all tests pass

examples/scopes.rs

+fn main() {
+    let mut a = 7;
+    let mut b;
+    {
+        a = 5;
+        b = false;
+        let mut a = false;
+        a = true;
+    };
+    a = 0;
+    b = true;
+}

examples/scopes_err.rs

+fn main() {
+    let mut a = 7;
+    let mut b;
+    {
+        a = 5;
+        b = false;
+        let mut a = false;
+        a = true;
+    };
+    a = false;
+    b = true;
+}

src/vm.rs

@@ -286,7 +286,7 @@ fn eval_stmts(stmts: &Stmts, m: &mut Mem, fn_env: &FnEnv) -> Val {
                 println!("block");
                 eval_stmts(block, m, fn_env)
             }
-            Stmt::Semi => panic!("ICE"),
+            Stmt::Semi => Val::Unit,
         }
     }
     m.pop_scope();

tests/test_parser.rs

@@ -56,36 +56,37 @@ fn test_exprs() {
 #[test]
 fn test_stmts() {
     // test empty sequence
-    assert!(BlockParser::new().parse("").is_ok());
+    assert!(BlockParser::new().parse("{}").is_ok());
 
     // test let with no assignment and inferred type
-    assert!(BlockParser::new().parse("let a").is_ok());
+    assert!(BlockParser::new().parse("{ let a }").is_ok());
 
     // test let with no assignment and excplicit type
-    assert!(BlockParser::new().parse("let a : u32").is_ok());
+    assert!(BlockParser::new().parse("{ let a : u32 }").is_ok());
 
     // test let with inferred type
-    assert!(BlockParser::new().parse("let a = 0").is_ok());
+    assert!(BlockParser::new().parse("{ let a = 0 }").is_ok());
 
     // test let with explicit type
-    assert!(BlockParser::new().parse("let a : u16 = 1 + 2").is_ok());
+    assert!(BlockParser::new().parse("{ let a : u16 = 1 + 2 }").is_ok());
 
     // test assignment
-    assert!(BlockParser::new().parse("a = 1 + 2").is_ok());
+    assert!(BlockParser::new().parse("{ a = 1 + 2 }").is_ok());
 
     // test assignment
-    assert!(BlockParser::new().parse("*a = 1 + 2").is_ok());
+    assert!(BlockParser::new().parse("{ *a = 1 + 2}").is_ok());
 
     // test if then
-    assert!(BlockParser::new().parse("if a { b = 5 }").is_ok());
+    assert!(BlockParser::new().parse("{ if a { b = 5 } }").is_ok());
 
     // test if then else
     assert!(BlockParser::new()
-        .parse("if a { b = 5 } else { b = 7 }")
+        .parse("{ if a { b = 5 } else { b = 7 } }")
         .is_ok());
 
+    // test hello
     assert!(BlockParser::new()
-        .parse("while hello(b) { b = b - 5 }")
+        .parse("{ while hello(b) { b = b - 5 } }")
         .is_ok());
 }
 

tests/test_vm.rs

@@ -55,13 +55,13 @@ fn while_test() {
 }
 
 #[test]
-fn mut_test() {
-    eval_prog("examples/mut.rs");
+fn let_test() {
+    eval_prog("examples/let.rs");
 }
 
 #[test]
-fn mut2_test() {
-    eval_prog("examples/mut2.rs");
+fn let2_test() {
+    eval_prog("examples/let2.rs");
 }
 
 #[test]