Define some newtypes for Expr

Closes #50

1 files changed, 35 insertions, 0 deletions

diff --git a/dhall/src/expr.rs b/dhall/src/expr.rs
new file mode 100644
index 0000000..0d093cb
--- /dev/null
+++ b/dhall/src/expr.rs
@@ -0,0 +1,35 @@
+use crate::typecheck::TypeError;
+use dhall_core::*;
+
+pub struct Parsed(SubExpr<X, Import>);
+pub struct Resolved(SubExpr<X, X>);
+pub struct Typed(SubExpr<X, X>, Type);
+pub struct Type(Box<Normalized>);
+pub struct Normalized(SubExpr<X, X>);
+
+// impl Parsed {
+//     pub fn resolve(self) -> Result<Resolved, ImportError> {
+//         Ok(Resolved(crate::imports::resolve(self.0)?))
+//     }
+// }
+impl Resolved {
+    pub fn typecheck(self) -> Result<Typed, TypeError<X>> {
+        let typ = Type(Box::new(Normalized(crate::typecheck::type_of(
+            self.0.clone(),
+        )?)));
+        Ok(Typed(self.0, typ))
+    }
+}
+impl Typed {
+    pub fn normalize(self) -> Normalized {
+        Normalized(crate::normalize::normalize(self.0))
+    }
+    pub fn get_type(&self) -> &Type {
+        &self.1
+    }
+}
+impl Type {
+    pub fn as_expr(&self) -> &Normalized {
+        &*self.0
+    }
+}