diff --git a/nac3artiq/src/symbol_resolver.rs b/nac3artiq/src/symbol_resolver.rs
index e420bd8..1652509 100644
--- a/nac3artiq/src/symbol_resolver.rs
+++ b/nac3artiq/src/symbol_resolver.rs
@@ -2,7 +2,7 @@ use inkwell::{types::BasicType, values::BasicValueEnum, AddressSpace};
 use nac3core::{
     codegen::CodeGenContext,
     location::Location,
-    symbol_resolver::SymbolResolver,
+    symbol_resolver::{SymbolResolver, SymbolValue},
     toplevel::{DefinitionId, TopLevelDef},
     typecheck::{
         type_inferencer::PrimitiveStore,
@@ -14,7 +14,7 @@ use pyo3::{
     types::{PyList, PyModule, PyTuple},
     PyAny, PyObject, PyResult, Python,
 };
-use nac3parser::ast::StrRef;
+use nac3parser::ast::{self, StrRef};
 use std::{
     cell::RefCell,
     collections::{HashMap, HashSet},
@@ -399,9 +399,86 @@ impl Resolver {
             }
         }
     }
+
+    fn get_default_param_obj_value(&self, obj: &PyAny, helper: &PythonHelper) -> PyResult<Result<SymbolValue, String>> {
+        let ty_id: u64 = helper
+            .id_fn
+            .call1((helper.type_fn.call1((obj,))?,))?
+            .extract()?;
+        Ok(
+            if ty_id == self.primitive_ids.int || ty_id == self.primitive_ids.int32 {
+                let val: i32 = obj.extract()?;
+                Ok(SymbolValue::I32(val))
+            } else if ty_id == self.primitive_ids.int64 {
+                let val: i64 = obj.extract()?;
+                Ok(SymbolValue::I64(val))
+            } else if ty_id == self.primitive_ids.bool {
+                let val: bool = obj.extract()?;
+                Ok(SymbolValue::Bool(val))
+            } else if ty_id == self.primitive_ids.float {
+                let val: f64 = obj.extract()?;
+                Ok(SymbolValue::Double(val))
+            } else if ty_id == self.primitive_ids.tuple {
+                let elements: &PyTuple = obj.cast_as()?;
+                let elements: Result<Result<Vec<_>, String>, _> = elements
+                    .iter()
+                    .map(|elem| {
+                        self.get_default_param_obj_value(
+                            elem,
+                            helper
+                        )
+                    })
+                    .collect();
+                let elements = match elements? {
+                    Ok(el) => el,
+                    Err(err) => return Ok(Err(err))
+                };
+                Ok(SymbolValue::Tuple(elements))
+            } else {
+                Err("only primitives values and tuple can be default parameter value".into())
+            }
+        )
+    }
 }
 
 impl SymbolResolver for Resolver {
+    fn get_default_param_value(
+        &self,
+        expr: &ast::Expr
+    ) -> Option<SymbolValue> {
+        match &expr.node {
+            ast::ExprKind::Name { id, .. } => {
+                Python::with_gil(
+                    |py| -> PyResult<Option<SymbolValue>> {
+                        let obj: &PyAny = self.module.extract(py)?;
+                        let members: &PyList = PyModule::import(py, "inspect")?
+                            .getattr("getmembers")?
+                            .call1((obj,))?
+                            .cast_as()?;
+                        let mut sym_value = None;
+                        for member in members.iter() {
+                            let key: &str = member.get_item(0)?.extract()?;
+                            let val = member.get_item(1)?;
+                            if key == id.to_string() {
+                                let builtins = PyModule::import(py, "builtins")?;
+                                let helper = PythonHelper {
+                                    id_fn: builtins.getattr("id").unwrap(),
+                                    len_fn: builtins.getattr("len").unwrap(),
+                                    type_fn: builtins.getattr("type").unwrap(),
+                                };
+                                sym_value = Some(self.get_default_param_obj_value(val, &helper).unwrap().unwrap());
+                                break;
+                            }
+                        }
+                        Ok(sym_value)
+                    }
+                )
+                .unwrap()
+            }
+            _ => unimplemented!("other type of expr not supported at {}", expr.location)
+        }
+    }
+
     fn get_symbol_type(
         &self,
         unifier: &mut Unifier,
diff --git a/nac3core/src/codegen/test.rs b/nac3core/src/codegen/test.rs
index ce958ff..f9e2810 100644
--- a/nac3core/src/codegen/test.rs
+++ b/nac3core/src/codegen/test.rs
@@ -37,6 +37,10 @@ impl Resolver {
 }
 
