Derive DhallType for structs

2 files changed, 79 insertions, 0 deletions

diff --git a/dhall/src/dhall_type.rs b/dhall/src/dhall_type.rs
new file mode 100644
index 0000000..8abef32
--- /dev/null
+++ b/dhall/src/dhall_type.rs
@@ -0,0 +1,77 @@
+use dhall_core::*;
+use dhall_generator::*;
+
+#[derive(Debug, Clone)]
+pub enum DhallConversionError {}
+
+pub trait DhallType: Sized {
+    fn dhall_type() -> DhallExpr;
+    // fn as_dhall(&self) -> DhallExpr;
+    // fn from_dhall(e: DhallExpr) -> Result<Self, DhallConversionError>;
+}
+
+impl DhallType for bool {
+    fn dhall_type() -> DhallExpr {
+        dhall_expr!(Bool)
+    }
+}
+
+impl DhallType for Natural {
+    fn dhall_type() -> DhallExpr {
+        dhall_expr!(Natural)
+    }
+}
+
+impl DhallType for Integer {
+    fn dhall_type() -> DhallExpr {
+        dhall_expr!(Integer)
+    }
+}
+
+impl DhallType for String {
+    fn dhall_type() -> DhallExpr {
+        dhall_expr!(Text)
+    }
+}
+
+impl<A: DhallType, B: DhallType> DhallType for (A, B) {
+    fn dhall_type() -> DhallExpr {
+        let ta = A::dhall_type();
+        let tb = B::dhall_type();
+        dhall_expr!({ _1: ta, _2: tb })
+    }
+}
+
+impl<T: DhallType> DhallType for Option<T> {
+    fn dhall_type() -> DhallExpr {
+        let t = T::dhall_type();
+        dhall_expr!(Optional t)
+    }
+}
+
+impl<T: DhallType> DhallType for Vec<T> {
+    fn dhall_type() -> DhallExpr {
+        let t = T::dhall_type();
+        dhall_expr!(List t)
+    }
+}
+
+impl<'a, T: DhallType> DhallType for &'a T {
+    fn dhall_type() -> DhallExpr {
+        T::dhall_type()
+    }
+}
+
+impl<T> DhallType for std::marker::PhantomData<T> {
+    fn dhall_type() -> DhallExpr {
+        dhall_expr!({})
+    }
+}
+
+impl<T: DhallType, E: DhallType> DhallType for Result<T, E> {
+    fn dhall_type() -> DhallExpr {
+        let tt = T::dhall_type();
+        let te = E::dhall_type();
+        dhall_expr!(< Ok: tt | Err: te>)
+    }
+}
diff --git a/dhall/src/lib.rs b/dhall/src/lib.rs
index d9f9edb..c0c1d6f 100644
--- a/dhall/src/lib.rs
+++ b/dhall/src/lib.rs
@@ -10,8 +10,10 @@
 mod normalize;
 pub use crate::normalize::*;
 pub mod binary;
+mod dhall_type;
 pub mod imports;
 pub mod typecheck;
+pub use dhall_type::*;
 
 pub use crate::imports::*;