Add new Value type in API

4 files changed, 86 insertions, 33 deletions

diff --git a/dhall/src/lib.rs b/dhall/src/lib.rs
index 25196ba..60b7a0e 100644
--- a/dhall/src/lib.rs
+++ b/dhall/src/lib.rs
@@ -49,11 +49,18 @@ pub struct Typed {
 }
 
 /// A normalized expression.
-///
-/// Invariant: the contained expression must be in normal form,
 #[derive(Debug, Clone)]
 pub struct Normalized(Nir);
 
+/// A Dhall value.
+#[derive(Debug, Clone)]
+pub struct Value {
+    /// Invariant: in normal form
+    pub(crate) hir: Hir,
+    simple_val: Option<SimpleValue>,
+    simple_ty: Option<SimpleType>,
+}
+
 /// Controls conversion from `Nir` to `Expr`
 #[derive(Copy, Clone, Default)]
 pub(crate) struct ToExprOptions {
@@ -99,8 +106,8 @@ impl Resolved {
     pub fn typecheck(&self) -> Result<Typed, TypeError> {
         Ok(Typed::from_tir(typecheck(&self.0)?))
     }
-    pub fn typecheck_with(self, ty: &Normalized) -> Result<Typed, TypeError> {
-        Ok(Typed::from_tir(typecheck_with(&self.0, ty.to_hir())?))
+    pub(crate) fn typecheck_with(self, ty: &Hir) -> Result<Typed, TypeError> {
+        Ok(Typed::from_tir(typecheck_with(&self.0, ty)?))
     }
     /// Converts a value back to the corresponding AST expression.
     pub fn to_expr(&self) -> ResolvedExpr {
@@ -137,6 +144,13 @@ impl Normalized {
     pub fn encode(&self) -> Result<Vec<u8>, EncodeError> {
         binary::encode(&self.to_expr())
     }
+    pub fn to_value(&self) -> Value {
+        Value {
+            hir: self.to_hir(),
+            simple_val: self.0.to_simple_value(),
+            simple_ty: self.0.to_simple_type(),
+        }
+    }
 
     /// Converts a value back to the corresponding AST expression.
     pub fn to_expr(&self) -> NormalizedExpr {
@@ -200,6 +214,36 @@ impl Normalized {
     }
 }
 
+impl Value {
+    /// Parse a string into a Value, and optionally ensure that the value matches the provided type
+    /// annotation.
+    pub fn from_str_with_annot(
+        s: &str,
+        ty: Option<&Self>,
+    ) -> Result<Self, Error> {
+        let resolved = Parsed::parse_str(s)?.resolve()?;
+        let typed = match ty {
+            None => resolved.typecheck()?,
+            Some(ty) => resolved.typecheck_with(&ty.hir)?,
+        };
+        Ok(typed.normalize().to_value())
+    }
+
+    /// Converts a Value into a SimpleValue.
+    pub fn to_simple_value(&self) -> Option<SimpleValue> {
+        self.simple_val.clone()
+    }
+    /// Converts a Value into a SimpleType.
+    pub fn to_simple_type(&self) -> Option<SimpleType> {
+        self.simple_ty.clone()
+    }
+
+    /// Converts a value back to the corresponding AST expression.
+    pub(crate) fn to_expr(&self) -> NormalizedExpr {
+        self.hir.to_expr(ToExprOptions::default())
+    }
+}
+
 macro_rules! derive_traits_for_wrapper_struct {
     ($ty:ident) => {
         impl std::cmp::PartialEq for $ty {
@@ -274,3 +318,15 @@ impl Display for Normalized {
         self.to_expr().fmt(f)
     }
 }
+
+impl Eq for Value {}
+impl PartialEq for Value {
+    fn eq(&self, other: &Self) -> bool {
+        self.hir == other.hir
+    }
+}
+impl Display for Value {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
+        self.to_expr().fmt(f)
+    }
+}
diff --git a/dhall/src/semantics/tck/typecheck.rs b/dhall/src/semantics/tck/typecheck.rs
index 173b76d..9fa33f2 100644
--- a/dhall/src/semantics/tck/typecheck.rs
+++ b/dhall/src/semantics/tck/typecheck.rs
@@ -808,8 +808,8 @@ pub(crate) fn typecheck<'hir>(hir: &'hir Hir) -> Result<Tir<'hir>, TypeError> {
 /// Like `typecheck`, but additionally checks that the expression's type matches the provided type.
 pub(crate) fn typecheck_with<'hir>(
     hir: &'hir Hir,
-    ty: Hir,
+    ty: &Hir,
 ) -> Result<Tir<'hir>, TypeError> {
-    let ty = typecheck(&ty)?.eval_to_type(&TyEnv::new())?;
+    let ty = typecheck(ty)?.eval_to_type(&TyEnv::new())?;
     type_with(&TyEnv::new(), hir, Some(ty))
 }
diff --git a/serde_dhall/src/lib.rs b/serde_dhall/src/lib.rs
index d019238..1f7ecf8 100644
--- a/serde_dhall/src/lib.rs
+++ b/serde_dhall/src/lib.rs
@@ -183,38 +183,26 @@ pub use value::Value;
 // A Dhall value.
 #[doc(hidden)]
 pub mod value {
-    use dhall::{Normalized, NormalizedExpr, Parsed, SimpleType, SimpleValue};
+    use dhall::{SimpleType, SimpleValue};
 
