Merge pull request #95 from Nadrieril/catchup-spec

A lot more catching up on the spec

7 files changed, 254 insertions, 548 deletions

diff --git a/dhall/src/core/value.rs b/dhall/src/core/value.rs
index bc8fa34..d7b9149 100644
--- a/dhall/src/core/value.rs
+++ b/dhall/src/core/value.rs
@@ -47,6 +47,7 @@ pub enum Value {
     DoubleLit(NaiveDouble),
     EmptyOptionalLit(TypeThunk),
     NEOptionalLit(Thunk),
+    // EmptyListLit(t) means `[] : List t`
     EmptyListLit(TypeThunk),
     NEListLit(Vec<Thunk>),
     RecordLit(HashMap<Label, Thunk>),
@@ -128,9 +129,10 @@ impl Value {
             Value::NEOptionalLit(n) => {
                 rc(ExprF::SomeLit(n.normalize_to_expr_maybe_alpha(alpha)))
             }
-            Value::EmptyListLit(n) => {
-                rc(ExprF::EmptyListLit(n.normalize_to_expr_maybe_alpha(alpha)))
-            }
+            Value::EmptyListLit(n) => rc(ExprF::EmptyListLit(rc(ExprF::App(
+                rc(ExprF::Builtin(Builtin::List)),
+                n.normalize_to_expr_maybe_alpha(alpha),
+            )))),
             Value::NEListLit(elts) => rc(ExprF::NEListLit(
                 elts.iter()
                     .map(|n| n.normalize_to_expr_maybe_alpha(alpha))
@@ -176,19 +178,10 @@ impl Value {
                     .collect();
                 rc(ExprF::Field(rc(ExprF::UnionType(kts)), l.clone()))
             }
-            Value::UnionLit(l, v, kts) => rc(ExprF::UnionLit(
-                l.clone(),
+            Value::UnionLit(l, v, kts) => rc(ExprF::App(
+                Value::UnionConstructor(l.clone(), kts.clone())
+                    .normalize_to_expr_maybe_alpha(alpha),
                 v.normalize_to_expr_maybe_alpha(alpha),
-                kts.iter()
-                    .map(|(k, v)| {
-                        (
-                            k.clone(),
-                            v.as_ref().map(|v| {
-                                v.normalize_to_expr_maybe_alpha(alpha)
-                            }),
-                        )
-                    })
-                    .collect(),
             )),
             Value::TextLit(elts) => {
                 use InterpolatedTextContents::{Expr, Text};
diff --git a/dhall/src/error/mod.rs b/dhall/src/error/mod.rs
index aed6ccd..a0ee30a 100644
--- a/dhall/src/error/mod.rs
+++ b/dhall/src/error/mod.rs
@@ -86,7 +86,7 @@ pub(crate) enum TypeMessage {
     RecordTypeMergeRequiresRecordType(Type),
     RecordTypeMismatch(Type, Type, Type, Type),
     UnionTypeDuplicateField,
-    Unimplemented,
+    // Unimplemented,
 }
 
 impl TypeError {
diff --git a/dhall/src/phase/binary.rs b/dhall/src/phase/binary.rs
index 1812131..5e7eb40 100644
--- a/dhall/src/phase/binary.rs
+++ b/dhall/src/phase/binary.rs
@@ -48,10 +48,21 @@ fn cbor_value_to_dhall(
         Bool(b) => BoolLit(*b),
         Array(vec) => match vec.as_slice() {
             [String(l), U64(n)] => {
+                if l.as_str() == "_" {
+                    Err(DecodeError::WrongFormatError(
+                        "`_` variable was encoded incorrectly".to_owned(),
+                    ))?
+                }
                 let l = Label::from(l.as_str());
                 Var(V(l, *n as usize))
             }
             [U64(0), f, args..] => {
+                if args.is_empty() {
+                    Err(DecodeError::WrongFormatError(
+                        "Function application must have at least one argument"
+                            .to_owned(),
+                    ))?
+                }
                 let mut f = cbor_value_to_dhall(&f)?;
                 for a in args {
                     let a = cbor_value_to_dhall(&a)?;
@@ -65,6 +76,11 @@ fn cbor_value_to_dhall(
                 Lam(Label::from("_"), x, y)
             }
             [U64(1), String(l), x, y] => {
+                if l.as_str() == "_" {
+                    Err(DecodeError::WrongFormatError(
+                        "`_` variable was encoded incorrectly".to_owned(),
+                    ))?
+                }
                 let x = cbor_value_to_dhall(&x)?;
                 let y = cbor_value_to_dhall(&y)?;
                 let l = Label::from(l.as_str());
@@ -76,6 +92,11 @@ fn cbor_value_to_dhall(
                 Pi(Label::from("_"), x, y)
             }
             [U64(2), String(l), x, y] => {
+                if l.as_str() == "_" {
+                    Err(DecodeError::WrongFormatError(
+                        "`_` variable was encoded incorrectly".to_owned(),
+                    ))?
+                }
                 let x = cbor_value_to_dhall(&x)?;
                 let y = cbor_value_to_dhall(&y)?;
                 let l = Label::from(l.as_str());
@@ -106,7 +127,7 @@ fn cbor_value_to_dhall(
             }
             [U64(4), t] => {
                 let t = cbor_value_to_dhall(&t)?;
-                EmptyListLit(t)
+                EmptyListLit(rc(App(rc(ExprF::Builtin(Builtin::List)), t)))
             }
             [U64(4), Null, rest..] => {
                 let rest = rest
@@ -115,18 +136,22 @@ fn cbor_value_to_dhall(
                     .collect::<Result<Vec<_>, _>>()?;
                 NEListLit(rest)
             }
-            [U64(5), t] => {
-                let t = cbor_value_to_dhall(&t)?;
-                OldOptionalLit(None, t)
-            }
             [U64(5), Null, x] => {
                 let x = cbor_value_to_dhall(&x)?;
                 SomeLit(x)
             }
+            // Old-style optional literals
+            [U64(5), t] => {
+                let t = cbor_value_to_dhall(&t)?;
+                App(rc(ExprF::Builtin(Builtin::OptionalNone)), t)
+            }
             [U64(5), t, x] => {
                 let x = cbor_value_to_dhall(&x)?;
                 let t = cbor_value_to_dhall(&t)?;
-                OldOptionalLit(Some(x), t)
+                Annot(
+                    rc(SomeLit(x)),
+                    rc(App(rc(ExprF::Builtin(Builtin::Optional)), t)),
+                )
             }
             [U64(6), x, y] => {
                 let x = cbor_value_to_dhall(&x)?;
@@ -156,12 +181,9 @@ fn cbor_value_to_dhall(
                 let map = cbor_map_to_dhall_opt_map(map)?;
                 UnionType(map)
             }
-            [U64(12), String(l), x, Object(map)] => {
-                let map = cbor_map_to_dhall_opt_map(map)?;
-                let x = cbor_value_to_dhall(&x)?;
-                let l = Label::from(l.as_str());
-                UnionLit(l, x, map)
-            }
+            [U64(12), ..] => Err(DecodeError::WrongFormatError(
+                "Union literals are not supported anymore".to_owned(),
+            ))?,
             [U64(14), x, y, z] => {
                 let x = cbor_value_to_dhall(&x)?;
                 let y = cbor_value_to_dhall(&y)?;
@@ -191,8 +213,13 @@ fn cbor_value_to_dhall(
             }
             [U64(24), hash, U64(mode), U64(scheme), rest..] => {
                 let mode = match mode {
+                    0 => ImportMode::Code,
                     1 => ImportMode::RawText,
-                    _ => ImportMode::Code,
+                    2 => ImportMode::Location,
+                    _ => Err(DecodeError::WrongFormatError(format!(
+                        "import/mode/unknown_mode: {:?}",
+                        mode
+                    )))?,
                 };
                 let hash = match hash {
                     Null => None,
@@ -216,18 +243,20 @@ fn cbor_value_to_dhall(
                         };
                         let headers = match rest.next() {
                             Some(Null) => None,
-                            Some(x) => {
-                                match cbor_value_to_dhall(&x)?.as_ref() {
-                                    Embed(import) => Some(Box::new(
-                                        import.location_hashed.clone(),
-                                    )),
-                                    _ => Err(DecodeError::WrongFormatError(
-                                        "import/remote/headers".to_owned(),
-                                    ))?,
-                                }
-                            }
+                            // TODO
+                            // Some(x) => {
+                            //     match cbor_value_to_dhall(&x)?.as_ref() {
+                            //         Embed(import) => Some(Box::new(
+                            //             import.location_hashed.clone(),
+                            //         )),
+                            //         _ => Err(DecodeError::WrongFormatError(
+                            //             "import/remote/headers".to_owned(),
+                            //         ))?,
+                            //     }
+                            // }
                             _ => Err(DecodeError::WrongFormatError(
-                                "import/remote/headers".to_owned(),
+                                "import/remote/headers is unimplemented"
+                                    .to_owned(),
                             ))?,
                         };
                         let authority = match rest.next() {
@@ -330,6 +359,10 @@ fn cbor_value_to_dhall(
                 let y = cbor_value_to_dhall(&y)?;
                 Annot(x, y)
             }
+            [U64(28), x] => {
+                let x = cbor_value_to_dhall(&x)?;
+                EmptyListLit(x)
+            }
             _ => Err(DecodeError::WrongFormatError(format!("{:?}", data)))?,
         },
         _ => Err(DecodeError::WrongFormatError(format!("{:?}", data)))?,
@@ -378,7 +411,6 @@ enum Serialize<'a> {
     CBOR(cbor::Value),
     RecordMap(&'a DupTreeMap<Label, ParsedSubExpr>),
     UnionMap(&'a DupTreeMap<Label, Option<ParsedSubExpr>>),
-    Import(&'a Import),
 }
 
 macro_rules! count {
@@ -403,6 +435,7 @@ where
     S: serde::ser::Serializer,
 {
     use cbor::Value::{String, I64, U64};
+    use dhall_syntax::Builtin;
     use dhall_syntax::ExprF::*;
     use std::iter::once;
 
