diff --git a/src/core/InputInterpreter.cs b/src/core/InputInterpreter.cs
index bd409a4..d631ccf 100644
--- a/src/core/InputInterpreter.cs
+++ b/src/core/InputInterpreter.cs
@@ -26,10 +26,10 @@ namespace csmic
 
         public InputInterpreter()
         {
-            numericVariables = new(StringComparer.Ordinal);
-            numericArrayVariables = new(StringComparer.Ordinal);
-            expressionVariables = new(StringComparer.Ordinal);
-            functions = new(StringComparer.Ordinal);
+            numericVariables = new Dictionary<string, decimal>(StringComparer.Ordinal);
+            numericArrayVariables = new Dictionary<string, decimal[]>(StringComparer.Ordinal);
+            expressionVariables = new Dictionary<string, string>(StringComparer.Ordinal);
+            functions = new Dictionary<string, ICodedFunction>(StringComparer.Ordinal);
         }
 
         // Internal constructor to create a child interpreter that shares stores
diff --git a/src/core/cocor/Interpreter.atg b/src/core/cocor/Interpreter.atg
index 5d19d0d..d8c437b 100644
--- a/src/core/cocor/Interpreter.atg
+++ b/src/core/cocor/Interpreter.atg
@@ -307,7 +307,7 @@ Function<out FunctionValue r>
 .
 
 ArgList<out FunctionArgument[] args>
-    (. List<FunctionArgument> list = new List<FunctionArgument>(); FunctionArgument a = new FunctionArgument { Name = string.Empty, Value = new FunctionValue() }; args = new FunctionArgument[0]; .)
+    (. List<FunctionArgument> list = new List<FunctionArgument>(); FunctionArgument a = new FunctionArgument(string.Empty, new FunctionValue()); args = new FunctionArgument[0]; .)
 =
     [
         Arg<out a> (. list.Add(a); args = list.ToArray(); .)
@@ -316,12 +316,12 @@ ArgList<out FunctionArgument[] args>
 .
 
 Arg<out FunctionArgument arg>
-    (. arg = new FunctionArgument { Name = string.Empty, Value = new FunctionValue() }; decimal r = 0; string s = string.Empty; .)
+    (. arg = new FunctionArgument(string.Empty, new FunctionValue()); decimal r = 0; string s = string.Empty; .)
 =
     (
-        string (. s = t.val.Substring(1, t.val.Length - 2); arg = new FunctionArgument { Name = string.Empty, Value = new FunctionValue(ValueType.String, s) }; .)
+        string (. s = t.val.Substring(1, t.val.Length - 2); arg = new FunctionArgument(string.Empty, new FunctionValue(ValueType.String, s)); .)
       |
-        Expression<out r> (. arg = new FunctionArgument { Name = string.Empty, Value = new FunctionValue(ValueType.Numeric, r) }; .)
+        Expression<out r> (. arg = new FunctionArgument(string.Empty, new FunctionValue(ValueType.Numeric, r)); .)
     )
 .