Merge branch 'master' into KernelInvariant

.cargo/config

@@ -1,2 +0,0 @@
-[unstable]
-extra-link-arg = true

flake.lock

@@ -2,16 +2,16 @@
   "nodes": {
     "nixpkgs": {
       "locked": {
-        "lastModified": 1636698608,
+        "lastModified": 1637636156,
-        "narHash": "sha256-sxLLeQmH3UrP3UANqXzMLE0bPDgY5aIt04iBoPffG2E=",
+        "narHash": "sha256-E2ym4Vcpqu9JYoQDXJZR48gVD+LPPbaCoYveIk7Xu3Y=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "92c881b6a72abce5bb2f5db3f903b4871d13aaa9",
+        "rev": "b026e1cf87a108dd06fe521f224fdc72fd0b013d",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "master",
+        "ref": "release-21.11",
         "repo": "nixpkgs",
         "type": "github"
       }

flake.nix

@@ -1,7 +1,7 @@
 {
   description = "The third-generation ARTIQ compiler";
 
-  inputs.nixpkgs.url = github:NixOS/nixpkgs/master;
+  inputs.nixpkgs.url = github:NixOS/nixpkgs/release-21.11;
 
   outputs = { self, nixpkgs }:
     let

nac3artiq/src/symbol_resolver.rs

@@ -2,14 +2,14 @@ use inkwell::{types::BasicType, values::BasicValueEnum, AddressSpace};
 use nac3core::{
     codegen::CodeGenContext,
     location::Location,
-    symbol_resolver::{StaticValue, SymbolResolver, ValueEnum},
+    symbol_resolver::{StaticValue, SymbolResolver, SymbolValue, ValueEnum},
     toplevel::{DefinitionId, TopLevelDef},
     typecheck::{
         type_inferencer::PrimitiveStore,
         typedef::{Type, TypeEnum, Unifier},
     },
 };
-use nac3parser::ast::StrRef;
+use nac3parser::ast::{self, StrRef};
 use parking_lot::{Mutex, RwLock};
 use pyo3::{
     types::{PyList, PyModule, PyTuple},
@@ -458,9 +458,80 @@ impl InnerResolver {
             }
         }
     }
+
+    fn get_default_param_obj_value(
+        &self,
+        py: Python,
+        obj: &PyAny,
+    ) -> PyResult<Result<SymbolValue, String>> {
+        let ty_id: u64 = self
+            .helper
+            .id_fn
+            .call1(py, (self.helper.type_fn.call1(py, (obj,))?,))?
+            .extract(py)?;
+        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(py, elem))
+                    .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.0.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() {
+                            sym_value = Some(
+                                self.0
+                                    .get_default_param_obj_value(py, val)
+                                    .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,

nac3core/src/codegen/concrete_type.rs

@@ -147,8 +147,15 @@ impl ConcreteTypeStore {
                     fields: fields
                         .borrow()
                         .iter()
-                        .map(|(name, ty)| {
+                        .filter_map(|(name, ty)| {
-                            (*name, (self.from_unifier_type(unifier, primitives, ty.0, cache), ty.1))
+                            // here we should not have type vars, but some partial instantiated
+                            // class methods can still have uninstantiated type vars, so
+                            // filter out all the methods, as this will not affect codegen
+                            if let TypeEnum::TFunc( .. ) = &*unifier.get_ty(ty.0) {
+                                None
+                            } else {
+                                Some((*name, (self.from_unifier_type(unifier, primitives, ty.0, cache), ty.1)))
+                            }
                         })
                         .collect(),
                     params: params

nac3core/src/codegen/expr.rs

@@ -7,7 +7,7 @@ use crate::{
     },
     symbol_resolver::{SymbolValue, ValueEnum},
     toplevel::{DefinitionId, TopLevelDef},
-    typecheck::typedef::{FunSignature, FuncArg, Type, TypeEnum},
+    typecheck::typedef::{FunSignature, FuncArg, Type, TypeEnum, Unifier},
 };
 use inkwell::{
     types::{BasicType, BasicTypeEnum},
@@ -19,6 +19,31 @@ use nac3parser::ast::{self, Boolop, Comprehension, Constant, Expr, ExprKind, Ope
 
 use super::CodeGenerator;
 
