diff --git a/schala-lang/src/ast_reducing.rs b/schala-lang/src/ast_reducing.rs
index fd660f5..3555907 100644
--- a/schala-lang/src/ast_reducing.rs
+++ b/schala-lang/src/ast_reducing.rs
@@ -10,6 +10,7 @@ pub struct ReducedAST(pub Vec<Stmt>);
 pub enum Stmt {
   Binding {
     name: Rc<String>,
+    constant: bool,
     expr: Expr,
   },
   Expr(Expr),
@@ -76,7 +77,11 @@ impl Expression {
 
 impl Declaration {
   fn reduce(&self) -> Stmt {
-    Stmt::Expr(Expr::UnimplementedSigilValue)
+    use self::Declaration::*;
+    match self {
+      &Binding { ref name, ref constant, ref expr } => Stmt::Binding { name: name.clone(), constant: *constant, expr: expr.reduce() },
+      _ => Stmt::Expr(Expr::UnimplementedSigilValue)
+    }
   }
 }
 
diff --git a/schala-lang/src/eval.rs b/schala-lang/src/eval.rs
index 65452ba..8354cf3 100644
--- a/schala-lang/src/eval.rs
+++ b/schala-lang/src/eval.rs
@@ -19,6 +19,7 @@ impl<'a> State<'a> {
 #[derive(Debug)]
 enum ValueEntry {
   Binding {
+    constant: bool,
     val: /*FullyEvaluatedExpr*/ Expr,
   },
   /*
@@ -364,8 +365,9 @@ impl<'a> State<'a> {
 
   fn statement(&mut self, stmt: Stmt) -> EvalResult<Option<Expr>> {
     match stmt {
-      Stmt::Binding { .. } => {
-        //TODO mutate some state here
+      Stmt::Binding { name, constant, expr } => {
+        let val = self.expression(expr)?;
+        self.values.insert(name.clone(), ValueEntry::Binding { constant, val });
         Ok(None)
       },
       Stmt::Expr(expr) => Ok(Some(self.expression(expr)?)),