feat: add repl bin

src/repl.rs

@@ -0,0 +1,33 @@
+use lisp::Expression;
+use parser::ParserError;
+
+use std::io::Write;
+mod parser;
+mod lisp;
+
+fn main() {
+    let env = lisp::Environment::default();
+
+    loop {
+        print!("> ");
+        std::io::stdout().flush().unwrap();
+
+        let mut input = String::new();
+        if std::io::stdin().read_line(&mut input).unwrap() == 0 {
+            println!("Exiting REPL...");
+            break;
+        }
+
+        match parser::ExpressionStream::from_char_stream(input.chars()).collect::<Result<Vec<Expression>, ParserError>>() {
+            Err(e) => println!("Parser Error: {:?}", e),
+            Ok(exprs) => {
+                for expr in exprs {
+                    match lisp::eval(&env, expr) {
+                        Err(e) => println!("Eval Error: {}", e),
+                        Ok(val) => println!("{}", val),
+                    }
+                }
+            }
+        }
+    }
+}