+pub fn get_subst_key(
+    unifier: &mut Unifier,
+    obj: Option<Type>,
+    fun_vars: &HashMap<u32, Type>,
+    filter: Option<&Vec<u32>>,
+) -> String {
+    let mut vars = obj
+        .map(|ty| {
+            if let TypeEnum::TObj { params, .. } = &*unifier.get_ty(ty) {
+                params.borrow().clone()
+            } else {
+                unreachable!()
+            }
+        })
+        .unwrap_or_default();
+    vars.extend(fun_vars.iter());
+    let sorted =
+        vars.keys().filter(|id| filter.map(|v| v.contains(id)).unwrap_or(true)).sorted();
+    sorted
+        .map(|id| {
+            unifier.stringify(vars[id], &mut |id| id.to_string(), &mut |id| id.to_string())
+        })
+        .join(", ")
+}
+
 impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
     pub fn build_gep_and_load(
         &mut self,
@@ -34,23 +59,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
         fun: &FunSignature,
         filter: Option<&Vec<u32>>,
     ) -> String {
-        let mut vars = obj
+        get_subst_key(&mut self.unifier, obj, &fun.vars, filter)
-            .map(|ty| {
-                if let TypeEnum::TObj { params, .. } = &*self.unifier.get_ty(ty) {
-                    params.borrow().clone()
-                } else {
-                    unreachable!()
-                }
-            })
-            .unwrap_or_default();
-        vars.extend(fun.vars.iter());
-        let sorted =
-            vars.keys().filter(|id| filter.map(|v| v.contains(id)).unwrap_or(true)).sorted();
-        sorted
-            .map(|id| {
-                self.unifier.stringify(vars[id], &mut |id| id.to_string(), &mut |id| id.to_string())
-            })
-            .join(", ")
     }
 
     pub fn get_attr_index(&mut self, ty: Type, attr: StrRef) -> usize {

nac3core/src/codegen/mod.rs

@@ -293,7 +293,14 @@ pub fn gen_func<'ctx, G: CodeGenerator + ?Sized>(
         // this should be unification between variables and concrete types
         // and should not cause any problem...
         let b = task.store.to_unifier_type(&mut unifier, &primitives, *b, &mut cache);
-        unifier.unify(*a, b).unwrap();
+        unifier.unify(*a, b).or_else(|err| {
+            if matches!(&*unifier.get_ty(*a), TypeEnum::TRigidVar { .. }) {
+                unifier.replace_rigid_var(*a, b);
+                Ok(())
+            } else {
+                Err(err)
+            }
+        }).unwrap()
     }
 
     // rebuild primitive store with unique representatives

nac3core/src/codegen/test.rs

@@ -36,6 +36,10 @@ 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,

nac3core/src/symbol_resolver.rs

@@ -102,6 +102,7 @@ pub trait SymbolResolver {
     ) -> Option<ValueEnum<'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.
 }
 

nac3core/src/toplevel/composer.rs

@@ -6,6 +6,7 @@ use inkwell::FloatPredicate;
 use crate::{
     symbol_resolver::SymbolValue,
     typecheck::type_inferencer::{FunctionData, Inferencer},
+    codegen::expr::get_subst_key,
 };
 
 use super::*;
@@ -194,7 +195,7 @@ impl TopLevelComposer {
                     signature: primitives.1.add_ty(TypeEnum::TFunc(RefCell::new(FunSignature {
                         args: vec![FuncArg { name: "_".into(), ty: num_ty.0, default_value: None }],
                         ret: float,
-                        vars: var_map,
+                        vars: var_map.clone(),
                     }))),
                     var_id: Default::default(),
                     instance_to_symbol: Default::default(),
@@ -397,7 +398,7 @@ impl TopLevelComposer {
                     signature: primitives.1.add_ty(TypeEnum::TFunc(RefCell::new(FunSignature {
                         args: vec![FuncArg { name: "_".into(), ty: num_ty.0, default_value: None }],
                         ret: primitives.0.bool,
-                        vars: Default::default(),
+                        vars: var_map,
                     }))),
                     var_id: Default::default(),
                     instance_to_symbol: Default::default(),
@@ -1066,9 +1067,22 @@ impl TopLevelComposer {
                                 .into());
                         }
 
-                        args.args
+                        let arg_with_default: Vec<(&ast::Located<ast::ArgData<()>>, Option<&ast::Expr>)> = args
+                            .args
                             .iter()
-                            .map(|x| -> Result<FuncArg, String> {
+                            .rev()
+                            .zip(args
+                                .defaults
+                                .iter()
+                                .rev()
+                                .map(|x| -> Option<&ast::Expr> { Some(x) })
+                                .chain(std::iter::repeat(None))
+                            ).collect_vec();
+
+                        arg_with_default
+                            .iter()
+                            .rev()
+                            .map(|(x, default)| -> Result<FuncArg, String> {
                                 let annotation = x
                                     .node
                                     .annotation
@@ -1120,7 +1134,19 @@ impl TopLevelComposer {
                                 Ok(FuncArg {
                                     name: x.node.arg,
                                     ty,
-                                    default_value: Default::default(),
+                                    default_value: match default {
+                                        None => None,
+                                        Some(default) => Some({
+                                            let v = Self::parse_parameter_default_value(default, resolver)?;
+                                            Self::check_default_param_type(
+                                                &v,
+                                                &type_annotation,
+                                                primitives_store,
+                                                unifier
+                                            ).map_err(|err| format!("{} at {}", err, x.location))?;
+                                            v
+                                        })
+                                    }
                                 })
                             })
                             .collect::<Result<Vec<_>, _>>()?
@@ -1170,8 +1196,17 @@ impl TopLevelComposer {
                             primitives_store.none
                         }
                     };
-                    var_id.extend_from_slice(
+                    var_id.extend_from_slice(function_var_map
-                        function_var_map.keys().into_iter().copied().collect_vec().as_slice(),
+                        .iter()
+                        .filter_map(|(id, ty)| {
+                            if matches!(&*unifier.get_ty(*ty), TypeEnum::TVar { range, .. } if range.borrow().is_empty()) {
+                                None
+                            } else {
+                                Some(*id)
+                            }
+                        })
+                        .collect_vec()
+                        .as_slice()
                     );
                     let function_ty = unifier.add_ty(TypeEnum::TFunc(
                         FunSignature { args: arg_types, ret: return_ty, vars: function_var_map }
@@ -1272,7 +1307,20 @@ impl TopLevelComposer {
                         }
 
