many other ways you could implement a TypeScript to JavaScript transpiler in Rust.