diff --git a/dust-lang/src/abstract_tree/as.rs b/dust-lang/src/abstract_tree/as.rs
index 7db6383..b6da716 100644
--- a/dust-lang/src/abstract_tree/as.rs
+++ b/dust-lang/src/abstract_tree/as.rs
@@ -1,12 +1,38 @@
-use super::{Expression, Type};
+use super::{AbstractNode, Expression, Type, WithPosition};
 
+#[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
 pub struct As {
     expression: Expression,
-    r#type: Type,
+    r#type: WithPosition<Type>,
 }
 
 impl As {
-    pub fn new(expression: Expression, r#type: Type) -> Self {
+    pub fn new(expression: Expression, r#type: WithPosition<Type>) -> Self {
         Self { expression, r#type }
     }
 }
+
+impl AbstractNode for As {
+    fn expected_type(
+        &self,
+        context: &mut crate::context::Context,
+    ) -> Result<Type, crate::error::ValidationError> {
+        todo!()
+    }
+
+    fn validate(
+        &self,
+        context: &mut crate::context::Context,
+        manage_memory: bool,
+    ) -> Result<(), crate::error::ValidationError> {
+        todo!()
+    }
+
+    fn run(
+        self,
+        context: &mut crate::context::Context,
+        manage_memory: bool,
+    ) -> Result<super::Action, crate::error::RuntimeError> {
+        todo!()
+    }
+}
diff --git a/dust-lang/src/abstract_tree/expression.rs b/dust-lang/src/abstract_tree/expression.rs
index f00b44d..e862d59 100644
--- a/dust-lang/src/abstract_tree/expression.rs
+++ b/dust-lang/src/abstract_tree/expression.rs
@@ -41,6 +41,7 @@ impl Expression {
 impl AbstractNode for Expression {
     fn expected_type(&self, _context: &mut Context) -> Result<Type, ValidationError> {
         match self {
+            Expression::As(r#as) => r#as.item.expected_type(_context),
             Expression::FunctionCall(function_call) => function_call.item.expected_type(_context),
             Expression::Identifier(identifier) => {
                 if let Some(r#type) = _context.get_type(&identifier.item)? {
@@ -60,12 +61,12 @@ impl AbstractNode for Expression {
             Expression::BuiltInFunctionCall(built_in_function_call) => {
                 built_in_function_call.item.expected_type(_context)
             }
-            Expression::As(_) => todo!(),
         }
     }
 
     fn validate(&self, context: &mut Context, manage_memory: bool) -> Result<(), ValidationError> {
         match self {
+            Expression::As(r#as) => r#as.item.validate(context, manage_memory),
             Expression::FunctionCall(function_call) => {
                 function_call.item.validate(context, manage_memory)
             }
@@ -98,6 +99,7 @@ impl AbstractNode for Expression {
 
     fn run(self, context: &mut Context, manage_memory: bool) -> Result<Action, RuntimeError> {
         match self {
+            Expression::As(r#as) => r#as.item.run(context, manage_memory),
             Expression::FunctionCall(function_call) => {
                 function_call.item.run(context, manage_memory)
             }
diff --git a/dust-lang/src/lexer.rs b/dust-lang/src/lexer.rs
index 0812cbe..446546e 100644
--- a/dust-lang/src/lexer.rs
+++ b/dust-lang/src/lexer.rs
@@ -258,8 +258,8 @@ pub fn lexer<'src>() -> impl Parser<
 
     let identifier_and_keyword = text::ident().map(|text: &str| match text {
         "any" => Token::Keyword(Keyword::Any),
-        "as" => Token::Keyword(Keyword::As),
         "async" => Token::Keyword(Keyword::Async),
+        "as" => Token::Keyword(Keyword::As),
         "bool" => Token::Keyword(Keyword::Bool),
         "break" => Token::Keyword(Keyword::Break),
         "else" => Token::Keyword(Keyword::Else),
diff --git a/dust-lang/src/parser.rs b/dust-lang/src/parser.rs
index 48c2c3e..cffb0ec 100644
--- a/dust-lang/src/parser.rs
+++ b/dust-lang/src/parser.rs
@@ -335,12 +335,6 @@ pub fn parser<'src>(
                     just(Token::Control(Control::DoubleColon)),
                 );
 
-            let r#as = expression
-                .clone()
-                .then_ignore(just(Token::Keyword(Keyword::As)))
-                .then(r#type.clone())
-                .map_with(|(expression, r#type), state| todo!());
-
             let atom = choice((
                 range.clone(),
                 parsed_function.clone(),
@@ -511,9 +505,20 @@ pub fn parser<'src>(
                 ),
             ));
 
+            let r#as = choice((
+                basic_value.clone(),
+                identifier_expression.clone(),
+                logic_math_indexes_and_function_calls.clone(),
+            ))
+            .then_ignore(just(Token::Keyword(Keyword::As)))
+            .then(r#type.clone())
+            .map_with(|(expression, r#type), state| {
+                Expression::As(Box::new(As::new(expression, r#type)).with_position(state.span()))
+            });
+
             choice((
-                logic_math_indexes_and_function_calls,
                 r#as,
+                logic_math_indexes_and_function_calls,
                 built_in_function_call,
                 range,
                 structure_instance,
@@ -630,6 +635,20 @@ mod tests {
 
     use super::*;
 
+    #[test]
+    fn r#as() {
+        assert_eq!(
+            parse(&lex("1 as str").unwrap()).unwrap()[0],
+            Statement::Expression(Expression::As(
+                Box::new(As::new(
+                    Expression::Value(ValueNode::Integer(1).with_position((0, 1))),
+                    Type::String.with_position((5, 8))
+                ))
+                .with_position((0, 8))
+            ))
+        )
+    }
+
     #[test]
     fn built_in_function() {
         let tokens = lex("READ_LINE").unwrap();