diff --git a/evaluator.py b/evaluator.py
index 269dc06..c1b258b 100644
--- a/evaluator.py
+++ b/evaluator.py
@@ -1,5 +1,5 @@
 from typing import Dict, List, Optional, cast
-from position import Node
+from position import Node, Span
 from utils import Err, Ok, Result
 import parsed
 
@@ -30,6 +30,9 @@ class Bool(Value):
         super().__init__()
         self.value = value
 
+class Type:
+    pass
+
 class EvalResult:
     pass
 
@@ -60,16 +63,36 @@ class PanicResult(EvalResult):
 
 class SymbolTable:
     def __init__(self) -> None:
-        self.symbols: Dict[str, Value] = {}
+        self.values: Dict[str, Value] = {}
+        self.types: Dict[str, Type] = {}
 
-    def define(self, symbol_id: str, value: Value) -> Result[None, str]:
-        if symbol_id in self.symbols:
+    def define_value(self, symbol_id: str, value: Value) -> Result[None, str]:
+        if symbol_id in self.values:
             return Err("symbol already defined")
+        self.values[symbol_id] = value
         return Ok(None)
 
+    def define_type(self, symbol_id: str, value_type: Type) -> Result[None, str]:
+        if symbol_id in self.types:
+            return Err("symbol already defined")
+        self.types[symbol_id] = value_type
+        return Ok(None)
+
+    def value(self, symbol_id: str) -> Optional[Value]:
+        if symbol_id not in self.values:
+            return None
+        else:
+            return self.values[symbol_id]
+
+    def type(self, symbol_id: str) -> Optional[Type]:
+        if symbol_id not in self.types:
+            return None
+        else:
+            return self.types[symbol_id]
+
 class Evaluator:
     def __init__(self) -> None:
-        pass
+        self.table = SymbolTable()
 
     def evaluate(self, ast: List[Node[parsed.Expr]]) -> None:
         for node in ast:
@@ -77,59 +100,140 @@ class Evaluator:
 
     def eval_expr(self, node: Node[parsed.Expr]) -> EvalResult:
         if isinstance(node.value, parsed.ExprError):
-            return PanicResult(f"error: {cast(parsed.ExprError, node.value).message}, at {node.span}")
+            return self.eval_expr_error(cast(parsed.ExprError, node.value), node.span)
         elif isinstance(node.value, parsed.Id):
-            raise NotImplementedError()
+            return self.eval_id(cast(parsed.Id, node.value), node.span)
         elif isinstance(node.value, parsed.Int):
-            return ValueResult(Int(cast(parsed.Int, node.value).value))
+            return self.eval_int(cast(parsed.Int, node.value), node.span)
         elif isinstance(node.value, parsed.Char):
-            return ValueResult(Char(cast(parsed.Char, node.value).value))
+            return self.eval_char(cast(parsed.Char, node.value), node.span)
         elif isinstance(node.value, parsed.String):
-            return ValueResult(String(cast(parsed.String, node.value).value))
+            return self.eval_string(cast(parsed.String, node.value), node.span)
         elif isinstance(node.value, parsed.Bool):
-            return ValueResult(Bool(cast(parsed.Bool, node.value).value))
+            return self.eval_bool(cast(parsed.Bool, node.value), node.span)
         elif isinstance(node.value, parsed.Unit):
-            return ValueResult(Unit())
+            return self.eval_unit(cast(parsed.Unit, node.value), node.span)
         elif isinstance(node.value, parsed.Tuple):
-            raise NotImplementedError()
+            return self.eval_tuple(cast(parsed.Tuple, node.value), node.span)
         elif isinstance(node.value, parsed.Block):
-            raise NotImplementedError()
+            return self.eval_block(cast(parsed.Block, node.value), node.span)
         elif isinstance(node.value, parsed.Lambda):
-            raise NotImplementedError()
+            return self.eval_lambda(cast(parsed.Lambda, node.value), node.span)
         elif isinstance(node.value, parsed.If):
-            raise NotImplementedError()
+            return self.eval_if(cast(parsed.If, node.value), node.span)
         elif isinstance(node.value, parsed.Match):
-            raise NotImplementedError()
+            return self.eval_match(cast(parsed.Match, node.value), node.span)
         elif isinstance(node.value, parsed.Loop):
-            raise NotImplementedError()
+            return self.eval_loop(cast(parsed.Loop, node.value), node.span)
         elif isinstance(node.value, parsed.While):
-            raise NotImplementedError()
+            return self.eval_while(cast(parsed.While, node.value), node.span)
         elif isinstance(node.value, parsed.For):
-            raise NotImplementedError()
+            return self.eval_for(cast(parsed.For, node.value), node.span)
         elif isinstance(node.value, parsed.StructMember):
-            raise NotImplementedError()
+            return self.eval_struct_member(cast(parsed.StructMember, node.value), node.span)
         elif isinstance(node.value, parsed.TupleMember):
-            raise NotImplementedError()
+            return self.eval_tuple_member(cast(parsed.TupleMember, node.value), node.span)
         elif isinstance(node.value, parsed.Index):
-            raise NotImplementedError()
+            return self.eval_index(cast(parsed.Index, node.value), node.span)
         elif isinstance(node.value, parsed.Call):
-            raise NotImplementedError()
+            return self.eval_call(cast(parsed.Call, node.value), node.span)
         elif isinstance(node.value, parsed.Unary):
-            raise NotImplementedError()
+            return self.eval_unary(cast(parsed.Unary, node.value), node.span)
         elif isinstance(node.value, parsed.Binary):
-            raise NotImplementedError()
+            return self.eval_binary(cast(parsed.Binary, node.value), node.span)
         elif isinstance(node.value, parsed.Assign):
-            raise NotImplementedError()
+            return self.eval_assign(cast(parsed.Assign, node.value), node.span)
         elif isinstance(node.value, parsed.Let):
-            raise NotImplementedError()
+            return self.eval_let(cast(parsed.Let, node.value), node.span)
         elif isinstance(node.value, parsed.Function):
-            raise NotImplementedError()
+            return self.eval_function(cast(parsed.Function, node.value), node.span)
         elif isinstance(node.value, parsed.Return):
-            raise NotImplementedError()
+            return self.eval_return(cast(parsed.Return, node.value), node.span)
         elif isinstance(node.value, parsed.Break):
-            raise NotImplementedError()
+            return self.eval_break(cast(parsed.Break, node.value), node.span)
         elif isinstance(node.value, parsed.Continue):
-            raise NotImplementedError()
+            return self.eval_continue(cast(parsed.Continue, node.value), node.span)
         else:
             raise NotImplementedError(str(node))
 
