Implement basic lexer

src/main.rs

@@ -1,6 +1,9 @@
 mod lexer;
+mod parser;
 
 fn main() {
-    let scm_code = "(+ a 32)";
-    lexer::read(scm_code);
+    let scm_code = "(+ a (* 32 b) c #t #f)";
+    let tokens = lexer::read(scm_code);
+    let datum = parser::parse(tokens);
+    println!("{:?}", datum);
 }