Merge pull request #154 from Nadrieril/cleanup-api

Rewrite serde_dhall API

32 files changed, 318 insertions, 477 deletions

diff --git a/dhall/Cargo.toml b/dhall/Cargo.toml
index 0ffe78b..bb60d9e 100644
--- a/dhall/Cargo.toml
+++ b/dhall/Cargo.toml
@@ -22,10 +22,11 @@ reqwest = { version = "0.10", features = ["blocking"] }
 serde = "1.0"
 serde_cbor = "0.9.0"
 smallvec = "1.0.0"
-url = "2.1.1"
+url = "2.1"
 
 [dev-dependencies]
 pretty_assertions = "0.6.1"
+version-sync = "0.8"
 
 [build-dependencies]
 walkdir = "2"
diff --git a/dhall/README.md b/dhall/README.md
index 82b3e6a..25f11f7 100644
--- a/dhall/README.md
+++ b/dhall/README.md
@@ -1,10 +1,11 @@
 # `dhall`
 
 Implementation of the Dhall configuration language.
-This is an internal crate used for [`serde_dhall`], you probably want to use
-that instead.
 
-The API is very unstable and does not respect semver;
-use at your own risk.
+WARNING: This is an internal crate used for [`serde_dhall`], you probably want
+to use that instead.
+
+WARNING: The API is very unstable and does not respect semver; use at your own
+risk.
 
 [`serde_dhall`]: https://docs.rs/serde_dhall
diff --git a/dhall/src/error/builder.rs b/dhall/src/error/builder.rs
index c0bacb5..3ee65fb 100644
--- a/dhall/src/error/builder.rs
+++ b/dhall/src/error/builder.rs
@@ -6,7 +6,7 @@ use annotate_snippets::{
 use crate::syntax::{ParsedSpan, Span};
 
 #[derive(Debug, Clone, Default)]
-pub(crate) struct ErrorBuilder {
+pub struct ErrorBuilder {
     title: FreeAnnotation,
     annotations: Vec<SpannedAnnotation>,
     footer: Vec<FreeAnnotation>,
diff --git a/dhall/src/error/mod.rs b/dhall/src/error/mod.rs
index e28b98b..ef4d41f 100644
--- a/dhall/src/error/mod.rs
+++ b/dhall/src/error/mod.rs
@@ -4,7 +4,7 @@ use crate::semantics::resolve::{ImportLocation, ImportStack};
 use crate::syntax::{Import, ParseError};
 
 mod builder;
-pub(crate) use builder::*;
+pub use builder::*;
 
 pub type Result<T> = std::result::Result<T, Error>;
 
@@ -15,7 +15,7 @@ pub struct Error {
 
 #[derive(Debug)]
 #[non_exhaustive]
-pub(crate) enum ErrorKind {
+pub enum ErrorKind {
     IO(IOError),
     Parse(ParseError),
     Decode(DecodeError),
@@ -25,7 +25,7 @@ pub(crate) enum ErrorKind {
 }
 
 #[derive(Debug)]
-pub(crate) enum ImportError {
+pub enum ImportError {
     Missing,
     MissingEnvVar,
     SanityCheck,
@@ -53,21 +53,21 @@ pub struct TypeError {
 
 /// The specific type error
 #[derive(Debug)]
-pub(crate) enum TypeMessage {
+pub enum TypeMessage {
     Custom(String),
 }
 
 impl Error {
-    pub(crate) fn new(kind: ErrorKind) -> Self {
+    pub fn new(kind: ErrorKind) -> Self {
         Error { kind }
     }
-    pub(crate) fn kind(&self) -> &ErrorKind {
+    pub fn kind(&self) -> &ErrorKind {
         &self.kind
     }
 }
 
 impl TypeError {
-    pub(crate) fn new(message: TypeMessage) -> Self {
+    pub fn new(message: TypeMessage) -> Self {
         TypeError { message }
     }
 }
diff --git a/dhall/src/lib.rs b/dhall/src/lib.rs
index 24e4377..392c344 100644
--- a/dhall/src/lib.rs
+++ b/dhall/src/lib.rs
@@ -1,7 +1,10 @@
 #![doc(html_root_url = "https://docs.rs/dhall/0.4.0")]
 #![allow(
+    clippy::implicit_hasher,
     clippy::module_inception,
     clippy::needless_lifetimes,
+    clippy::new_ret_no_self,
+    clippy::new_without_default,
     clippy::useless_format
 )]
 