                         let mut result = Vec::new();
-                        for x in &args.args {
+
+                        let arg_with_default: Vec<(&ast::Located<ast::ArgData<()>>, Option<&ast::Expr>)> = args
+                            .args
+                            .iter()
+                            .rev()
+                            .zip(args
+                                .defaults
+                                .iter()
+                                .rev()
+                                .map(|x| -> Option<&ast::Expr> { Some(x) })
+                                .chain(std::iter::repeat(None))
+                            ).collect_vec();
+
+                        for (x, default) in arg_with_default.into_iter().rev() {
                             let name = x.node.arg;
                             if name != zelf {
                                 let type_ann = {
@@ -1317,8 +1365,20 @@ impl TopLevelComposer {
                                 let dummy_func_arg = FuncArg {
                                     name,
                                     ty: unifier.get_fresh_var().0,
-                                    // TODO: default value?
+                                    default_value: match default {
-                                    default_value: None,
+                                        None => None,
+                                        Some(default) => {
+                                            if name == "self".into() {
+                                                return Err(format!("`self` parameter cannot take default value at {}", x.location));
+                                            }
+                                            Some({
+                                                let v = Self::parse_parameter_default_value(default, class_resolver)?;
+                                                Self::check_default_param_type(&v, &type_ann, primitives, unifier)
+                                                    .map_err(|err| format!("{} at {}", err, x.location))?;
+                                                v
+                                            })
+                                        }
+                                    }
                                 };
                                 // push the dummy type and the type annotation
                                 // into the list for later unification
@@ -1374,9 +1434,20 @@ impl TopLevelComposer {
                     if let TopLevelDef::Function { var_id, .. } =
                         temp_def_list.get(method_id.0).unwrap().write().deref_mut()
                     {
-                        var_id.extend_from_slice(
+                        var_id.extend_from_slice(method_var_map
-                            method_var_map.keys().into_iter().copied().collect_vec().as_slice(),
+                            .iter()
+                            .filter_map(|(id, ty)| {
+                                if matches!(&*unifier.get_ty(*ty), TypeEnum::TVar { range, .. } if range.borrow().is_empty()) {
+                                    None
+                                } else {
+                                    Some(*id)
+                                }
+                            })
+                            .collect_vec()
+                            .as_slice()
                         );
+                    } else {
+                        unreachable!()
                     }
                     let method_type = unifier.add_ty(TypeEnum::TFunc(
                         FunSignature { args: arg_types, ret: ret_type, vars: method_var_map }
@@ -1625,9 +1696,11 @@ impl TopLevelComposer {
                             unreachable!("must be init function here")
                         }
                         let all_inited = Self::get_all_assigned_field(body.as_slice())?;
-                        if fields.iter().any(|x| !all_inited.contains(&x.0)) {
+                        for (f, _, _) in fields {
+                            if !all_inited.contains(f) {
                                 return Err(format!(
-                                "fields of class {} not fully initialized",
+                                    "fields `{}` of class `{}` not fully initialized",
+                                    f,
                                     class_name
                                 ));
                             }
@@ -1635,6 +1708,7 @@ impl TopLevelComposer {
                     }
                 }
             }
+        }
 