@@ -444,12 +477,23 @@ where
             ser_seq!(ser; tag(2), expr(x), expr(y))
         }
         Pi(l, x, y) => ser_seq!(ser; tag(2), label(l), expr(x), expr(y)),
-        // TODO: multilet
-        Let(l, None, x, y) => {
-            ser_seq!(ser; tag(25), label(l), null(), expr(x), expr(y))
-        }
-        Let(l, Some(t), x, y) => {
-            ser_seq!(ser; tag(25), label(l), expr(t), expr(x), expr(y))
+        Let(_, _, _, _) => {
+            let (bound_e, bindings) = collect_nested_lets(e);
+            let count = 1 + 3 * bindings.len() + 1;
+
+            use serde::ser::SerializeSeq;
+            let mut ser_seq = ser.serialize_seq(Some(count))?;
+            ser_seq.serialize_element(&tag(25))?;
+            for (l, t, v) in bindings {
+                ser_seq.serialize_element(&label(l))?;
+                match t {
+                    Some(t) => ser_seq.serialize_element(&expr(t))?,
+                    None => ser_seq.serialize_element(&null())?,
+                }
+                ser_seq.serialize_element(&expr(v))?;
+            }
+            ser_seq.serialize_element(&expr(bound_e))?;
+            ser_seq.end()
         }
         App(_, _) => {
             let (f, args) = collect_nested_applications(e);
@@ -460,10 +504,14 @@ where
             )
         }
         Annot(x, y) => ser_seq!(ser; tag(26), expr(x), expr(y)),
-        OldOptionalLit(None, t) => ser_seq!(ser; tag(5), expr(t)),
-        OldOptionalLit(Some(x), t) => ser_seq!(ser; tag(5), expr(t), expr(x)),
         SomeLit(x) => ser_seq!(ser; tag(5), null(), expr(x)),
-        EmptyListLit(x) => ser_seq!(ser; tag(4), expr(x)),
+        EmptyListLit(x) => match x.as_ref() {
+            App(f, a) => match f.as_ref() {
+                ExprF::Builtin(Builtin::List) => ser_seq!(ser; tag(4), expr(a)),
+                _ => ser_seq!(ser; tag(28), expr(x)),
+            },
+            _ => ser_seq!(ser; tag(28), expr(x)),
+        },
         NEListLit(xs) => ser.collect_seq(
             once(tag(4)).chain(once(null())).chain(xs.iter().map(expr)),
         ),
@@ -477,9 +525,6 @@ where
         RecordType(map) => ser_seq!(ser; tag(7), RecordMap(map)),
         RecordLit(map) => ser_seq!(ser; tag(8), RecordMap(map)),
         UnionType(map) => ser_seq!(ser; tag(11), UnionMap(map)),
-        UnionLit(l, x, map) => {
-            ser_seq!(ser; tag(12), label(l), expr(x), UnionMap(map))
-        }
         Field(x, l) => ser_seq!(ser; tag(9), expr(x), label(l)),
         BinOp(op, x, y) => {
             use dhall_syntax::BinOp::*;
@@ -542,6 +587,7 @@ where
     let mode = match import.mode {
         ImportMode::Code => 0,
         ImportMode::RawText => 1,
+        ImportMode::Location => 2,
     };
     ser_seq.serialize_element(&U64(mode))?;
 
@@ -565,12 +611,14 @@ where
         ImportLocation::Remote(url) => {
             match &url.headers {
                 None => ser_seq.serialize_element(&Null)?,
-                Some(location_hashed) => ser_seq.serialize_element(
-                    &self::Serialize::Import(&Import {
-                        mode: ImportMode::Code,
-                        location_hashed: location_hashed.as_ref().clone(),
-                    }),
-                )?,
+                Some(location_hashed) => {
+                    ser_seq.serialize_element(&self::Serialize::Expr(
+                        &SubExpr::from_expr_no_note(ExprF::Embed(Import {
+                            mode: ImportMode::Code,
+                            location_hashed: location_hashed.as_ref().clone(),
+                        })),
+                    ))?
+                }
             };
             ser_seq.serialize_element(&url.authority)?;
             for p in &url.path {
@@ -617,7 +665,6 @@ impl<'a> serde::ser::Serialize for Serialize<'a> {
                     (cbor::Value::String(k.into()), v)
                 }))
             }
-            Serialize::Import(import) => serialize_import(ser, import),
         }
     }
 }
@@ -641,3 +688,26 @@ fn collect_nested_applications<'a, N, E>(
     let e = go(e, &mut vec);
     (e, vec)
 }
+
+type LetBinding<'a, N, E> =
+    (&'a Label, &'a Option<SubExpr<N, E>>, &'a SubExpr<N, E>);
+
+fn collect_nested_lets<'a, N, E>(
+    e: &'a SubExpr<N, E>,
+) -> (&'a SubExpr<N, E>, Vec<LetBinding<'a, N, E>>) {
+    fn go<'a, N, E>(
+        e: &'a SubExpr<N, E>,
+        vec: &mut Vec<LetBinding<'a, N, E>>,
+    ) -> &'a SubExpr<N, E> {
+        match e.as_ref() {
+            ExprF::Let(l, t, v, e) => {
+                vec.push((l, t, v));
+                go(e, vec)
+            }
+            _ => e,
+        }
+    }
+    let mut vec = vec![];
+    let e = go(e, &mut vec);
+    (e, vec)
+}
diff --git a/dhall/src/phase/normalize.rs b/dhall/src/phase/normalize.rs
index 35d32cb..395cf28 100644
--- a/dhall/src/phase/normalize.rs
+++ b/dhall/src/phase/normalize.rs
@@ -47,6 +47,16 @@ pub fn apply_builtin(b: Builtin, args: Vec<Thunk>) -> Value {
             )),
             _ => Err(()),
         },
+        (NaturalSubtract, [a, b, r..]) => {
+            match (&*a.as_value(), &*b.as_value()) {
+                (NaturalLit(a), NaturalLit(b)) => {
+                    Ok((r, NaturalLit(if b > a { b - a } else { 0 })))
+                }
+                (NaturalLit(0), b) => Ok((r, b.clone())),
+                (_, NaturalLit(0)) => Ok((r, NaturalLit(0))),
+                _ => Err(()),
+            }
+        }
         (IntegerShow, [n, r..]) => match &*n.as_value() {
             IntegerLit(n) => {
                 let s = if *n < 0 {
@@ -72,6 +82,17 @@ pub fn apply_builtin(b: Builtin, args: Vec<Thunk>) -> Value {
         (TextShow, [v, r..]) => match &*v.as_value() {
             TextLit(elts) => {
                 match elts.as_slice() {
+                    // Empty string literal.
+                    [] => {
+                        // Printing InterpolatedText takes care of all the escaping
+                        let txt: InterpolatedText<X> =
+                            std::iter::empty().collect();
+                        let s = txt.to_string();
+                        Ok((
+                            r,
+                            TextLit(vec![InterpolatedTextContents::Text(s)]),
+                        ))
+                    }
                     // If there are no interpolations (invariants ensure that when there are no
                     // interpolations, there is a single Text item) in the literal.
                     [InterpolatedTextContents::Text(s)] => {
@@ -611,7 +632,7 @@ fn apply_binop<'a>(o: BinOp, x: &'a Thunk, y: &'a Thunk) -> Option<Ret<'a>> {
 