+    def eval_expr_error(self, expr: parsed.ExprError, span: Span) -> EvalResult:
+        return PanicResult(f"error: {expr.message}, at {span}")
+
+    def eval_id(self, expr: parsed.Id, span: Span) -> EvalResult:
+        raise NotImplementedError()
+
+    def eval_int(self, expr: parsed.Int, span: Span) -> EvalResult:
+        return ValueResult(Int(expr.value))
+
+    def eval_char(self, expr: parsed.Char, span: Span) -> EvalResult:
+        return ValueResult(Char(expr.value))
+
+    def eval_string(self, expr: parsed.String, span: Span) -> EvalResult:
+        return ValueResult(String(expr.value))
+
+    def eval_bool(self, expr: parsed.Bool, span: Span) -> EvalResult:
+        return ValueResult(Bool(expr.value))
+
+    def eval_unit(self, expr: parsed.Unit, span: Span) -> EvalResult:
+        return ValueResult(Unit())
+
+    def eval_tuple(self, expr: parsed.Tuple, span: Span) -> EvalResult:
+        raise NotImplementedError()
+
+    def eval_block(self, expr: parsed.Block, span: Span) -> EvalResult:
+        raise NotImplementedError()
+
+    def eval_lambda(self, expr: parsed.Lambda, span: Span) -> EvalResult:
+        raise NotImplementedError()
+
+    def eval_if(self, expr: parsed.If, span: Span) -> EvalResult:
+        raise NotImplementedError()
+
+    def eval_match(self, expr: parsed.Match, span: Span) -> EvalResult:
+        raise NotImplementedError()
+
+    def eval_loop(self, expr: parsed.Loop, span: Span) -> EvalResult:
+        raise NotImplementedError()
+
+    def eval_while(self, expr: parsed.While, span: Span) -> EvalResult:
+        raise NotImplementedError()
+
+    def eval_for(self, expr: parsed.For, span: Span) -> EvalResult:
+        raise NotImplementedError()
+
+    def eval_struct_member(self, expr: parsed.StructMember, span: Span) -> EvalResult:
+        raise NotImplementedError()
+
+    def eval_tuple_member(self, expr: parsed.TupleMember, span: Span) -> EvalResult:
+        raise NotImplementedError()
+
+    def eval_index(self, expr: parsed.Index, span: Span) -> EvalResult:
+        raise NotImplementedError()
+
+    def eval_call(self, expr: parsed.Call, span: Span) -> EvalResult:
+        raise NotImplementedError()
+
+    def eval_unary(self, expr: parsed.Unary, span: Span) -> EvalResult:
+        raise NotImplementedError()
+
+    def eval_binary(self, expr: parsed.Binary, span: Span) -> EvalResult:
+        raise NotImplementedError()
+
+    def eval_assign(self, expr: parsed.Assign, span: Span) -> EvalResult:
+        raise NotImplementedError()
+
+    def eval_let(self, expr: parsed.Let, span: Span) -> EvalResult:
+        raise NotImplementedError()
+
+    def eval_function(self, expr: parsed.Function, span: Span) -> EvalResult:
+        raise NotImplementedError()
+
+    def eval_return(self, expr: parsed.Return, span: Span) -> EvalResult:
+        raise NotImplementedError()
+
+    def eval_break(self, expr: parsed.Break, span: Span) -> EvalResult:
+        raise NotImplementedError()
+
+    def eval_continue(self, expr: parsed.Continue, span: Span) -> EvalResult:
+        raise NotImplementedError()
+