         let ctx = Arc::new(self.make_top_level_context());
         // type inference inside function body
@@ -1648,13 +1722,14 @@ impl TopLevelComposer {
                 simple_name,
                 signature,
                 resolver,
+                var_id: insted_vars,
                 ..
             } = &mut *function_def
             {
                 if let TypeEnum::TFunc(func_sig) = self.unifier.get_ty(*signature).as_ref() {
                     let FunSignature { args, ret, vars } = &*func_sig.borrow();
                     // None if is not class method
-                    let self_type = {
+                    let uninst_self_type = {
                         if let Some(class_id) = self.method_class.get(&DefinitionId(id)) {
                             let class_def = self.definition_ast_list.get(class_id.0).unwrap();
                             let class_def = class_def.0.read();
@@ -1666,7 +1741,7 @@ impl TopLevelComposer {
                                     &self.primitives_ty,
                                     &ty_ann,
                                 )?;
-                                Some(self_ty)
+                                Some((self_ty, type_vars.clone()))
                             } else {
                                 unreachable!("must be class def")
                             }
@@ -1674,20 +1749,20 @@ impl TopLevelComposer {
                             None
                         }
                     };
+                    // carefully handle those with bounds, without bounds and no typevars
+                    // if class methods, `vars` also contains all class typevars here
                     let (type_var_subst_comb, no_range_vars) = {
                         let unifier = &mut self.unifier;
                         let mut no_ranges: Vec<Type> = Vec::new();
-                        let var_ids = vars.iter().map(|(id, ty)| {
+                        let var_ids = vars.keys().copied().collect_vec();
-                            if matches!(unifier.get_ty(*ty).as_ref(), TypeEnum::TVar { range, .. } if range.borrow().is_empty()) {
-                                no_ranges.push(*ty);
-                            }
-                            *id
-                        })
-                        .collect_vec();
                         let var_combs = vars
                             .iter()
                             .map(|(_, ty)| {
-                                unifier.get_instantiations(*ty).unwrap_or_else(|| vec![*ty])
+                                unifier.get_instantiations(*ty).unwrap_or_else(|| {
+                                    let rigid = unifier.get_fresh_rigid_var().0;
+                                    no_ranges.push(rigid);
+                                    vec![rigid]
+                                })
                             })
                             .multi_cartesian_product()
                             .collect_vec();
@@ -1717,9 +1792,34 @@ impl TopLevelComposer {
                         };
                         let self_type = {
                             let unifier = &mut self.unifier;
-                            self_type.map(|x| unifier.subst(x, &subst).unwrap_or(x))
+                            uninst_self_type
+                                .clone()
+                                .map(|(self_type, type_vars)| {
+                                    let subst_for_self = {
+                                        let class_ty_var_ids = type_vars
+                                            .iter()
+                                            .map(|x| {
+                                                if let TypeEnum::TVar { id, .. } = &*unifier.get_ty(*x) {
+                                                    *id
+                                                } else {
+                                                    unreachable!("must be type var here");
+                                                }
+                                            })
+                                            .collect::<HashSet<_>>();
+                                        subst
+                                            .iter()
+                                            .filter_map(|(ty_var_id, ty_var_target)| {
+                                                if class_ty_var_ids.contains(ty_var_id) {
+                                                    Some((*ty_var_id, *ty_var_target))
+                                                } else {
+                                                    None
+                                                }
+                                            })
+                                            .collect::<HashMap<_, _>>()
+                                    };
+                                    unifier.subst(self_type, &subst_for_self).unwrap_or(self_type)
+                                })
                         };
-
                         let mut identifiers = {
                             // NOTE: none and function args?
                             let mut result: HashSet<_> = HashSet::new();
@@ -1809,22 +1909,12 @@ impl TopLevelComposer {
                         }
 
                         instance_to_stmt.insert(
-                            // NOTE: refer to codegen/expr/get_subst_key function
+                            get_subst_key(
-                            {
+                                &mut self.unifier,
-                                let unifier = &mut self.unifier;
+                                self_type,
-                                subst
+                                &subst,
-                                    .keys()
+                                Some(insted_vars),
-                                    .sorted()
+                            ),
-                                    .map(|id| {
-                                        let ty = subst.get(id).unwrap();
-                                        unifier.stringify(
-                                            *ty,
-                                            &mut |id| id.to_string(),
-                                            &mut |id| id.to_string(),
-                                        )
-                                    })
-                                    .join(", ")
-                            },
                             FunInstance {
                                 body: Arc::new(fun_body),
                                 unifier_id: 0,

nac3core/src/toplevel/helper.rs

@@ -1,3 +1,8 @@
+use std::convert::TryInto;
+
+use nac3parser::ast::{Constant, Location};
+use crate::symbol_resolver::SymbolValue;
+
 use super::*;
 