 impl SymbolResolver for Resolver {
+    fn get_default_param_value(&self, _: &nac3parser::ast::Expr) -> Option<crate::symbol_resolver::SymbolValue> {
+        unimplemented!()
+    }
+    
     fn get_symbol_type(
         &self,
         _: &mut Unifier,
diff --git a/nac3core/src/symbol_resolver.rs b/nac3core/src/symbol_resolver.rs
index 161d78a..e8d594d 100644
--- a/nac3core/src/symbol_resolver.rs
+++ b/nac3core/src/symbol_resolver.rs
@@ -44,6 +44,7 @@ pub trait SymbolResolver {
         ctx: &mut CodeGenContext<'ctx, 'a>,
     ) -> Option<BasicValueEnum<'ctx>>;
     fn get_symbol_location(&self, str: StrRef) -> Option<Location>;
+    fn get_default_param_value(&self, expr: &nac3parser::ast::Expr) -> Option<SymbolValue>;
     // handle function call etc.
 }
 
diff --git a/nac3core/src/toplevel/composer.rs b/nac3core/src/toplevel/composer.rs
index 1cb1680..232e0c4 100644
--- a/nac3core/src/toplevel/composer.rs
+++ b/nac3core/src/toplevel/composer.rs
@@ -1136,7 +1136,7 @@ impl TopLevelComposer {
                                     default_value: match default {
                                         None => None,
                                         Some(default) =>
-                                            Some(Self::parse_parameter_default_value(default)?)
+                                            Some(Self::parse_parameter_default_value(default, resolver)?)
                                     }
                                 })
                             })
@@ -1353,7 +1353,7 @@ impl TopLevelComposer {
                                             if name == "self".into() {
                                                 return Err(format!("`self` parameter cannot take default value at {}", x.location));
                                             }
-                                            Some(Self::parse_parameter_default_value(default)?)
+                                            Some(Self::parse_parameter_default_value(default, class_resolver)?)
                                         }
                                     }
                                 };
diff --git a/nac3core/src/toplevel/helper.rs b/nac3core/src/toplevel/helper.rs
index 397a10d..6d46d9d 100644
--- a/nac3core/src/toplevel/helper.rs
+++ b/nac3core/src/toplevel/helper.rs
@@ -347,51 +347,64 @@ impl TopLevelComposer {
         Ok(result)
     }
 
