diff --git a/mist-test/src/logger.mist b/mist-test/src/logger.mist
index 94c4b4a..2b567eb 100644
--- a/mist-test/src/logger.mist
+++ b/mist-test/src/logger.mist
@@ -1,9 +1,29 @@
+use <std::fmt>;
+
 public enum LogLevel {
     Info,
     Warning,
     Error,
 }
 
+impl fmt::Display for LogLevel {
+    std::fmt::Result fmt(self*, std::fmt::Formatter<'_> mut* f) {
+        match (self) {
+            LogLevel::Info => {
+                write!(f, "[INFO]");
+            }
+
+            LogLevel::Warning => {
+                write!(f, "[WARN]");
+            }
+
+            LogLevel::Error => {
+                write!(f, "[ERROR]");
+            }
+        }
+    }
+}
+
 public class Logger {
     String prefix;
 
diff --git a/parser/src/grammar.pest b/parser/src/grammar.pest
index 7d99a5d..afc0ea4 100644
--- a/parser/src/grammar.pest
+++ b/parser/src/grammar.pest
@@ -239,8 +239,24 @@ method = {
     export? ~ type_expr ~ identifier ~ generics? ~ "(" ~ self_param? ~ ("," ~ param_list?)? ~ ")" ~ block
 }
 
+class_item = _{
+    impl_decl
+  | method
+}
+
 class_decl = {
-    export? ~ "class" ~ identifier ~ generics? ~ "{" ~ class_fields ~ class_constructor ~ method* ~ "}"
+    export? ~ "class" ~ identifier ~ generics? ~ "{" ~ class_fields ~ class_constructor ~ class_item* ~ "}"
+}
+
+// ======================================================
+// IMPL
+// ======================================================
+impl_for_decl = {
+    "impl" ~ generics? ~ type_expr ~ "for" ~ type_expr ~ "{" ~ method* ~ "}"
+}
+
+impl_decl = {
+    "impl" ~ generics? ~ type_expr ~ "{" ~ method* ~ "}"
 }
 
 // ======================================================
@@ -256,7 +272,7 @@ function_decl = {
 // ======================================================
 
 top_level = {
-    (attributes ~ (import | function_decl | struct_decl | enum_decl | class_decl | mod_package))
+    (attributes ~ (import | impl_for_decl | impl_decl | function_decl | struct_decl | enum_decl | class_decl | mod_package))
   | mod_attribute
 }