 impl TopLevelDef {
@@ -341,4 +346,121 @@ impl TopLevelComposer {
         }
         Ok(result)
     }
+
+    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 check_default_param_type(val: &SymbolValue, ty: &TypeAnnotation, primitive: &PrimitiveStore, unifier: &mut Unifier) -> Result<(), String> {
+        let res = match val {
+            SymbolValue::Bool(..) => {
+                if matches!(ty, TypeAnnotation::Primitive(t) if *t == primitive.bool) {
+                    None
+                } else {
+                    Some("bool".to_string())
+                }
+            }
+            SymbolValue::Double(..) => {
+                if matches!(ty, TypeAnnotation::Primitive(t) if *t == primitive.float) {
+                    None
+                } else {
+                    Some("float".to_string())
+                }
+            }
+            SymbolValue::I32(..) => {
+                if matches!(ty, TypeAnnotation::Primitive(t) if *t == primitive.int32) {
+                    None
+                } else {
+                    Some("int32".to_string())
+                }
+            }
+            SymbolValue::I64(..) => {
+                if matches!(ty, TypeAnnotation::Primitive(t) if *t == primitive.int64) {
+                    None
+                } else {
+                    Some("int64".to_string())
+                }
+            }
+            SymbolValue::Tuple(elts) => {
+                if let TypeAnnotation::Tuple(elts_ty) = ty {
+                    for (e, t) in elts.iter().zip(elts_ty.iter()) {
+                        Self::check_default_param_type(e, t, primitive, unifier)?
+                    }
+                    if elts.len() != elts_ty.len() {
+                        Some(format!("tuple of length {}", elts.len()))
+                    } else {
+                        None
+                    }
+                } else {
+                    Some("tuple".to_string())
+                }
+            }
+        };
+        if let Some(found) = res {
+            Err(format!(
+                "incompatible default parameter type, expect {}, found {}",
+                ty.stringify(unifier),
+                found
+            ))
+        } else {
+            Ok(())
+        }
+    }
+}
+
+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!(
+                        "integer value out of range 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!(
+                    "`{}` cannot be used as a default parameter at {} (not primitive type or tuple / not defined?)",
+                    id,
+                    default.location
+                )
+            )
+        }
+        _ => Err(format!("unsupported default parameter at {}", default.location))
+    }
 }

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::*;

nac3core/src/toplevel/snapshots/nac3core__toplevel__test__test_analyze__generic_class.snap

@@ -9,5 +9,5 @@ expression: res_vec
     "Function {\nname: \"Generic_A.fun\",\nsig: \"fn[[a=int32], var4]\",\nvar_id: [4]\n}\n",
     "Class {\nname: \"B\",\nancestors: [\"{class: B, params: []}\"],\nfields: [\"aa\"],\nmethods: [(\"__init__\", \"fn[[], none]\"), (\"foo\", \"fn[[b=var3], none]\")],\ntype_vars: []\n}\n",
     "Function {\nname: \"B.__init__\",\nsig: \"fn[[], none]\",\nvar_id: []\n}\n",
-    "Function {\nname: \"B.foo\",\nsig: \"fn[[b=var3], none]\",\nvar_id: [3]\n}\n",
+    "Function {\nname: \"B.foo\",\nsig: \"fn[[b=var3], none]\",\nvar_id: []\n}\n",
 ]

nac3core/src/toplevel/snapshots/nac3core__toplevel__test__test_analyze__inheritance_override.snap

@@ -5,12 +5,12 @@ expression: res_vec
 ---
 [
     "Class {\nname: \"A\",\nancestors: [\"{class: A, params: [\\\"var3\\\"]}\"],\nfields: [\"a\", \"b\", \"c\"],\nmethods: [(\"__init__\", \"fn[[t=var3], none]\"), (\"fun\", \"fn[[a=int32, b=var3], list[virtual[B[4->bool]]]]\"), (\"foo\", \"fn[[c=C], none]\")],\ntype_vars: [\"var3\"]\n}\n",
-    "Function {\nname: \"A.__init__\",\nsig: \"fn[[t=var3], none]\",\nvar_id: [3]\n}\n",
+    "Function {\nname: \"A.__init__\",\nsig: \"fn[[t=var3], none]\",\nvar_id: []\n}\n",
-    "Function {\nname: \"A.fun\",\nsig: \"fn[[a=int32, b=var3], list[virtual[B[4->bool]]]]\",\nvar_id: [3]\n}\n",
+    "Function {\nname: \"A.fun\",\nsig: \"fn[[a=int32, b=var3], list[virtual[B[4->bool]]]]\",\nvar_id: []\n}\n",
-    "Function {\nname: \"A.foo\",\nsig: \"fn[[c=C], none]\",\nvar_id: [3]\n}\n",
+    "Function {\nname: \"A.foo\",\nsig: \"fn[[c=C], none]\",\nvar_id: []\n}\n",
     "Class {\nname: \"B\",\nancestors: [\"{class: B, params: [\\\"var4\\\"]}\", \"{class: A, params: [\\\"float\\\"]}\"],\nfields: [\"a\", \"b\", \"c\", \"d\"],\nmethods: [(\"__init__\", \"fn[[], none]\"), (\"fun\", \"fn[[a=int32, b=var3], list[virtual[B[4->bool]]]]\"), (\"foo\", \"fn[[c=C], none]\")],\ntype_vars: [\"var4\"]\n}\n",
     "Function {\nname: \"B.__init__\",\nsig: \"fn[[], none]\",\nvar_id: [4]\n}\n",
-    "Function {\nname: \"B.fun\",\nsig: \"fn[[a=int32, b=var3], list[virtual[B[4->bool]]]]\",\nvar_id: [3, 4]\n}\n",
+    "Function {\nname: \"B.fun\",\nsig: \"fn[[a=int32, b=var3], list[virtual[B[4->bool]]]]\",\nvar_id: [4]\n}\n",
     "Class {\nname: \"C\",\nancestors: [\"{class: C, params: []}\", \"{class: B, params: [\\\"bool\\\"]}\", \"{class: A, params: [\\\"float\\\"]}\"],\nfields: [\"a\", \"b\", \"c\", \"d\", \"e\"],\nmethods: [(\"__init__\", \"fn[[], none]\"), (\"fun\", \"fn[[a=int32, b=var3], list[virtual[B[4->bool]]]]\"), (\"foo\", \"fn[[c=C], none]\")],\ntype_vars: []\n}\n",
     "Function {\nname: \"C.__init__\",\nsig: \"fn[[], none]\",\nvar_id: []\n}\n",
 ]