-    pub fn parse_parameter_default_value(default: &ast::Expr) -> Result<SymbolValue, String> {
-        fn handle_constant(val: &Constant, loc: &Location) -> Result<SymbolValue, String> {
-            match val {
-                Constant::Int(v) => {
-                    if let Ok(v) = v.try_into() {
-                        Ok(SymbolValue::I32(v))
-                    } else {
-                        Err(format!(
-                            "int64 default parameter should be specified explicitly by `int64()` at {}",
-                            loc
-                        ))
-                    }
-                }
-                Constant::Float(v) => Ok(SymbolValue::Double(*v)),
-                Constant::Bool(v) => Ok(SymbolValue::Bool(*v)),
-                Constant::Tuple(tuple) => Ok(SymbolValue::Tuple(
-                    tuple.iter().map(|x| handle_constant(x, loc)).collect::<Result<Vec<_>, _>>()?
-                )),
-                _ => unimplemented!("this constant is not supported at {}", loc),
-            }
-        }
-        match &default.node {
-            ast::ExprKind::Constant { value, .. } => handle_constant(value, &default.location),
-            ast::ExprKind::Call { func, args, .. } if {
-                match &func.node {
-                    ast::ExprKind::Name { id, .. } => *id == "int64".into(),
-                    _ => false,
-                }
-            } => {
-                if args.len() == 1 {
-                    match &args[0].node {
-                        ast::ExprKind::Constant { value: Constant::Int(v), .. } =>
-                            Ok(SymbolValue::I64(v.try_into().unwrap())),
-                        _ => Err(format!("only allow constant integer here at {}", default.location))
-                    }
-                } else {
-                    Err(format!("only allow constant integer here at {}", default.location))
-                }
-            }
-            ast::ExprKind::Tuple { elts, .. } => Ok(SymbolValue::Tuple(elts
-                .iter()
-                .map(|x| Self::parse_parameter_default_value(x))
-                .collect::<Result<Vec<_>, _>>()?
-            )),
-            _ => unimplemented!("only constant default is supported now at {}", default.location),
-        }
+    pub fn parse_parameter_default_value(default: &ast::Expr, resolver: &(dyn SymbolResolver + Send + Sync)) -> Result<SymbolValue, String> {
+        parse_parameter_default_value(default, resolver)
+    }
+}
+
+pub fn parse_parameter_default_value(default: &ast::Expr, resolver: &(dyn SymbolResolver + Send + Sync)) -> Result<SymbolValue, String> {
+    fn handle_constant(val: &Constant, loc: &Location) -> Result<SymbolValue, String> {
+        match val {
+            Constant::Int(v) => {
+                if let Ok(v) = v.try_into() {
+                    Ok(SymbolValue::I32(v))
+                } else {
+                    Err(format!(
+                        "int64 default parameter should be specified explicitly by `int64()` at {}",
+                        loc
+                    ))
+                }
+            }
+            Constant::Float(v) => Ok(SymbolValue::Double(*v)),
+            Constant::Bool(v) => Ok(SymbolValue::Bool(*v)),
+            Constant::Tuple(tuple) => Ok(SymbolValue::Tuple(
+                tuple.iter().map(|x| handle_constant(x, loc)).collect::<Result<Vec<_>, _>>()?
+            )),
+            _ => unimplemented!("this constant is not supported at {}", loc),
+        }
+    }
+    match &default.node {
+        ast::ExprKind::Constant { value, .. } => handle_constant(value, &default.location),
+        ast::ExprKind::Call { func, args, .. } if {
+            match &func.node {
+                ast::ExprKind::Name { id, .. } => *id == "int64".into(),
+                _ => false,
+            }
+        } => {
+            if args.len() == 1 {
+                match &args[0].node {
+                    ast::ExprKind::Constant { value: Constant::Int(v), .. } =>
+                        Ok(SymbolValue::I64(v.try_into().unwrap())),
+                    _ => Err(format!("only allow constant integer here at {}", default.location))
+                }
+            } else {
+                Err(format!("only allow constant integer here at {}", default.location))
+            }
+        }
+        ast::ExprKind::Tuple { elts, .. } => Ok(SymbolValue::Tuple(elts
+            .iter()
+            .map(|x| parse_parameter_default_value(x, resolver))
+            .collect::<Result<Vec<_>, _>>()?
+        )),
+        ast::ExprKind::Name { id, .. } => {
+            resolver.get_default_param_value(default).ok_or_else(
+                || format!(
+                    "this module global `{}` cannot be used as a default parameter at {} (should be primitive type or tuple)",
+                    id,
+                    default.location
+                )
+            )
+        }
+        _ => unimplemented!("only constant default is supported now at {}", default.location),
     }
 }
diff --git a/nac3core/src/toplevel/mod.rs b/nac3core/src/toplevel/mod.rs
index c96a7ca..f6fc15b 100644
--- a/nac3core/src/toplevel/mod.rs
+++ b/nac3core/src/toplevel/mod.rs
@@ -23,7 +23,7 @@ use inkwell::values::BasicValueEnum;
 pub struct DefinitionId(pub usize);
 
 pub mod composer;
-mod helper;
+pub mod helper;
 mod type_annotation;
 use composer::*;
 use type_annotation::*;
diff --git a/nac3core/src/toplevel/test.rs b/nac3core/src/toplevel/test.rs
index e279547..0f4fd83 100644
--- a/nac3core/src/toplevel/test.rs
+++ b/nac3core/src/toplevel/test.rs
@@ -35,6 +35,10 @@ impl ResolverInternal {
 struct Resolver(Arc<ResolverInternal>);
 
 impl SymbolResolver for Resolver {
+    fn get_default_param_value(&self, _: &nac3parser::ast::Expr) -> Option<crate::symbol_resolver::SymbolValue> {
+        unimplemented!()
+    }
+    
     fn get_symbol_type(
         &self,
         _: &mut Unifier,
diff --git a/nac3core/src/typecheck/type_inferencer/test.rs b/nac3core/src/typecheck/type_inferencer/test.rs
index d3aa09f..da51aa9 100644
--- a/nac3core/src/typecheck/type_inferencer/test.rs
+++ b/nac3core/src/typecheck/type_inferencer/test.rs
@@ -19,6 +19,10 @@ struct Resolver {
 }
 
