concatenate strings differently

build.rs

@@ -1,6 +1,7 @@
 use std::env;
 use std::fs;
 use std::path::Path;
+use std::iter::once;
 
 fn main() {
 	let out_dir = env::var_os("OUT_DIR").unwrap();
@@ -41,7 +42,11 @@ fn main() {
 
 	fs::write(
 		&dest_path,
-		"vec![".to_string() + &lines.iter().map(|x|x.as_str()).collect::<String>() + "]"
+		once("vec![")
+			.chain(lines.iter()
+				   .map(String::as_str)
+				   .chain(once("]")))
+			.collect::<String>()
 	).unwrap();
 
 	println!("cargo::rerun-if-changed=build.rs");