nac3core/src/toplevel/snapshots/nac3core__toplevel__test__test_analyze__list_tuple_generic.snap

@@ -4,10 +4,10 @@ expression: res_vec
 
 ---
 [
-    "Function {\nname: \"foo\",\nsig: \"fn[[a=list[int32], b=tuple[var3, float]], A[3->B, 4->bool]]\",\nvar_id: [3]\n}\n",
+    "Function {\nname: \"foo\",\nsig: \"fn[[a=list[int32], b=tuple[var3, float]], A[3->B, 4->bool]]\",\nvar_id: []\n}\n",
     "Class {\nname: \"A\",\nancestors: [\"{class: A, params: [\\\"var3\\\", \\\"var4\\\"]}\"],\nfields: [\"a\", \"b\"],\nmethods: [(\"__init__\", \"fn[[v=var4], none]\"), (\"fun\", \"fn[[a=var3], var4]\")],\ntype_vars: [\"var3\", \"var4\"]\n}\n",
-    "Function {\nname: \"A.__init__\",\nsig: \"fn[[v=var4], none]\",\nvar_id: [3, 4]\n}\n",
+    "Function {\nname: \"A.__init__\",\nsig: \"fn[[v=var4], none]\",\nvar_id: [4]\n}\n",
-    "Function {\nname: \"A.fun\",\nsig: \"fn[[a=var3], var4]\",\nvar_id: [3, 4]\n}\n",
+    "Function {\nname: \"A.fun\",\nsig: \"fn[[a=var3], var4]\",\nvar_id: [4]\n}\n",
     "Function {\nname: \"gfun\",\nsig: \"fn[[a=A[3->list[float], 4->int32]], none]\",\nvar_id: []\n}\n",
     "Class {\nname: \"B\",\nancestors: [\"{class: B, params: []}\"],\nfields: [],\nmethods: [(\"__init__\", \"fn[[], none]\")],\ntype_vars: []\n}\n",
     "Function {\nname: \"B.__init__\",\nsig: \"fn[[], none]\",\nvar_id: []\n}\n",

nac3core/src/toplevel/snapshots/nac3core__toplevel__test__test_analyze__self1.snap

@@ -5,8 +5,8 @@ expression: res_vec
 ---
 [
     "Class {\nname: \"A\",\nancestors: [\"{class: A, params: [\\\"var3\\\", \\\"var4\\\"]}\"],\nfields: [\"a\", \"b\"],\nmethods: [(\"__init__\", \"fn[[a=A[3->float, 4->bool], b=B], none]\"), (\"fun\", \"fn[[a=A[3->float, 4->bool]], A[3->bool, 4->int32]]\")],\ntype_vars: [\"var3\", \"var4\"]\n}\n",
-    "Function {\nname: \"A.__init__\",\nsig: \"fn[[a=A[3->float, 4->bool], b=B], none]\",\nvar_id: [3, 4]\n}\n",
+    "Function {\nname: \"A.__init__\",\nsig: \"fn[[a=A[3->float, 4->bool], b=B], none]\",\nvar_id: [4]\n}\n",
-    "Function {\nname: \"A.fun\",\nsig: \"fn[[a=A[3->float, 4->bool]], A[3->bool, 4->int32]]\",\nvar_id: [3, 4]\n}\n",
+    "Function {\nname: \"A.fun\",\nsig: \"fn[[a=A[3->float, 4->bool]], A[3->bool, 4->int32]]\",\nvar_id: [4]\n}\n",
     "Class {\nname: \"B\",\nancestors: [\"{class: B, params: []}\", \"{class: A, params: [\\\"int64\\\", \\\"bool\\\"]}\"],\nfields: [\"a\", \"b\"],\nmethods: [(\"__init__\", \"fn[[], none]\"), (\"fun\", \"fn[[a=A[3->float, 4->bool]], A[3->bool, 4->int32]]\"), (\"foo\", \"fn[[b=B], B]\"), (\"bar\", \"fn[[a=A[3->list[B], 4->int32]], tuple[A[3->virtual[A[3->B, 4->int32]], 4->bool], B]]\")],\ntype_vars: []\n}\n",
     "Function {\nname: \"B.__init__\",\nsig: \"fn[[], none]\",\nvar_id: []\n}\n",
     "Function {\nname: \"B.foo\",\nsig: \"fn[[b=B], B]\",\nvar_id: []\n}\n",

