Initial data commit

Task/CSV-data-manipulation/Rust/csv-data-manipulation.rust

@@ -0,0 +1,28 @@
+use std::error::Error;
+use std::num::ParseIntError;
+use csv::{Reader, Writer};
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let mut reader = Reader::from_path("data.csv")?;
+    let mut writer = Writer::from_path("output.csv")?;
+
+    // headers() returns an immutable reference, so clone() before appending
+    let mut headers = reader.headers()?.clone();
+    headers.push_field("SUM");
+    writer.write_record(headers.iter())?;
+
+    for row in reader.records() {
+        let mut row = row?;
+
+        // `sum` needs the type annotation so that `parse::<i64>` knows what error type to return
+        let sum: Result<_, ParseIntError> = row.iter().try_fold(0, |accum, s| {
+            Ok(accum + s.parse::<i64>()?)
+        });
+
+        row.push_field(&sum?.to_string());
+        writer.write_record(row.iter())?;
+    }
+
+    writer.flush()?;
+    Ok(())
+}