 pub fn normalize_one_layer(expr: ExprF<Thunk, X>) -> Value {
     use Value::{
-        BoolLit, DoubleLit, EmptyListLit, EmptyOptionalLit, IntegerLit, Lam,
+        AppliedBuiltin, BoolLit, DoubleLit, EmptyListLit, IntegerLit, Lam,
         NEListLit, NEOptionalLit, NaturalLit, Pi, RecordLit, RecordType,
         TextLit, UnionConstructor, UnionLit, UnionType,
     };
@@ -639,13 +660,21 @@ pub fn normalize_one_layer(expr: ExprF<Thunk, X>) -> Value {
         ExprF::NaturalLit(n) => Ret::Value(NaturalLit(n)),
         ExprF::IntegerLit(n) => Ret::Value(IntegerLit(n)),
         ExprF::DoubleLit(n) => Ret::Value(DoubleLit(n)),
-        ExprF::OldOptionalLit(None, t) => {
-            Ret::Value(EmptyOptionalLit(TypeThunk::from_thunk(t)))
-        }
-        ExprF::OldOptionalLit(Some(e), _) => Ret::Value(NEOptionalLit(e)),
         ExprF::SomeLit(e) => Ret::Value(NEOptionalLit(e)),
-        ExprF::EmptyListLit(t) => {
-            Ret::Value(EmptyListLit(TypeThunk::from_thunk(t)))
+        ExprF::EmptyListLit(ref t) => {
+            // Check if the type is of the form `List x`
+            let t_borrow = t.as_value();
+            match &*t_borrow {
+                AppliedBuiltin(Builtin::List, args) if args.len() == 1 => {
+                    Ret::Value(EmptyListLit(TypeThunk::from_thunk(
+                        args[0].clone(),
+                    )))
+                }
+                _ => {
+                    drop(t_borrow);
+                    Ret::Expr(expr)
+                }
+            }
         }
         ExprF::NEListLit(elts) => {
             Ret::Value(NEListLit(elts.into_iter().collect()))
@@ -658,13 +687,6 @@ pub fn normalize_one_layer(expr: ExprF<Thunk, X>) -> Value {
                 .map(|(k, t)| (k, TypeThunk::from_thunk(t)))
                 .collect(),
         )),
-        ExprF::UnionLit(l, x, kts) => Ret::Value(UnionLit(
-            l,
-            x,
-            kts.into_iter()
-                .map(|(k, t)| (k, t.map(|t| TypeThunk::from_thunk(t))))
-                .collect(),
-        )),
         ExprF::UnionType(kts) => Ret::Value(UnionType(
             kts.into_iter()
                 .map(|(k, t)| (k, t.map(|t| TypeThunk::from_thunk(t))))
diff --git a/dhall/src/phase/resolve.rs b/dhall/src/phase/resolve.rs
index c4d7e5f..abcee7e 100644
--- a/dhall/src/phase/resolve.rs
+++ b/dhall/src/phase/resolve.rs
@@ -86,7 +86,7 @@ fn do_resolve_expr(
             }
         }
     };
-    let expr = expr.traverse_embed(resolve)?;
+    let expr = expr.traverse_resolve(resolve)?;
     Ok(Resolved(expr))
 }
 
@@ -100,7 +100,7 @@ pub fn skip_resolve_expr(
     let resolve = |import: &Import| -> Result<Normalized, ImportError> {
         Err(ImportError::UnexpectedImport(import.clone()))
     };
-    let expr = expr.traverse_embed(resolve)?;
+    let expr = expr.traverse_resolve(resolve)?;
     Ok(Resolved(expr))
 }
 
@@ -110,24 +110,35 @@ mod spec_tests {
 
     macro_rules! import_success {
         ($name:ident, $path:expr) => {
-            make_spec_test!(Import, Success, $name, &("success/".to_owned() + $path));
+            make_spec_test!(Import, Success, $name, &("../dhall-lang/tests/import/success/".to_owned() + $path));
         };
     }
 
     // macro_rules! import_failure {
     //     ($name:ident, $path:expr) => {
-    //         make_spec_test!(Import, Failure, $name, &("failure/".to_owned() + $path));
+    //         make_spec_test!(Import, Failure, $name, &("../dhall-lang/tests/import/failure/".to_owned() + $path));
     //     };
     // }
 
     // import_success!(success_alternativeEnvNatural, "alternativeEnvNatural");
     // import_success!(success_alternativeEnvSimple, "alternativeEnvSimple");
+    // import_success!(success_alternativeHashMismatch, "alternativeHashMismatch");
     // import_success!(success_alternativeNatural, "alternativeNatural");
+    // import_success!(success_alternativeParseError, "alternativeParseError");
+    // import_success!(success_alternativeTypeError, "alternativeTypeError");
+    // import_success!(success_asLocation, "asLocation");
     // import_success!(success_asText, "asText");
+    // import_success!(success_customHeaders, "customHeaders");
     import_success!(success_fieldOrder, "fieldOrder");
+    // note: this one needs special setup with env variables
+    // import_success!(success_hashFromCache, "hashFromCache");
+    // import_success!(success_headerForwarding, "headerForwarding");
+    // import_success!(success_nestedHash, "nestedHash");
+    // import_success!(success_noHeaderForwarding, "noHeaderForwarding");
     // import_failure!(failure_alternativeEnv, "alternativeEnv");
     // import_failure!(failure_alternativeEnvMissing, "alternativeEnvMissing");
     // import_failure!(failure_cycle, "cycle");
+    // import_failure!(failure_hashMismatch, "hashMismatch");
     // import_failure!(failure_missing, "missing");
     // import_failure!(failure_referentiallyInsane, "referentiallyInsane");
 }
diff --git a/dhall/src/phase/typecheck.rs b/dhall/src/phase/typecheck.rs
index a3f676c..2e4642c 100644
--- a/dhall/src/phase/typecheck.rs
+++ b/dhall/src/phase/typecheck.rs
@@ -164,37 +164,6 @@ fn tck_union_type(
     ))
 }
 
-fn tck_list_type(ctx: &TypecheckContext, t: Type) -> Result<Typed, TypeError> {
-    use crate::error::TypeMessage::*;
-    ensure_simple_type!(
-        t,
-        TypeError::new(ctx, InvalidListType(t.to_normalized())),
-    );
-    Ok(Typed::from_thunk_and_type(
-        Value::from_builtin(Builtin::List)
-            .app(t.to_value())
-            .into_thunk(),
-        Type::from_const(Const::Type),
-    ))
-}
-
-fn tck_optional_type(
-    ctx: &TypecheckContext,
-    t: Type,
-) -> Result<Typed, TypeError> {
-    use crate::error::TypeMessage::*;
-    ensure_simple_type!(
-        t,
-        TypeError::new(ctx, InvalidOptionalType(t.to_normalized())),
-    );
-    Ok(Typed::from_thunk_and_type(
-        Value::from_builtin(Builtin::Optional)
-            .app(t.to_value())
-            .into_thunk(),
-        Type::from_const(Const::Type),
-    ))
-}
-
 fn function_check(a: Const, b: Const) -> Result<Const, ()> {
     use dhall_syntax::Const::*;
     match (a, b) {
@@ -243,6 +212,7 @@ fn type_of_builtin(b: Builtin) -> Expr<X, X> {
         ),
         NaturalToInteger => dhall::expr!(Natural -> Integer),
         NaturalShow => dhall::expr!(Natural -> Text),
+        NaturalSubtract => dhall::expr!(Natural -> Natural -> Natural),
 
         IntegerToDouble => dhall::expr!(Integer -> Double),
         IntegerShow => dhall::expr!(Integer -> Text),
@@ -329,9 +299,7 @@ fn type_with(
     ctx: &TypecheckContext,
     e: SubExpr<Span, Normalized>,
 ) -> Result<Typed, TypeError> {
-    use dhall_syntax::ExprF::{
-        Annot, App, Embed, Lam, Let, OldOptionalLit, Pi, SomeLit, Var,
-    };
+    use dhall_syntax::ExprF::{Annot, Embed, Lam, Let, Pi, Var};
 
     use Ret::*;
     Ok(match e.as_ref() {
@@ -364,18 +332,6 @@ fn type_with(
             let v = type_with(ctx, v)?;
             return type_with(&ctx.insert_value(x, v.clone())?, e.clone());
         }
-        OldOptionalLit(None, t) => {
-            let none = SubExpr::from_builtin(Builtin::OptionalNone);
-            let e = e.rewrap(App(none, t.clone()));
-            return type_with(ctx, e);
-        }
-        OldOptionalLit(Some(x), t) => {
-            let optional = SubExpr::from_builtin(Builtin::Optional);
-            let x = x.rewrap(SomeLit(x.clone()));
-            let t = t.rewrap(App(optional, t.clone()));
-            let e = e.rewrap(Annot(x, t));
-            return type_with(ctx, e);
-        }
         Embed(p) => p.clone().into_typed(),
         Var(var) => match ctx.lookup(&var) {
             Some(typed) => typed,
@@ -423,12 +379,9 @@ fn type_last_layer(
     let mkerr = |msg: TypeMessage| TypeError::new(ctx, msg);
 