nac3core/src/toplevel/snapshots/nac3core__toplevel__test__test_analyze__simple_class_compose.snap

@@ -7,12 +7,12 @@ expression: res_vec
     "Class {\nname: \"A\",\nancestors: [\"{class: A, params: []}\"],\nfields: [\"a\"],\nmethods: [(\"__init__\", \"fn[[], none]\"), (\"fun\", \"fn[[b=B], none]\"), (\"foo\", \"fn[[a=var3, b=var4], none]\")],\ntype_vars: []\n}\n",
     "Function {\nname: \"A.__init__\",\nsig: \"fn[[], none]\",\nvar_id: []\n}\n",
     "Function {\nname: \"A.fun\",\nsig: \"fn[[b=B], none]\",\nvar_id: []\n}\n",
-    "Function {\nname: \"A.foo\",\nsig: \"fn[[a=var3, b=var4], none]\",\nvar_id: [3, 4]\n}\n",
+    "Function {\nname: \"A.foo\",\nsig: \"fn[[a=var3, b=var4], none]\",\nvar_id: [4]\n}\n",
     "Class {\nname: \"B\",\nancestors: [\"{class: B, params: []}\", \"{class: C, params: []}\", \"{class: A, params: []}\"],\nfields: [\"a\"],\nmethods: [(\"__init__\", \"fn[[], none]\"), (\"fun\", \"fn[[b=B], none]\"), (\"foo\", \"fn[[a=var3, b=var4], none]\")],\ntype_vars: []\n}\n",
     "Function {\nname: \"B.__init__\",\nsig: \"fn[[], none]\",\nvar_id: []\n}\n",
     "Class {\nname: \"C\",\nancestors: [\"{class: C, params: []}\", \"{class: A, params: []}\"],\nfields: [\"a\"],\nmethods: [(\"__init__\", \"fn[[], none]\"), (\"fun\", \"fn[[b=B], none]\"), (\"foo\", \"fn[[a=var3, b=var4], none]\")],\ntype_vars: []\n}\n",
     "Function {\nname: \"C.__init__\",\nsig: \"fn[[], none]\",\nvar_id: []\n}\n",
     "Function {\nname: \"C.fun\",\nsig: \"fn[[b=B], none]\",\nvar_id: []\n}\n",
     "Function {\nname: \"foo\",\nsig: \"fn[[a=A], none]\",\nvar_id: []\n}\n",
-    "Function {\nname: \"ff\",\nsig: \"fn[[a=var3], var4]\",\nvar_id: [3, 4]\n}\n",
+    "Function {\nname: \"ff\",\nsig: \"fn[[a=var3], var4]\",\nvar_id: [4]\n}\n",
 ]

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,

nac3core/src/toplevel/type_annotation.rs

@@ -280,9 +280,11 @@ pub fn get_type_from_type_annotation_kinds(
                             {
                                 let ok: bool = {
                                     // create a temp type var and unify to check compatibility
+                                    p == *tvar || {
                                         let temp =
                                             unifier.get_fresh_var_with_range(range.borrow().as_slice());
                                         unifier.unify(temp.0, p).is_ok()
+                                    }
                                 };
                                 if ok {
                                     result.insert(*id, p);

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,

nac3core/src/typecheck/typedef/mod.rs

@@ -719,22 +719,19 @@ impl Unifier {
     /// Returns Some(T) where T is the instantiated type.
     /// Returns None if the function is already instantiated.
     fn instantiate_fun(&mut self, ty: Type, fun: &FunSignature) -> Type {
-        let mut instantiated = false;
+        let mut instantiated = true;
         let mut vars = Vec::new();
         for (k, v) in fun.vars.iter() {
             if let TypeEnum::TVar { id, range, .. } =
                 self.unification_table.probe_value(*v).as_ref()
             {
-                if k != id {
+                // for class methods that contain type vars not in class declaration,
-                    instantiated = true;
+                // as long as there exits one uninstantiated type var, the function is not instantiated,
-                    break;
+                // and need to do substitution on those type vars
-                }
+                if k == id {
-                // actually, if the first check succeeded, the function should be uninstatiated.
+                    instantiated = false;
-                // The cloned values must be used and would not be wasted.
                     vars.push((*k, range.clone()));
-            } else {
+                }
-                instantiated = true;
-                break;
             }
         }
         if instantiated {

