Try to make the store representation smaller

Cargo.toml

@@ -10,3 +10,4 @@ csv = "1.1.6"
 serde = { version = "1.0.145", features = ["derive"] }
 serde_repr = "0.1.9"
 extindex = "0.5.0"
+rust_decimal = "1.26.1"

src/main.rs

@@ -1,9 +1,11 @@
 use csv::ReaderBuilder;
 use extindex::{Builder, Entry, SerdeWrapper, Reader as ExtReader};
+use rust_decimal::Decimal;
 use std::error::Error;
 use std::io;
 use std::path::Path;
 use std::process;
+use std::str::FromStr;
 use serde::{Deserialize, Serialize};
 use serde;
 use serde_repr::*;
@@ -74,20 +76,24 @@ struct SmolPostcode {
     usertype: UserType,
     positional_quality_indicator: PositionalQuality,
     country: String,
-    latitude: Option<String>,
-    longitude: Option<String>,
+    latitude: Option<Decimal>,
+    longitude: Option<Decimal>,
 }
 
 impl SmolPostcode {
     fn from_postcode(full: Postcode) -> Self {
+        let to_dec = |n: Option<String>| match n {
+            Some(str) => Decimal::from_str(&str).ok(),
+            None => None,
+        };
         SmolPostcode {
             postcode: full.postcode.to_owned(),
             status: full.status,
             usertype: full.usertype,
             positional_quality_indicator: full.positional_quality_indicator.to_owned(),
             country: full.country.to_owned(),
-            latitude: full.latitude.to_owned(),
-            longitude: full.longitude.to_owned(),
+            latitude: to_dec(full.latitude),
+            longitude: to_dec(full.longitude),
         }
     }
 }
@@ -99,8 +105,10 @@ fn read() -> Result<(), Box<dyn Error>> {
     let mut i: u32 = 0;
     for result in rdr.deserialize() {
         let record: Postcode = result?;
-        // println!("{}:: {:?}", i, record);
+        println!("{}:: {:?}", i, &record);
         i += 1;
+        let smol = SmolPostcode::from_postcode(record);
+        println!("As smol: {:?}", smol);
     }
     println!("Read {:?} postcodes", i);
     Ok(())
@@ -127,10 +135,6 @@ fn csv_iter(file: impl io::Read + 'static) -> impl Iterator<Item=String> {
 
 fn main() {
     build();
-    if let Err(err) = read() {
-        println!("error running example: {}", err);
-        process::exit(1);
-    }
 }