diff --git a/include/frontend/checker/common_types.h b/include/frontend/checker/common_types.h
new file mode 100644
index 0000000..a71fc9f
--- /dev/null
+++ b/include/frontend/checker/common_types.h
@@ -0,0 +1,12 @@
+#ifndef COMMON_TYPES_H
+#define COMMON_TYPES_H
+#include <string.h>
+
+#define ISTYPE(typedf, tname) (strcmp(typedf->name, tname) == 0)
+
+#define ISINT(typedf) ISTYPE(typedf, "int")
+#define ISFLOAT(typedf) ISTYPE(typedf, "decimal")
+#define ISSTRING(typedf) ISTYPE(typedf, "string")
+
+
+#endif //COMMON_TYPES_H
diff --git a/include/frontend/checker/core.h b/include/frontend/checker/core.h
index 69e64dc..503f5be 100644
--- a/include/frontend/checker/core.h
+++ b/include/frontend/checker/core.h
@@ -1,17 +1,17 @@
 #ifndef CHECKER_CORE_H
 #define CHECKER_CORE_H
 #include <map>
-#include "../ast/definitions.h"
+#include "frontend/ast/definitions.h"
 
-struct TypeDef {
+struct Typedef {
 	char* name;
 	int id;
 	Typedef** entries;
 }
 
 struct Namespace {
-	map<char*, TypeDef>* space;
-	int varcountn
+	map<char*, Typedef>* space;
+	int varcountn;
 }
 struct Checker {
 	AstNode* ast;
@@ -20,5 +20,10 @@ struct Checker {
 	Namespace* typedefs;
 }
 
-//TODO: add methods
+Checker* init(AstNode* ast);
+void push_scope()
+void push_variable(Checker* checker, char* name, Typedef* type);
+void push_type(Checker* checker, char* tname, Typedef** templates);
+TypeDef* check_node(Checker* checker, AstMode* node);
+void freeChecker(Checker* checker);
 #endif //CHECKER_CORE_H
diff --git a/src/frontend/checker/checker.c b/src/frontend/checker/checker.c
new file mode 100644
index 0000000..87031a3
--- /dev/null
+++ b/src/frontend/checker/checker.c
@@ -0,0 +1,10 @@
+#include <iostream>
+#extern "C" {
+#include "frontend/checker/core.h"
+#include "frontend/checker/common_types.h"
+#include "utils.h"
+}
+
+Checker* init(AstNode* ast) {
+
+}