     match e {
-        Lam(_, _, _)
-        | Pi(_, _, _)
-        | Let(_, _, _, _)
-        | OldOptionalLit(_, _)
-        | Embed(_)
-        | Var(_) => unreachable!(),
+        Lam(_, _, _) | Pi(_, _, _) | Let(_, _, _, _) | Embed(_) | Var(_) => {
+            unreachable!()
+        }
         App(f, a) => {
             let tf = f.get_type()?;
             let (x, tx, tb) = match &tf.to_value() {
@@ -477,7 +430,17 @@ fn type_last_layer(
         }
         EmptyListLit(t) => {
             let t = t.to_type();
-            Ok(RetTypeOnly(tck_list_type(ctx, t)?.to_type()))
+            match &t.to_value() {
+                Value::AppliedBuiltin(dhall_syntax::Builtin::List, args)
+                    if args.len() == 1 => {}
+                _ => {
+                    return Err(TypeError::new(
+                        ctx,
+                        InvalidListType(t.to_normalized()),
+                    ))
+                }
+            }
+            Ok(RetTypeOnly(t))
         }
         NEListLit(xs) => {
             let mut iter = xs.iter().enumerate();
@@ -493,12 +456,38 @@ fn type_last_layer(
                     ))
                 );
             }
-            let t = x.get_type()?.into_owned();
-            Ok(RetTypeOnly(tck_list_type(ctx, t)?.to_type()))
+            let t = x.get_type()?;
+            ensure_simple_type!(
+                t,
+                TypeError::new(ctx, InvalidListType(t.to_normalized())),
+            );
+
+            Ok(RetTypeOnly(
+                Typed::from_thunk_and_type(
+                    Value::from_builtin(dhall_syntax::Builtin::List)
+                        .app(t.to_value())
+                        .into_thunk(),
+                    Type::from_const(dhall_syntax::Const::Type),
+                )
+                .to_type(),
+            ))
         }
         SomeLit(x) => {
             let t = x.get_type()?.into_owned();
-            Ok(RetTypeOnly(tck_optional_type(ctx, t)?.to_type()))
+            ensure_simple_type!(
+                t,
+                TypeError::new(ctx, InvalidOptionalType(t.to_normalized())),
+            );
+
+            Ok(RetTypeOnly(
+                Typed::from_thunk_and_type(
+                    Value::from_builtin(dhall_syntax::Builtin::Optional)
+                        .app(t.to_value())
+                        .into_thunk(),
+                    Type::from_const(dhall_syntax::Const::Type),
+                )
+                .to_type(),
+            ))
         }
         RecordType(kts) => Ok(RetWhole(tck_record_type(
             ctx,
@@ -517,15 +506,6 @@ fn type_last_layer(
             )?
             .into_type(),
         )),
-        UnionLit(x, v, kvs) => {
-            use std::iter::once;
-            let kts = kvs
-                .iter()
-                .map(|(x, v)| Ok((x.clone(), v.as_ref().map(|v| v.to_type()))));
-            let t = v.get_type()?.into_owned();
-            let kts = kts.chain(once(Ok((x.clone(), Some(t)))));
-            Ok(RetTypeOnly(tck_union_type(ctx, kts)?.to_type()))
-        }
         Field(r, x) => {
             match &r.get_type()?.to_value() {
                 Value::RecordType(kts) => match kts.get(&x) {
@@ -840,7 +820,7 @@ fn type_last_layer(
                 RightBiasedRecordMerge => unreachable!(),
                 RecursiveRecordMerge => unreachable!(),
                 RecursiveRecordTypeMerge => unreachable!(),
-                _ => return Err(mkerr(Unimplemented)),
+                ImportAlt => unreachable!("There should remain no import alternatives in a resolved expression"),
             })?;
 