     use super::de::Error;
     use super::Type;
 
     /// A Dhall value
     #[derive(Debug, Clone, PartialEq, Eq)]
-    pub struct Value(pub(crate) Normalized);
+    pub struct Value(pub(crate) dhall::Value);
 
     impl Value {
         pub fn from_str(s: &str, ty: Option<&Type>) -> super::de::Result<Self> {
-            Value::from_str_using_dhall_error_type(s, ty).map_err(Error::Dhall)
+            let ty = ty.map(|t| t.to_dhall_value());
+            let val = dhall::Value::from_str_with_annot(s, ty.as_ref())
+                .map_err(Error::Dhall)?;
+            Ok(Value(val))
         }
-        fn from_str_using_dhall_error_type(
-            s: &str,
-            ty: Option<&Type>,
-        ) -> dhall::error::Result<Self> {
-            let resolved = Parsed::parse_str(s)?.resolve()?;
-            let typed = match ty {
-                None => resolved.typecheck()?,
-                Some(t) => resolved.typecheck_with(&t.to_normalized())?,
-            };
-            Ok(Value(typed.normalize()))
-        }
-        pub(crate) fn to_simple_value(
-            &self,
-        ) -> Result<SimpleValue, NormalizedExpr> {
+        pub(crate) fn to_simple_value(&self) -> Option<SimpleValue> {
             self.0.to_simple_value()
         }
-        pub(crate) fn to_simple_type(
-            &self,
-        ) -> Result<SimpleType, NormalizedExpr> {
+        pub(crate) fn to_simple_type(&self) -> Option<SimpleType> {
             self.0.to_simple_type()
         }
     }
@@ -226,12 +214,21 @@ pub mod value {
             Ok(v.clone())
         }
     }
+
+    impl std::fmt::Display for Value {
+        fn fmt(
+            &self,
+            f: &mut std::fmt::Formatter,
+        ) -> Result<(), std::fmt::Error> {
+            self.0.fmt(f)
+        }
+    }
 }
 
 // A Dhall type.
 #[doc(hidden)]
 pub mod ty {
-    use dhall::{Normalized, STyKind, SimpleType};
+    use dhall::{STyKind, SimpleType};
 
     use super::de::Error;
 
@@ -240,8 +237,8 @@ pub mod ty {
     pub struct Type(SimpleType);
 
     impl Type {
-        pub(crate) fn to_normalized(&self) -> Normalized {
-            self.0.clone().into_normalized()
+        pub(crate) fn to_dhall_value(&self) -> dhall::Value {
+            self.0.clone().into_normalized().to_value()
         }
 
         pub(crate) fn from_simple_type(ty: SimpleType) -> Self {
@@ -279,10 +276,10 @@ pub mod ty {
 
     impl super::de::Deserialize for Type {
         fn from_dhall(v: &super::Value) -> super::de::Result<Self> {
-            let sty = v.to_simple_type().map_err(|expr| {
+            let sty = v.to_simple_type().ok_or_else(|| {
                 Error::Deserialize(format!(
                     "this cannot be deserialized into a simple type: {}",
-                    expr
+                    v
                 ))
             })?;
             Ok(Type(sty))
diff --git a/serde_dhall/src/serde.rs b/serde_dhall/src/serde.rs
index 9cb67d1..5d8fcf3 100644
--- a/serde_dhall/src/serde.rs
+++ b/serde_dhall/src/serde.rs
@@ -19,10 +19,10 @@ where
     T: serde::Deserialize<'a>,
 {
     fn from_dhall(v: &Value) -> Result<Self> {
-        let sval = v.to_simple_value().map_err(|expr| {
+        let sval = v.to_simple_value().ok_or_else(|| {
             Error::Deserialize(format!(
                 "this cannot be deserialized into the serde data model: {}",
-                expr
+                v
             ))
         })?;
         T::deserialize(Deserializer(Cow::Owned(sval)))