nac3standalone/src/basic_symbol_resolver.rs

@@ -1,14 +1,14 @@
 use nac3core::{
     codegen::CodeGenContext,
     location::Location,
-    symbol_resolver::{SymbolResolver, ValueEnum},
+    symbol_resolver::{SymbolResolver, SymbolValue, ValueEnum},
     toplevel::{DefinitionId, TopLevelDef},
     typecheck::{
         type_inferencer::PrimitiveStore,
         typedef::{Type, Unifier},
     },
 };
-use nac3parser::ast::StrRef;
+use nac3parser::ast::{self, StrRef};
 use parking_lot::{Mutex, RwLock};
 use std::{collections::HashMap, sync::Arc};
 
@@ -16,6 +16,7 @@ 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, SymbolValue>>,
 }
 
 impl ResolverInternal {
@@ -26,11 +27,24 @@ 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, val: SymbolValue) {
+        self.module_globals.lock().insert(id, val);
+    }
 }
 
 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, .. } => {
+                self.0.module_globals.lock().get(id).cloned()
+            }
+            _ => unimplemented!("other type of expr not supported at {}", expr.location)
+        }
+    }
+
     fn get_symbol_type(
         &self,
         _: &mut Unifier,

nac3standalone/src/main.rs

@@ -4,8 +4,8 @@ use inkwell::{
     OptimizationLevel,
 };
 use nac3core::typecheck::type_inferencer::PrimitiveStore;
-use nac3parser::parser;
+use nac3parser::{ast::{Expr, ExprKind, StmtKind}, parser};
-use std::env;
+use std::{borrow::Borrow, env};
 use std::fs;
 use std::{collections::HashMap, path::Path, sync::Arc, time::SystemTime};
 
@@ -15,7 +15,7 @@ use nac3core::{
         WorkerRegistry,
     },
     symbol_resolver::SymbolResolver,
-    toplevel::{composer::TopLevelComposer, TopLevelDef},
+    toplevel::{composer::TopLevelComposer, TopLevelDef, helper::parse_parameter_default_value},
     typecheck::typedef::FunSignature,
 };
 
@@ -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 +67,61 @@ fn main() {
     );
 
     for stmt in parser_result.into_iter() {
+        if let StmtKind::Assign { targets, value, .. } = &stmt.node {
+            fn handle_assignment_pattern(
+                targets: &[Expr],
+                value: &Expr,
+                resolver: &(dyn SymbolResolver + Send + Sync),
+                internal_resolver: &ResolverInternal,
+            ) -> Result<(), String> {
+                if targets.len() == 1 {
+                    match &targets[0].node {
+                        ExprKind::Name { id, .. } => {
+                            let val = parse_parameter_default_value(value.borrow(), resolver)?;
+                            internal_resolver.add_module_global(*id, val);
+                            Ok(())
+                        }
+                        ExprKind::List { elts, .. }
+                        | ExprKind::Tuple { elts, .. } => {
+                            handle_assignment_pattern(elts, value, resolver, internal_resolver)?;
+                            Ok(())
+                        }
+                        _ => unreachable!("cannot be assigned")
+                    }
+                } else {
+                    match &value.node {
+                        ExprKind::List { elts, .. }
+                        | ExprKind::Tuple { elts, .. } => {
+                            if elts.len() != targets.len() {
+                                Err(format!(
+                                    "number of elements to unpack does not match (expect {}, found {}) at {}",
+                                    targets.len(),
+                                    elts.len(),
+                                    value.location
+                                ))
+                            } else {
+                                for (tar, val) in targets.iter().zip(elts) {
+                                    handle_assignment_pattern(
+                                        std::slice::from_ref(tar),
+                                        val,
+                                        resolver,
+                                        internal_resolver
+                                    )?;
+                                }
+                                Ok(())
+                            }
+                        },
+                        _ => Err(format!("unpack of this expression is not supported at {}", value.location))
+                    }
+                }
+            }
+            if let Err(err) = handle_assignment_pattern(targets, value, resolver.as_ref(), internal_resolver.as_ref()) {
+                eprintln!("{}", err);
+                return;
+            }
+            continue;
+        }
+
         let (name, def_id, ty) = composer
             .register_top_level(stmt, Some(resolver.clone()), "__main__".into())
             .unwrap();
@@ -100,7 +156,11 @@ fn main() {
 
     let instance = {
         let defs = top_level.definitions.read();
-        let mut instance = defs[resolver.get_identifier_def("run".into()).unwrap().0].write();
+        let mut instance =
+            defs[resolver
+                .get_identifier_def("run".into())
+                .unwrap_or_else(|| panic!("cannot find run() entry point")).0
+            ].write();
         if let TopLevelDef::Function {
             instance_to_stmt,
             instance_to_symbol,