             ensure_equal!(
@@ -985,394 +965,3 @@ pub fn typecheck_with(e: Resolved, ty: &Type) -> Result<Typed, TypeError> {
 pub fn skip_typecheck(e: Resolved) -> Typed {
     Typed::from_thunk_untyped(Thunk::new(NormalizationContext::new(), e.0))
 }
-
-#[cfg(test)]
-mod spec_tests {
-    #![rustfmt::skip]
-
-    macro_rules! tc_success {
-        ($name:ident, $path:expr) => {
-            make_spec_test!(Typecheck, Success, $name, &("success/".to_owned() + $path));
-        };
-    }
-    macro_rules! tc_failure {
-        ($name:ident, $path:expr) => {
-            make_spec_test!(Typecheck, Failure, $name, &("failure/".to_owned() + $path));
-        };
-    }
-
-    macro_rules! ti_success {
-        ($name:ident, $path:expr) => {
-            make_spec_test!(TypeInference, Success, $name, &("success/".to_owned() + $path));
-        };
-    }
-    // macro_rules! ti_failure {
-    //     ($name:ident, $path:expr) => {
-    //         make_spec_test!(TypeInference, Failure, $name, &("failure/".to_owned() + $path));
-    //     };
-    // }
-
-    // tc_success!(tc_success_accessEncodedType, "accessEncodedType");
-    // tc_success!(tc_success_accessType, "accessType");
-    tc_success!(tc_success_prelude_Bool_and_0, "prelude/Bool/and/0");
-    tc_success!(tc_success_prelude_Bool_and_1, "prelude/Bool/and/1");
-    tc_success!(tc_success_prelude_Bool_build_0, "prelude/Bool/build/0");
-    tc_success!(tc_success_prelude_Bool_build_1, "prelude/Bool/build/1");
-    tc_success!(tc_success_prelude_Bool_even_0, "prelude/Bool/even/0");
-    tc_success!(tc_success_prelude_Bool_even_1, "prelude/Bool/even/1");
-    tc_success!(tc_success_prelude_Bool_even_2, "prelude/Bool/even/2");
-    tc_success!(tc_success_prelude_Bool_even_3, "prelude/Bool/even/3");
-    tc_success!(tc_success_prelude_Bool_fold_0, "prelude/Bool/fold/0");
-    tc_success!(tc_success_prelude_Bool_fold_1, "prelude/Bool/fold/1");
-    tc_success!(tc_success_prelude_Bool_not_0, "prelude/Bool/not/0");
-    tc_success!(tc_success_prelude_Bool_not_1, "prelude/Bool/not/1");
-    tc_success!(tc_success_prelude_Bool_odd_0, "prelude/Bool/odd/0");
-    tc_success!(tc_success_prelude_Bool_odd_1, "prelude/Bool/odd/1");
-    tc_success!(tc_success_prelude_Bool_odd_2, "prelude/Bool/odd/2");
-    tc_success!(tc_success_prelude_Bool_odd_3, "prelude/Bool/odd/3");
-    tc_success!(tc_success_prelude_Bool_or_0, "prelude/Bool/or/0");
-    tc_success!(tc_success_prelude_Bool_or_1, "prelude/Bool/or/1");
-    tc_success!(tc_success_prelude_Bool_show_0, "prelude/Bool/show/0");
-    tc_success!(tc_success_prelude_Bool_show_1, "prelude/Bool/show/1");
-    tc_success!(tc_success_prelude_Double_show_0, "prelude/Double/show/0");
-    tc_success!(tc_success_prelude_Double_show_1, "prelude/Double/show/1");
-    tc_success!(tc_success_prelude_Integer_show_0, "prelude/Integer/show/0");
-    tc_success!(tc_success_prelude_Integer_show_1, "prelude/Integer/show/1");
-    tc_success!(tc_success_prelude_Integer_toDouble_0, "prelude/Integer/toDouble/0");
-    tc_success!(tc_success_prelude_Integer_toDouble_1, "prelude/Integer/toDouble/1");
-    tc_success!(tc_success_prelude_List_all_0, "prelude/List/all/0");
-    tc_success!(tc_success_prelude_List_all_1, "prelude/List/all/1");
-    tc_success!(tc_success_prelude_List_any_0, "prelude/List/any/0");
-    tc_success!(tc_success_prelude_List_any_1, "prelude/List/any/1");
-    tc_success!(tc_success_prelude_List_build_0, "prelude/List/build/0");
-    tc_success!(tc_success_prelude_List_build_1, "prelude/List/build/1");
-    tc_success!(tc_success_prelude_List_concat_0, "prelude/List/concat/0");
-    tc_success!(tc_success_prelude_List_concat_1, "prelude/List/concat/1");
-    tc_success!(tc_success_prelude_List_concatMap_0, "prelude/List/concatMap/0");
-    tc_success!(tc_success_prelude_List_concatMap_1, "prelude/List/concatMap/1");
-    tc_success!(tc_success_prelude_List_filter_0, "prelude/List/filter/0");
-    tc_success!(tc_success_prelude_List_filter_1, "prelude/List/filter/1");
-    tc_success!(tc_success_prelude_List_fold_0, "prelude/List/fold/0");
-    tc_success!(tc_success_prelude_List_fold_1, "prelude/List/fold/1");
-    tc_success!(tc_success_prelude_List_fold_2, "prelude/List/fold/2");
-    tc_success!(tc_success_prelude_List_generate_0, "prelude/List/generate/0");
-    tc_success!(tc_success_prelude_List_generate_1, "prelude/List/generate/1");
-    tc_success!(tc_success_prelude_List_head_0, "prelude/List/head/0");
-    tc_success!(tc_success_prelude_List_head_1, "prelude/List/head/1");
-    tc_success!(tc_success_prelude_List_indexed_0, "prelude/List/indexed/0");
-    tc_success!(tc_success_prelude_List_indexed_1, "prelude/List/indexed/1");
-    tc_success!(tc_success_prelude_List_iterate_0, "prelude/List/iterate/0");
-    tc_success!(tc_success_prelude_List_iterate_1, "prelude/List/iterate/1");
-    tc_success!(tc_success_prelude_List_last_0, "prelude/List/last/0");
-    tc_success!(tc_success_prelude_List_last_1, "prelude/List/last/1");
-    tc_success!(tc_success_prelude_List_length_0, "prelude/List/length/0");
-    tc_success!(tc_success_prelude_List_length_1, "prelude/List/length/1");
-    tc_success!(tc_success_prelude_List_map_0, "prelude/List/map/0");
-    tc_success!(tc_success_prelude_List_map_1, "prelude/List/map/1");
-    tc_success!(tc_success_prelude_List_null_0, "prelude/List/null/0");
-    tc_success!(tc_success_prelude_List_null_1, "prelude/List/null/1");
-    tc_success!(tc_success_prelude_List_replicate_0, "prelude/List/replicate/0");
-    tc_success!(tc_success_prelude_List_replicate_1, "prelude/List/replicate/1");
-    tc_success!(tc_success_prelude_List_reverse_0, "prelude/List/reverse/0");
-    tc_success!(tc_success_prelude_List_reverse_1, "prelude/List/reverse/1");
-    tc_success!(tc_success_prelude_List_shifted_0, "prelude/List/shifted/0");
-    tc_success!(tc_success_prelude_List_shifted_1, "prelude/List/shifted/1");
-    tc_success!(tc_success_prelude_List_unzip_0, "prelude/List/unzip/0");
-    tc_success!(tc_success_prelude_List_unzip_1, "prelude/List/unzip/1");
-    tc_success!(tc_success_prelude_Monoid_00, "prelude/Monoid/00");
-    tc_success!(tc_success_prelude_Monoid_01, "prelude/Monoid/01");
-    tc_success!(tc_success_prelude_Monoid_02, "prelude/Monoid/02");
-    tc_success!(tc_success_prelude_Monoid_03, "prelude/Monoid/03");
-    tc_success!(tc_success_prelude_Monoid_04, "prelude/Monoid/04");
-    tc_success!(tc_success_prelude_Monoid_05, "prelude/Monoid/05");
-    tc_success!(tc_success_prelude_Monoid_06, "prelude/Monoid/06");
-    tc_success!(tc_success_prelude_Monoid_07, "prelude/Monoid/07");
-    tc_success!(tc_success_prelude_Monoid_08, "prelude/Monoid/08");
-    tc_success!(tc_success_prelude_Monoid_09, "prelude/Monoid/09");
-    tc_success!(tc_success_prelude_Monoid_10, "prelude/Monoid/10");
-    tc_success!(tc_success_prelude_Natural_build_0, "prelude/Natural/build/0");
-    tc_success!(tc_success_prelude_Natural_build_1, "prelude/Natural/build/1");
-    tc_success!(tc_success_prelude_Natural_enumerate_0, "prelude/Natural/enumerate/0");
-    tc_success!(tc_success_prelude_Natural_enumerate_1, "prelude/Natural/enumerate/1");
-    tc_success!(tc_success_prelude_Natural_even_0, "prelude/Natural/even/0");
-    tc_success!(tc_success_prelude_Natural_even_1, "prelude/Natural/even/1");
-    tc_success!(tc_success_prelude_Natural_fold_0, "prelude/Natural/fold/0");
-    tc_success!(tc_success_prelude_Natural_fold_1, "prelude/Natural/fold/1");
-    tc_success!(tc_success_prelude_Natural_fold_2, "prelude/Natural/fold/2");
-    tc_success!(tc_success_prelude_Natural_isZero_0, "prelude/Natural/isZero/0");
-    tc_success!(tc_success_prelude_Natural_isZero_1, "prelude/Natural/isZero/1");
-    tc_success!(tc_success_prelude_Natural_odd_0, "prelude/Natural/odd/0");
-    tc_success!(tc_success_prelude_Natural_odd_1, "prelude/Natural/odd/1");
-    tc_success!(tc_success_prelude_Natural_product_0, "prelude/Natural/product/0");
-    tc_success!(tc_success_prelude_Natural_product_1, "prelude/Natural/product/1");
-    tc_success!(tc_success_prelude_Natural_show_0, "prelude/Natural/show/0");
-    tc_success!(tc_success_prelude_Natural_show_1, "prelude/Natural/show/1");
-    tc_success!(tc_success_prelude_Natural_sum_0, "prelude/Natural/sum/0");
-    tc_success!(tc_success_prelude_Natural_sum_1, "prelude/Natural/sum/1");
-    tc_success!(tc_success_prelude_Natural_toDouble_0, "prelude/Natural/toDouble/0");
