Separate assign_expression method

schala-lang/language/src/eval.rs

@@ -191,23 +191,7 @@ impl<'a> State<'a> {
           Ok(Node::PrimTuple { items: nodes })
         },
         Conditional { box cond, then_clause, else_clause } => self.conditional(cond, then_clause, else_clause),
-        Assign { box val, box expr } => {
+        Assign { box val, box expr } => self.assign_expression(val, expr),
-          let name = match val  {
-            Expr::Val(name) => name,
-            _ => return Err(format!("Trying to assign to a non-value")),
-          };
-
-          let constant = match self.values.lookup(&name) {
-            None => return Err(format!("{} is undefined", name)),
-            Some(ValueEntry::Binding { constant, .. }) => constant.clone(),
-          };
-          if constant {
-            return Err(format!("trying to update {}, a non-mutable binding", name));
-          }
-          let val = self.expression(Node::Expr(expr))?;
-          self.values.insert(name.clone(), ValueEntry::Binding { constant: false, val });
-          Ok(Node::Expr(Expr::Unit))
-        },
         Unit => Ok(Node::Expr(Unit)),
         CaseMatch { box cond, alternatives } => match self.expression(Node::Expr(cond))? {
           Node::PrimObject { name, tag, items } => {
@@ -391,6 +375,24 @@ impl<'a> State<'a> {
     })
   }
 
+  fn assign_expression(&mut self, val: Expr, expr: Expr) -> EvalResult<Node> {
+    let name = match val  {
+      Expr::Val(name) => name,
+      _ => return Err(format!("Trying to assign to a non-value")),
+    };
+
+    let constant = match self.values.lookup(&name) {
+      None => return Err(format!("Constant {} is undefined", name)),
+      Some(ValueEntry::Binding { constant, .. }) => constant.clone(),
+    };
+    if constant {
+      return Err(format!("trying to update {}, a non-mutable binding", name));
+    }
+    let val = self.expression(Node::Expr(expr))?;
+    self.values.insert(name.clone(), ValueEntry::Binding { constant: false, val });
+    Ok(Node::Expr(Expr::Unit))
+  }
+
   fn value(&mut self, name: Rc<String>) -> EvalResult<Node> {
     use self::ValueEntry::*;
     use self::Func::*;