 impl SymbolResolver for Resolver {
+    fn get_default_param_value(&self, _: &nac3parser::ast::Expr) -> Option<crate::symbol_resolver::SymbolValue> {
+        unimplemented!()
+    }
+    
     fn get_symbol_type(
         &self,
         _: &mut Unifier,
diff --git a/nac3standalone/src/basic_symbol_resolver.rs b/nac3standalone/src/basic_symbol_resolver.rs
index 82c1ac3..31b3713 100644
--- a/nac3standalone/src/basic_symbol_resolver.rs
+++ b/nac3standalone/src/basic_symbol_resolver.rs
@@ -2,21 +2,22 @@ use inkwell::values::BasicValueEnum;
 use nac3core::{
     codegen::CodeGenContext,
     location::Location,
-    symbol_resolver::SymbolResolver,
-    toplevel::{DefinitionId, TopLevelDef},
+    symbol_resolver::{SymbolResolver, SymbolValue},
+    toplevel::{DefinitionId, TopLevelDef, helper::parse_parameter_default_value},
     typecheck::{
         type_inferencer::PrimitiveStore,
         typedef::{Type, Unifier},
     },
 };
 use parking_lot::{Mutex, RwLock};
-use nac3parser::ast::StrRef;
+use nac3parser::ast::{self, StrRef};
 use std::{collections::HashMap, sync::Arc};
 
 pub struct ResolverInternal {
     pub id_to_type: Mutex<HashMap<StrRef, Type>>,
     pub id_to_def: Mutex<HashMap<StrRef, DefinitionId>>,
     pub class_names: Mutex<HashMap<StrRef, Type>>,
+    pub module_globals: Mutex<HashMap<StrRef, ast::Expr>>,
 }
 
 impl ResolverInternal {
@@ -27,11 +28,27 @@ impl ResolverInternal {
     pub fn add_id_type(&self, id: StrRef, ty: Type) {
         self.id_to_type.lock().insert(id, ty);
     }
+
+    pub fn add_module_global(&self, id: StrRef, expr: &ast::Expr) {
+        self.module_globals.lock().insert(id, expr.clone());
+    }
 }
 
 pub struct Resolver(pub Arc<ResolverInternal>);
 
 impl SymbolResolver for Resolver {
+    fn get_default_param_value(&self, expr: &ast::Expr) -> Option<SymbolValue> {
+        match &expr.node {
+            ast::ExprKind::Name { id, .. } => {
+                let expr = self.0.module_globals.lock().get(id).cloned();
+                expr.map(|x| {
+                    parse_parameter_default_value(&x, self).unwrap()
+                })
+            }
+            _ => unimplemented!("other type of expr not supported at {}", expr.location)
+        }
+    }
+
     fn get_symbol_type(
         &self,
         _: &mut Unifier,
diff --git a/nac3standalone/src/main.rs b/nac3standalone/src/main.rs
index 5b4e31d..33fc0e6 100644
--- a/nac3standalone/src/main.rs
+++ b/nac3standalone/src/main.rs
@@ -4,7 +4,7 @@ use inkwell::{
     OptimizationLevel,
 };
 use nac3core::typecheck::type_inferencer::PrimitiveStore;
-use nac3parser::parser;
+use nac3parser::{ast::{ExprKind, StmtKind}, parser};
 use std::env;
 use std::fs;
 use std::{collections::HashMap, path::Path, sync::Arc, time::SystemTime};
@@ -48,6 +48,7 @@ fn main() {
         id_to_type: builtins_ty.into(),
         id_to_def: builtins_def.into(),
         class_names: Default::default(),
+        module_globals: Default::default(),
     }
     .into();
     let resolver =
@@ -66,6 +67,18 @@ fn main() {
     );
 
     for stmt in parser_result.into_iter() {
+        // handle module globals
+        if let StmtKind::Assign { targets, value, .. } = &stmt.node {
+            if targets.len() == 1 {
+                if let ExprKind::Name { id, .. } = &targets[0].node {
+                    internal_resolver.add_module_global(*id, value);
+                }
+            } else {
+                unimplemented!("only single assign supported now")
+            }
+            continue;
+        }
+
         let (name, def_id, ty) = composer
             .register_top_level(stmt, Some(resolver.clone()), "__main__".into())
             .unwrap();