-    tc_success!(tc_success_prelude_Natural_toDouble_1, "prelude/Natural/toDouble/1");
-    tc_success!(tc_success_prelude_Natural_toInteger_0, "prelude/Natural/toInteger/0");
-    tc_success!(tc_success_prelude_Natural_toInteger_1, "prelude/Natural/toInteger/1");
-    tc_success!(tc_success_prelude_Optional_all_0, "prelude/Optional/all/0");
-    tc_success!(tc_success_prelude_Optional_all_1, "prelude/Optional/all/1");
-    tc_success!(tc_success_prelude_Optional_any_0, "prelude/Optional/any/0");
-    tc_success!(tc_success_prelude_Optional_any_1, "prelude/Optional/any/1");
-    tc_success!(tc_success_prelude_Optional_build_0, "prelude/Optional/build/0");
-    tc_success!(tc_success_prelude_Optional_build_1, "prelude/Optional/build/1");
-    tc_success!(tc_success_prelude_Optional_concat_0, "prelude/Optional/concat/0");
-    tc_success!(tc_success_prelude_Optional_concat_1, "prelude/Optional/concat/1");
-    tc_success!(tc_success_prelude_Optional_concat_2, "prelude/Optional/concat/2");
-    tc_success!(tc_success_prelude_Optional_filter_0, "prelude/Optional/filter/0");
-    tc_success!(tc_success_prelude_Optional_filter_1, "prelude/Optional/filter/1");
-    tc_success!(tc_success_prelude_Optional_fold_0, "prelude/Optional/fold/0");
-    tc_success!(tc_success_prelude_Optional_fold_1, "prelude/Optional/fold/1");
-    tc_success!(tc_success_prelude_Optional_head_0, "prelude/Optional/head/0");
-    tc_success!(tc_success_prelude_Optional_head_1, "prelude/Optional/head/1");
-    tc_success!(tc_success_prelude_Optional_head_2, "prelude/Optional/head/2");
-    tc_success!(tc_success_prelude_Optional_last_0, "prelude/Optional/last/0");
-    tc_success!(tc_success_prelude_Optional_last_1, "prelude/Optional/last/1");
-    tc_success!(tc_success_prelude_Optional_last_2, "prelude/Optional/last/2");
-    tc_success!(tc_success_prelude_Optional_length_0, "prelude/Optional/length/0");
-    tc_success!(tc_success_prelude_Optional_length_1, "prelude/Optional/length/1");
-    tc_success!(tc_success_prelude_Optional_map_0, "prelude/Optional/map/0");
-    tc_success!(tc_success_prelude_Optional_map_1, "prelude/Optional/map/1");
-    tc_success!(tc_success_prelude_Optional_null_0, "prelude/Optional/null/0");
-    tc_success!(tc_success_prelude_Optional_null_1, "prelude/Optional/null/1");
-    tc_success!(tc_success_prelude_Optional_toList_0, "prelude/Optional/toList/0");
-    tc_success!(tc_success_prelude_Optional_toList_1, "prelude/Optional/toList/1");
-    tc_success!(tc_success_prelude_Optional_unzip_0, "prelude/Optional/unzip/0");
-    tc_success!(tc_success_prelude_Optional_unzip_1, "prelude/Optional/unzip/1");
-    tc_success!(tc_success_prelude_Text_concat_0, "prelude/Text/concat/0");
-    tc_success!(tc_success_prelude_Text_concat_1, "prelude/Text/concat/1");
-    tc_success!(tc_success_prelude_Text_concatMap_0, "prelude/Text/concatMap/0");
-    tc_success!(tc_success_prelude_Text_concatMap_1, "prelude/Text/concatMap/1");
-    // tc_success!(tc_success_prelude_Text_concatMapSep_0, "prelude/Text/concatMapSep/0");
-    // tc_success!(tc_success_prelude_Text_concatMapSep_1, "prelude/Text/concatMapSep/1");
-    // tc_success!(tc_success_prelude_Text_concatSep_0, "prelude/Text/concatSep/0");
-    // tc_success!(tc_success_prelude_Text_concatSep_1, "prelude/Text/concatSep/1");
-    tc_success!(tc_success_recordOfRecordOfTypes, "recordOfRecordOfTypes");
-    tc_success!(tc_success_recordOfTypes, "recordOfTypes");
-    // tc_success!(tc_success_simple_access_0, "simple/access/0");
-    // tc_success!(tc_success_simple_access_1, "simple/access/1");
-    // tc_success!(tc_success_simple_anonymousFunctionsInTypes, "simple/anonymousFunctionsInTypes");
-    // tc_success!(tc_success_simple_fieldsAreTypes, "simple/fieldsAreTypes");
-    // tc_success!(tc_success_simple_kindParameter, "simple/kindParameter");
-    tc_success!(tc_success_simple_mergeEquivalence, "simple/mergeEquivalence");
-    // tc_success!(tc_success_simple_mixedFieldAccess, "simple/mixedFieldAccess");
-    tc_success!(tc_success_simple_unionsOfTypes, "simple/unionsOfTypes");
-
-    tc_failure!(tc_failure_combineMixedRecords, "combineMixedRecords");
-    tc_failure!(tc_failure_duplicateFields, "duplicateFields");
-    tc_failure!(tc_failure_hurkensParadox, "hurkensParadox");
-    // tc_failure!(tc_failure_importBoundary, "importBoundary");
-    tc_failure!(tc_failure_mixedUnions, "mixedUnions");
-    tc_failure!(tc_failure_preferMixedRecords, "preferMixedRecords");
-    tc_failure!(tc_failure_unit_FunctionApplicationArgumentNotMatch, "unit/FunctionApplicationArgumentNotMatch");
-    tc_failure!(tc_failure_unit_FunctionApplicationIsNotFunction, "unit/FunctionApplicationIsNotFunction");
-    tc_failure!(tc_failure_unit_FunctionArgumentTypeNotAType, "unit/FunctionArgumentTypeNotAType");
-    tc_failure!(tc_failure_unit_FunctionDependentType, "unit/FunctionDependentType");
-    tc_failure!(tc_failure_unit_FunctionDependentType2, "unit/FunctionDependentType2");
-    tc_failure!(tc_failure_unit_FunctionTypeArgumentTypeNotAType, "unit/FunctionTypeArgumentTypeNotAType");
-    tc_failure!(tc_failure_unit_FunctionTypeKindSort, "unit/FunctionTypeKindSort");
-    tc_failure!(tc_failure_unit_FunctionTypeTypeKind, "unit/FunctionTypeTypeKind");
-    tc_failure!(tc_failure_unit_FunctionTypeTypeSort, "unit/FunctionTypeTypeSort");
-    tc_failure!(tc_failure_unit_IfBranchesNotMatch, "unit/IfBranchesNotMatch");
-    tc_failure!(tc_failure_unit_IfBranchesNotType, "unit/IfBranchesNotType");
-    tc_failure!(tc_failure_unit_IfNotBool, "unit/IfNotBool");
-    tc_failure!(tc_failure_unit_LetWithWrongAnnotation, "unit/LetWithWrongAnnotation");
-    tc_failure!(tc_failure_unit_ListLiteralEmptyNotType, "unit/ListLiteralEmptyNotType");
-    tc_failure!(tc_failure_unit_ListLiteralNotType, "unit/ListLiteralNotType");
-    tc_failure!(tc_failure_unit_ListLiteralTypesNotMatch, "unit/ListLiteralTypesNotMatch");
-    tc_failure!(tc_failure_unit_MergeAlternativeHasNoHandler, "unit/MergeAlternativeHasNoHandler");
-    tc_failure!(tc_failure_unit_MergeAnnotationNotType, "unit/MergeAnnotationNotType");
-    tc_failure!(tc_failure_unit_MergeEmptyWithoutAnnotation, "unit/MergeEmptyWithoutAnnotation");
-    tc_failure!(tc_failure_unit_MergeHandlerNotFunction, "unit/MergeHandlerNotFunction");
-    tc_failure!(tc_failure_unit_MergeHandlerNotInUnion, "unit/MergeHandlerNotInUnion");
-    tc_failure!(tc_failure_unit_MergeHandlerNotMatchAlternativeType, "unit/MergeHandlerNotMatchAlternativeType");
-    tc_failure!(tc_failure_unit_MergeHandlersWithDifferentType, "unit/MergeHandlersWithDifferentType");
-    tc_failure!(tc_failure_unit_MergeLhsNotRecord, "unit/MergeLhsNotRecord");
-    tc_failure!(tc_failure_unit_MergeRhsNotUnion, "unit/MergeRhsNotUnion");
-    tc_failure!(tc_failure_unit_MergeWithWrongAnnotation, "unit/MergeWithWrongAnnotation");
-    tc_failure!(tc_failure_unit_OperatorAndNotBool, "unit/OperatorAndNotBool");
-    tc_failure!(tc_failure_unit_OperatorEqualNotBool, "unit/OperatorEqualNotBool");
-    tc_failure!(tc_failure_unit_OperatorListConcatenateLhsNotList, "unit/OperatorListConcatenateLhsNotList");
-    tc_failure!(tc_failure_unit_OperatorListConcatenateListsNotMatch, "unit/OperatorListConcatenateListsNotMatch");
-    tc_failure!(tc_failure_unit_OperatorListConcatenateNotListsButMatch, "unit/OperatorListConcatenateNotListsButMatch");
-    tc_failure!(tc_failure_unit_OperatorListConcatenateRhsNotList, "unit/OperatorListConcatenateRhsNotList");
-    tc_failure!(tc_failure_unit_OperatorNotEqualNotBool, "unit/OperatorNotEqualNotBool");
-    tc_failure!(tc_failure_unit_OperatorOrNotBool, "unit/OperatorOrNotBool");
-    tc_failure!(tc_failure_unit_OperatorPlusNotNatural, "unit/OperatorPlusNotNatural");
-    tc_failure!(tc_failure_unit_OperatorTextConcatenateLhsNotText, "unit/OperatorTextConcatenateLhsNotText");
-    tc_failure!(tc_failure_unit_OperatorTextConcatenateRhsNotText, "unit/OperatorTextConcatenateRhsNotText");
-    tc_failure!(tc_failure_unit_OperatorTimesNotNatural, "unit/OperatorTimesNotNatural");
-    tc_failure!(tc_failure_unit_RecordMixedKinds, "unit/RecordMixedKinds");
-    tc_failure!(tc_failure_unit_RecordMixedKinds2, "unit/RecordMixedKinds2");
-    tc_failure!(tc_failure_unit_RecordMixedKinds3, "unit/RecordMixedKinds3");
-    tc_failure!(tc_failure_unit_RecordProjectionEmpty, "unit/RecordProjectionEmpty");
-    tc_failure!(tc_failure_unit_RecordProjectionNotPresent, "unit/RecordProjectionNotPresent");
-    tc_failure!(tc_failure_unit_RecordProjectionNotRecord, "unit/RecordProjectionNotRecord");
