use csv::{QuoteStyle, WriterBuilder}; // 1.1.1
use serde; // 1.0.97
use std::io;

#[derive(serde::Serialize)]
struct Dummy {
    abc: String,
    def: f64,
}

fn main() {
    let mut wrt = WriterBuilder::new()
        .quote_style(QuoteStyle::NonNumeric)
        .from_writer(io::stdout());
    wrt.serialize(Dummy {
        abc: "1.01".to_string(),
        def: 1.01,
    }).unwrap();
    wrt.serialize(Dummy {
        abc: "1.01.01".to_string(),
        def: 1.01,
    }).unwrap();
}