Index: src/Validate/ReplacePseudoFunc.cpp
===================================================================
--- src/Validate/ReplacePseudoFunc.cpp	(revision f2898df1db5cd1f1673c3aaa39bc475f81adb6e2)
+++ src/Validate/ReplacePseudoFunc.cpp	(revision f2898df1db5cd1f1673c3aaa39bc475f81adb6e2)
@@ -0,0 +1,50 @@
+#include "AST/Decl.hpp"
+#include "AST/Pass.hpp"
+#include "AST/Stmt.hpp"
+#include "AST/Inspect.hpp"
+#include "Common/utility.h"
+#include "ReplacePseudoFunc.hpp"
+
+namespace Validate {
+
+namespace {
+
+struct ReplacePseudoFuncCore {
+    ast::Expr const * postvisit( ast::ApplicationExpr const * decl );
+};
+}
+
+ast::Expr const * ReplacePseudoFuncCore::postvisit( ast::ApplicationExpr const * expr) {
+    auto fname = ast::getFunctionName( expr );
+    if ( fname == "posE" ) {
+        // std::cerr << "Found App in ReplacePseudoFunc" << std::endl;
+        if ( expr->args.size() != 1 ) {
+            SemanticError( expr, "Position Expression only take one parameter" );
+        }
+        const ast::VariableExpr * arg = expr->args.front().as<const ast::VariableExpr>();
+        if ( !arg ) {
+            SemanticError( expr, "Unimplement Pseudo Function Cases" );
+        }
+        const ast::ObjectDecl * argAsVar = arg->var.as<const ast::ObjectDecl>();
+        const std::string referredName = argAsVar->name;
+        const ast::EnumInstType * argType = argAsVar->type.as<const ast::EnumInstType>();
+        if ( !argType ) {
+            SemanticError( argAsVar, "Position can only be used on an enumeration instance" );
+        }
+        const ast::EnumDecl * base = argType->base;
+        for ( size_t i = 0; i < base->members.size(); i++ ) {
+            if ( base->members[i]->name == referredName ) {
+                return ast::ConstantExpr::from_int( expr->location, i );
+            }
+        }
+    }
+    return expr;
+}
+
+
+
+void replacePseudoFunc( ast::TranslationUnit & translationUnit ) {
+    ast::Pass<ReplacePseudoFuncCore>::run( translationUnit );
+}
+
+}
Index: src/Validate/ReplacePseudoFunc.hpp
===================================================================
--- src/Validate/ReplacePseudoFunc.hpp	(revision f2898df1db5cd1f1673c3aaa39bc475f81adb6e2)
+++ src/Validate/ReplacePseudoFunc.hpp	(revision f2898df1db5cd1f1673c3aaa39bc475f81adb6e2)
@@ -0,0 +1,10 @@
+#pragma once
+
+namespace ast {
+    class TranslationUnit;
+}
+
+namespace Validate {
+
+void replacePseudoFunc( ast::TranslationUnit & translationUnit );
+}