-    tc_failure!(tc_failure_unit_RecordSelectionEmpty, "unit/RecordSelectionEmpty");
-    tc_failure!(tc_failure_unit_RecordSelectionNotPresent, "unit/RecordSelectionNotPresent");
-    tc_failure!(tc_failure_unit_RecordSelectionNotRecord, "unit/RecordSelectionNotRecord");
-    tc_failure!(tc_failure_unit_RecordSelectionTypeNotUnionType, "unit/RecordSelectionTypeNotUnionType");
-    tc_failure!(tc_failure_unit_RecordTypeMixedKinds, "unit/RecordTypeMixedKinds");
-    tc_failure!(tc_failure_unit_RecordTypeMixedKinds2, "unit/RecordTypeMixedKinds2");
-    tc_failure!(tc_failure_unit_RecordTypeMixedKinds3, "unit/RecordTypeMixedKinds3");
-    tc_failure!(tc_failure_unit_RecordTypeValueMember, "unit/RecordTypeValueMember");
-    tc_failure!(tc_failure_unit_RecursiveRecordMergeLhsNotRecord, "unit/RecursiveRecordMergeLhsNotRecord");
-    tc_failure!(tc_failure_unit_RecursiveRecordMergeMixedKinds, "unit/RecursiveRecordMergeMixedKinds");
-    tc_failure!(tc_failure_unit_RecursiveRecordMergeOverlapping, "unit/RecursiveRecordMergeOverlapping");
-    tc_failure!(tc_failure_unit_RecursiveRecordMergeRhsNotRecord, "unit/RecursiveRecordMergeRhsNotRecord");
-    tc_failure!(tc_failure_unit_RecursiveRecordTypeMergeLhsNotRecordType, "unit/RecursiveRecordTypeMergeLhsNotRecordType");
-    tc_failure!(tc_failure_unit_RecursiveRecordTypeMergeOverlapping, "unit/RecursiveRecordTypeMergeOverlapping");
-    tc_failure!(tc_failure_unit_RecursiveRecordTypeMergeRhsNotRecordType, "unit/RecursiveRecordTypeMergeRhsNotRecordType");
-    tc_failure!(tc_failure_unit_RightBiasedRecordMergeLhsNotRecord, "unit/RightBiasedRecordMergeLhsNotRecord");
-    tc_failure!(tc_failure_unit_RightBiasedRecordMergeMixedKinds, "unit/RightBiasedRecordMergeMixedKinds");
-    tc_failure!(tc_failure_unit_RightBiasedRecordMergeMixedKinds2, "unit/RightBiasedRecordMergeMixedKinds2");
-    tc_failure!(tc_failure_unit_RightBiasedRecordMergeMixedKinds3, "unit/RightBiasedRecordMergeMixedKinds3");
-    tc_failure!(tc_failure_unit_RightBiasedRecordMergeRhsNotRecord, "unit/RightBiasedRecordMergeRhsNotRecord");
-    tc_failure!(tc_failure_unit_SomeNotType, "unit/SomeNotType");
-    tc_failure!(tc_failure_unit_Sort, "unit/Sort");
-    tc_failure!(tc_failure_unit_TextLiteralInterpolateNotText, "unit/TextLiteralInterpolateNotText");
-    tc_failure!(tc_failure_unit_TypeAnnotationWrong, "unit/TypeAnnotationWrong");
-    tc_failure!(tc_failure_unit_UnionConstructorFieldNotPresent, "unit/UnionConstructorFieldNotPresent");
-    tc_failure!(tc_failure_unit_UnionTypeMixedKinds, "unit/UnionTypeMixedKinds");
-    tc_failure!(tc_failure_unit_UnionTypeMixedKinds2, "unit/UnionTypeMixedKinds2");
-    tc_failure!(tc_failure_unit_UnionTypeMixedKinds3, "unit/UnionTypeMixedKinds3");
-    tc_failure!(tc_failure_unit_UnionTypeNotType, "unit/UnionTypeNotType");
-    tc_failure!(tc_failure_unit_VariableFree, "unit/VariableFree");
-
-    ti_success!(ti_success_simple_alternativesAreTypes, "simple/alternativesAreTypes");
-    ti_success!(ti_success_simple_kindParameter, "simple/kindParameter");
-    ti_success!(ti_success_unit_Bool, "unit/Bool");
-    ti_success!(ti_success_unit_Double, "unit/Double");
-    ti_success!(ti_success_unit_DoubleLiteral, "unit/DoubleLiteral");
-    ti_success!(ti_success_unit_DoubleShow, "unit/DoubleShow");
-    ti_success!(ti_success_unit_False, "unit/False");
-    ti_success!(ti_success_unit_Function, "unit/Function");
-    ti_success!(ti_success_unit_FunctionApplication, "unit/FunctionApplication");
-    ti_success!(ti_success_unit_FunctionNamedArg, "unit/FunctionNamedArg");
-    ti_success!(ti_success_unit_FunctionTypeKindKind, "unit/FunctionTypeKindKind");
-    ti_success!(ti_success_unit_FunctionTypeKindTerm, "unit/FunctionTypeKindTerm");
-    ti_success!(ti_success_unit_FunctionTypeKindType, "unit/FunctionTypeKindType");
-    ti_success!(ti_success_unit_FunctionTypeTermTerm, "unit/FunctionTypeTermTerm");
-    ti_success!(ti_success_unit_FunctionTypeTypeTerm, "unit/FunctionTypeTypeTerm");
-    ti_success!(ti_success_unit_FunctionTypeTypeType, "unit/FunctionTypeTypeType");
-    ti_success!(ti_success_unit_FunctionTypeUsingArgument, "unit/FunctionTypeUsingArgument");
-    ti_success!(ti_success_unit_If, "unit/If");
-    ti_success!(ti_success_unit_IfNormalizeArguments, "unit/IfNormalizeArguments");
-    ti_success!(ti_success_unit_Integer, "unit/Integer");
-    ti_success!(ti_success_unit_IntegerLiteral, "unit/IntegerLiteral");
-    ti_success!(ti_success_unit_IntegerShow, "unit/IntegerShow");
-    ti_success!(ti_success_unit_IntegerToDouble, "unit/IntegerToDouble");
-    ti_success!(ti_success_unit_Kind, "unit/Kind");
-    ti_success!(ti_success_unit_Let, "unit/Let");
-    ti_success!(ti_success_unit_LetNestedTypeSynonym, "unit/LetNestedTypeSynonym");
-    ti_success!(ti_success_unit_LetTypeSynonym, "unit/LetTypeSynonym");
-    ti_success!(ti_success_unit_LetWithAnnotation, "unit/LetWithAnnotation");
-    ti_success!(ti_success_unit_List, "unit/List");
-    ti_success!(ti_success_unit_ListBuild, "unit/ListBuild");
-    ti_success!(ti_success_unit_ListFold, "unit/ListFold");
-    ti_success!(ti_success_unit_ListHead, "unit/ListHead");
-    ti_success!(ti_success_unit_ListIndexed, "unit/ListIndexed");
-    ti_success!(ti_success_unit_ListLast, "unit/ListLast");
-    ti_success!(ti_success_unit_ListLength, "unit/ListLength");
-    ti_success!(ti_success_unit_ListLiteralEmpty, "unit/ListLiteralEmpty");
-    ti_success!(ti_success_unit_ListLiteralNormalizeArguments, "unit/ListLiteralNormalizeArguments");
-    ti_success!(ti_success_unit_ListLiteralOne, "unit/ListLiteralOne");
-    ti_success!(ti_success_unit_ListReverse, "unit/ListReverse");
-    ti_success!(ti_success_unit_MergeEmptyUnion, "unit/MergeEmptyUnion");
-    ti_success!(ti_success_unit_MergeOne, "unit/MergeOne");
-    ti_success!(ti_success_unit_MergeOneEmpty, "unit/MergeOneEmpty");
-    ti_success!(ti_success_unit_MergeOneWithAnnotation, "unit/MergeOneWithAnnotation");
-    ti_success!(ti_success_unit_Natural, "unit/Natural");
-    ti_success!(ti_success_unit_NaturalBuild, "unit/NaturalBuild");
-    ti_success!(ti_success_unit_NaturalEven, "unit/NaturalEven");
-    ti_success!(ti_success_unit_NaturalFold, "unit/NaturalFold");
-    ti_success!(ti_success_unit_NaturalIsZero, "unit/NaturalIsZero");
-    ti_success!(ti_success_unit_NaturalLiteral, "unit/NaturalLiteral");
-    ti_success!(ti_success_unit_NaturalOdd, "unit/NaturalOdd");
-    ti_success!(ti_success_unit_NaturalShow, "unit/NaturalShow");
-    ti_success!(ti_success_unit_NaturalToInteger, "unit/NaturalToInteger");
-    ti_success!(ti_success_unit_None, "unit/None");
-    ti_success!(ti_success_unit_OldOptionalNone, "unit/OldOptionalNone");
-    ti_success!(ti_success_unit_OldOptionalTrue, "unit/OldOptionalTrue");
-    ti_success!(ti_success_unit_OperatorAnd, "unit/OperatorAnd");
-    ti_success!(ti_success_unit_OperatorAndNormalizeArguments, "unit/OperatorAndNormalizeArguments");
-    ti_success!(ti_success_unit_OperatorEqual, "unit/OperatorEqual");
-    ti_success!(ti_success_unit_OperatorEqualNormalizeArguments, "unit/OperatorEqualNormalizeArguments");
-    ti_success!(ti_success_unit_OperatorListConcatenate, "unit/OperatorListConcatenate");
-    ti_success!(ti_success_unit_OperatorListConcatenateNormalizeArguments, "unit/OperatorListConcatenateNormalizeArguments");
-    ti_success!(ti_success_unit_OperatorNotEqual, "unit/OperatorNotEqual");
-    ti_success!(ti_success_unit_OperatorNotEqualNormalizeArguments, "unit/OperatorNotEqualNormalizeArguments");
-    ti_success!(ti_success_unit_OperatorOr, "unit/OperatorOr");
-    ti_success!(ti_success_unit_OperatorOrNormalizeArguments, "unit/OperatorOrNormalizeArguments");
-    ti_success!(ti_success_unit_OperatorPlus, "unit/OperatorPlus");
-    ti_success!(ti_success_unit_OperatorPlusNormalizeArguments, "unit/OperatorPlusNormalizeArguments");
-    ti_success!(ti_success_unit_OperatorTextConcatenate, "unit/OperatorTextConcatenate");
-    ti_success!(ti_success_unit_OperatorTextConcatenateNormalizeArguments, "unit/OperatorTextConcatenateNormalizeArguments");
-    ti_success!(ti_success_unit_OperatorTimes, "unit/OperatorTimes");
-    ti_success!(ti_success_unit_OperatorTimesNormalizeArguments, "unit/OperatorTimesNormalizeArguments");
-    ti_success!(ti_success_unit_Optional, "unit/Optional");
-    ti_success!(ti_success_unit_OptionalBuild, "unit/OptionalBuild");
-    ti_success!(ti_success_unit_OptionalFold, "unit/OptionalFold");
