Implement REPL resolves #5

src/interpreter.rs

@@ -1,9 +1,9 @@
-use crate::parser::Datum;
-use crate::parser::Datum::*;
-use crate::parser::make_symbol;
 use crate::environment;
 use crate::environment::Env;
- 
+use crate::parser::make_symbol;
+use crate::parser::Datum;
+use crate::parser::Datum::*;
+
 fn is_true(exp: &Datum) -> bool {
     match exp {
         Boolean(b) => *b,
@@ -16,7 +16,7 @@ fn is_true(exp: &Datum) -> bool {
 fn has_tag(vec: &Vec<Datum>, tag: &str) -> bool {
     if vec.len() == 0 {
         return false;
-    } 
+    }
     if let Symbol(s) = &vec[0] {
         if s == tag {
             return true;
@@ -49,7 +49,7 @@ fn interpret_define(args: &Vec<Datum>, env: &mut Env) -> Datum {
             let var = &args[1];
             let val = interpret(&args[2], env);
             environment::define_variable(var, val, env)
-        },
+        }
         List(v) => {
             // procedure definition
             let definition_var = &v[0];
@@ -65,8 +65,8 @@ fn interpret_define(args: &Vec<Datum>, env: &mut Env) -> Datum {
             let lambda_body = Datum::List(args[2..].to_vec());
             let lambda = Datum::List(vec![make_symbol("lambda"), lambda_parameters, lambda_body]);
             environment::define_variable(definition_var, lambda, env)
-        },
-        _ => panic!("INTERPRET-DEFINE -- cannot define {:?}", args)
+        }
+        _ => panic!("INTERPRET-DEFINE -- cannot define {:?}", args),
     }
 }
 
@@ -106,8 +106,8 @@ fn interpret_application(vec: &Vec<Datum>, env: &mut Env) -> Datum {
             }
             environment::shrink_environment(env);
             r
-        },
-        _ => panic!("INTERPRET-APPLICATION -- not-aplicable {:?}", args[0])
+        }
+        _ => panic!("INTERPRET-APPLICATION -- not-aplicable {:?}", args[0]),
     }
 }