Switch to using tracing instead of logging.

Cargo.toml

@@ -11,8 +11,8 @@ path = "src/main.rs"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-log = "0.4.17"
 nom = "7.1.1"
-pretty_env_logger = "0.4.0"
+tracing = "0.1.37"
+tracing-subscriber = "0.3.16"
 
 [features]

src/main.rs

@@ -5,7 +5,8 @@ mod parser;
 const TEST_DOC: &'static str = include_str!("../toy_language.txt");
 
 fn main() -> Result<(), Box<dyn std::error::Error>> {
-    pretty_env_logger::init();
+    let subscriber = tracing_subscriber::FmtSubscriber::new();
+    tracing::subscriber::set_global_default(subscriber)?;
     println!("{}\n\n\n", TEST_DOC);
     println!("{:#?}", document(TEST_DOC));
     Ok(())