-    ti_success!(ti_success_unit_RecordEmpty, "unit/RecordEmpty");
-    ti_success!(ti_success_unit_RecordNestedKind, "unit/RecordNestedKind");
-    ti_success!(ti_success_unit_RecordNestedKindLike, "unit/RecordNestedKindLike");
-    ti_success!(ti_success_unit_RecordNestedType, "unit/RecordNestedType");
-    ti_success!(ti_success_unit_RecordNestedTypeLike, "unit/RecordNestedTypeLike");
-    ti_success!(ti_success_unit_RecordOneKind, "unit/RecordOneKind");
-    ti_success!(ti_success_unit_RecordOneType, "unit/RecordOneType");
-    ti_success!(ti_success_unit_RecordOneValue, "unit/RecordOneValue");
-    ti_success!(ti_success_unit_RecordProjectionEmpty, "unit/RecordProjectionEmpty");
-    ti_success!(ti_success_unit_RecordProjectionKind, "unit/RecordProjectionKind");
-    ti_success!(ti_success_unit_RecordProjectionType, "unit/RecordProjectionType");
-    ti_success!(ti_success_unit_RecordProjectionValue, "unit/RecordProjectionValue");
-    ti_success!(ti_success_unit_RecordSelectionKind, "unit/RecordSelectionKind");
-    ti_success!(ti_success_unit_RecordSelectionType, "unit/RecordSelectionType");
-    ti_success!(ti_success_unit_RecordSelectionValue, "unit/RecordSelectionValue");
-    ti_success!(ti_success_unit_RecordType, "unit/RecordType");
-    ti_success!(ti_success_unit_RecordTypeEmpty, "unit/RecordTypeEmpty");
-    ti_success!(ti_success_unit_RecordTypeKind, "unit/RecordTypeKind");
-    ti_success!(ti_success_unit_RecordTypeKindLike, "unit/RecordTypeKindLike");
-    ti_success!(ti_success_unit_RecordTypeNestedKind, "unit/RecordTypeNestedKind");
-    ti_success!(ti_success_unit_RecordTypeNestedKindLike, "unit/RecordTypeNestedKindLike");
-    ti_success!(ti_success_unit_RecordTypeType, "unit/RecordTypeType");
-    ti_success!(ti_success_unit_RecursiveRecordMergeLhsEmpty, "unit/RecursiveRecordMergeLhsEmpty");
-    ti_success!(ti_success_unit_RecursiveRecordMergeRecursively, "unit/RecursiveRecordMergeRecursively");
-    ti_success!(ti_success_unit_RecursiveRecordMergeRecursivelyKinds, "unit/RecursiveRecordMergeRecursivelyKinds");
-    ti_success!(ti_success_unit_RecursiveRecordMergeRecursivelyTypes, "unit/RecursiveRecordMergeRecursivelyTypes");
-    ti_success!(ti_success_unit_RecursiveRecordMergeRhsEmpty, "unit/RecursiveRecordMergeRhsEmpty");
-    ti_success!(ti_success_unit_RecursiveRecordMergeTwo, "unit/RecursiveRecordMergeTwo");
-    ti_success!(ti_success_unit_RecursiveRecordMergeTwoKinds, "unit/RecursiveRecordMergeTwoKinds");
-    ti_success!(ti_success_unit_RecursiveRecordMergeTwoTypes, "unit/RecursiveRecordMergeTwoTypes");
-    ti_success!(ti_success_unit_RecursiveRecordTypeMergeRecursively, "unit/RecursiveRecordTypeMergeRecursively");
-    ti_success!(ti_success_unit_RecursiveRecordTypeMergeRecursivelyKinds, "unit/RecursiveRecordTypeMergeRecursivelyKinds");
-    ti_success!(ti_success_unit_RecursiveRecordTypeMergeRecursivelyTypes, "unit/RecursiveRecordTypeMergeRecursivelyTypes");
-    ti_success!(ti_success_unit_RecursiveRecordTypeMergeRhsEmpty, "unit/RecursiveRecordTypeMergeRhsEmpty");
-    ti_success!(ti_success_unit_RecursiveRecordTypeMergeTwo, "unit/RecursiveRecordTypeMergeTwo");
-    ti_success!(ti_success_unit_RecursiveRecordTypeMergeTwoKinds, "unit/RecursiveRecordTypeMergeTwoKinds");
-    ti_success!(ti_success_unit_RecursiveRecordTypeMergeTwoTypes, "unit/RecursiveRecordTypeMergeTwoTypes");
-    ti_success!(ti_success_unit_RightBiasedRecordMergeRhsEmpty, "unit/RightBiasedRecordMergeRhsEmpty");
-    ti_success!(ti_success_unit_RightBiasedRecordMergeTwo, "unit/RightBiasedRecordMergeTwo");
-    ti_success!(ti_success_unit_RightBiasedRecordMergeTwoDifferent, "unit/RightBiasedRecordMergeTwoDifferent");
-    ti_success!(ti_success_unit_RightBiasedRecordMergeTwoKinds, "unit/RightBiasedRecordMergeTwoKinds");
-    ti_success!(ti_success_unit_RightBiasedRecordMergeTwoTypes, "unit/RightBiasedRecordMergeTwoTypes");
-    ti_success!(ti_success_unit_SomeTrue, "unit/SomeTrue");
-    ti_success!(ti_success_unit_Text, "unit/Text");
-    ti_success!(ti_success_unit_TextLiteral, "unit/TextLiteral");
-    ti_success!(ti_success_unit_TextLiteralNormalizeArguments, "unit/TextLiteralNormalizeArguments");
-    ti_success!(ti_success_unit_TextLiteralWithInterpolation, "unit/TextLiteralWithInterpolation");
-    ti_success!(ti_success_unit_TextShow, "unit/TextShow");
-    ti_success!(ti_success_unit_True, "unit/True");
-    ti_success!(ti_success_unit_Type, "unit/Type");
-    ti_success!(ti_success_unit_TypeAnnotation, "unit/TypeAnnotation");
-    ti_success!(ti_success_unit_TypeAnnotationSort, "unit/TypeAnnotationSort");
-    ti_success!(ti_success_unit_UnionConstructorEmptyField, "unit/UnionConstructorEmptyField");
-    ti_success!(ti_success_unit_UnionConstructorField, "unit/UnionConstructorField");
-    ti_success!(ti_success_unit_UnionLiteralOne, "unit/UnionLiteralOne");
-    ti_success!(ti_success_unit_UnionTypeEmpty, "unit/UnionTypeEmpty");
-    ti_success!(ti_success_unit_UnionTypeKind, "unit/UnionTypeKind");
-    ti_success!(ti_success_unit_UnionTypeOne, "unit/UnionTypeOne");
-    ti_success!(ti_success_unit_UnionTypeType, "unit/UnionTypeType");
-}
diff --git a/dhall/src/tests.rs b/dhall/src/tests.rs
index 2f68dac..9784eec 100644
--- a/dhall/src/tests.rs
+++ b/dhall/src/tests.rs
@@ -45,6 +45,7 @@ pub enum Feature {
     Parser,
     Printer,
     BinaryEncoding,
+    BinaryDecoding,
     Import,
     Normalization,
     AlphaNormalization,
@@ -80,20 +81,27 @@ pub fn run_test(
 ) -> Result<()> {
     use self::Feature::*;
     use self::Status::*;
-    let feature_prefix = match feature {
-        Parser => "parser/",
-        Printer => "parser/",
-        BinaryEncoding => "parser/",
-        Import => "import/",
-        Normalization => "normalization/",
-        AlphaNormalization => "alpha-normalization/",
-        Typecheck => "typecheck/",
-        TypeInference => "type-inference/",
-    };
-    let base_path =
-        "../dhall-lang/tests/".to_owned() + feature_prefix + base_path;
+    let base_path = base_path.to_owned();
     match status {
         Success => {
+            match feature {
+                BinaryDecoding => {
+                    let expr_file_path = base_path.clone() + "A.dhallb";
+                    let expr_file_path = PathBuf::from(&expr_file_path);
+                    let mut expr_data = Vec::new();
+                    {
+                        File::open(&expr_file_path)?
+                            .read_to_end(&mut expr_data)?;
+                    }
+                    let expr = Parsed::parse_binary(&expr_data)?;
+                    let expected_file_path = base_path + "B.dhall";
+                    let expected = parse_file_str(&expected_file_path)?;
+                    assert_eq_pretty!(expr, expected);
+
+                    return Ok(());
+                }
+                _ => {}
+            }
             let expr_file_path = base_path.clone() + "A.dhall";
             let expr = parse_file_str(&expr_file_path)?;
 
@@ -164,7 +172,9 @@ pub fn run_test(
                 .normalize();
 
             match feature {
-                Parser | Printer | BinaryEncoding => unreachable!(),
+                Parser | Printer | BinaryEncoding | BinaryDecoding => {
+                    unreachable!()
+                }
                 Import => {
                     let expr = expr.skip_typecheck().normalize();
                     assert_eq_display!(expr, expected);
@@ -195,10 +205,21 @@ pub fn run_test(
                     let err = parse_file_str(&file_path).unwrap_err();
                     match err {
                         Error::Parse(_) => {}
+                        Error::IO(e)
+                            if e.kind() == std::io::ErrorKind::InvalidData => {}
                         e => panic!("Expected parse error, got: {:?}", e),
                     }
                 }
                 Printer | BinaryEncoding => unreachable!(),
+                BinaryDecoding => {
+                    let expr_file_path = file_path + "b";
+                    let mut expr_data = Vec::new();
+                    {
+                        File::open(&PathBuf::from(&expr_file_path))?
+                            .read_to_end(&mut expr_data)?;
+                    }
+                    Parsed::parse_binary(&expr_data).unwrap_err();
+                }
                 Import => {
                     parse_file_str(&file_path)?.resolve().unwrap_err();
                 }