@@ -15,23 +18,15 @@ use std::fmt::Display;
 use std::path::Path;
 use url::Url;
 
-use crate::error::{EncodeError, Error, TypeError};
+use crate::error::{Error, TypeError};
 use crate::semantics::parse;
 use crate::semantics::resolve;
 use crate::semantics::resolve::ImportLocation;
-use crate::semantics::{
-    typecheck, typecheck_with, Hir, Nir, NirKind, Tir, Type,
-};
-use crate::syntax::binary;
-use crate::syntax::{Builtin, Expr};
-
-pub type ParsedExpr = Expr;
-pub type DecodedExpr = Expr;
-pub type ResolvedExpr = Expr;
-pub type NormalizedExpr = Expr;
+use crate::semantics::{typecheck, typecheck_with, Hir, Nir, Tir, Type};
+use crate::syntax::Expr;
 
 #[derive(Debug, Clone)]
-pub struct Parsed(ParsedExpr, ImportLocation);
+pub struct Parsed(Expr, ImportLocation);
 
 /// An expression where all imports have been resolved
 ///
@@ -48,15 +43,15 @@ pub struct Typed {
 
 /// A normalized expression.
 ///
-/// Invariant: the contained expression must be in normal form,
+/// This is actually a lie, because the expression will only get normalized on demand.
 #[derive(Debug, Clone)]
 pub struct Normalized(Nir);
 
 /// Controls conversion from `Nir` to `Expr`
-#[derive(Copy, Clone)]
-pub(crate) struct ToExprOptions {
+#[derive(Copy, Clone, Default)]
+pub struct ToExprOptions {
     /// Whether to convert all variables to `_`
-    pub(crate) alpha: bool,
+    pub alpha: bool,
 }
 
 impl Parsed {
@@ -72,6 +67,7 @@ impl Parsed {
     pub fn parse_binary_file(f: &Path) -> Result<Parsed, Error> {
         parse::parse_binary_file(f)
     }
+    #[allow(dead_code)]
     pub fn parse_binary(data: &[u8]) -> Result<Parsed, Error> {
         parse::parse_binary(data)
     }
@@ -80,15 +76,11 @@ impl Parsed {
         resolve::resolve(self)
     }
     pub fn skip_resolve(self) -> Result<Resolved, Error> {
-        Ok(Resolved(resolve::skip_resolve(&self.0)?))
-    }
-
-    pub fn encode(&self) -> Result<Vec<u8>, EncodeError> {
-        binary::encode(&self.0)
+        resolve::skip_resolve(self)
     }
 
     /// Converts a value back to the corresponding AST expression.
-    pub fn to_expr(&self) -> ParsedExpr {
+    pub fn to_expr(&self) -> Expr {
         self.0.clone()
     }
 }
@@ -97,11 +89,11 @@ 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 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 {
+    pub fn to_expr(&self) -> Expr {
         self.0.to_expr_noopts()
     }
 }
@@ -115,79 +107,38 @@ impl Typed {
     }
     /// Reduce an expression to its normal form, performing beta reduction
     pub fn normalize(&self) -> Normalized {
-        Normalized(self.hir.rec_eval_closed_expr())
+        Normalized(self.hir.eval_closed_expr())
     }
 
     /// Converts a value back to the corresponding AST expression.
-    fn to_expr(&self) -> ResolvedExpr {
+    fn to_expr(&self) -> Expr {
         self.hir.to_expr(ToExprOptions { alpha: false })
     }
 
-    pub(crate) fn ty(&self) -> &Type {
+    pub fn ty(&self) -> &Type {
         &self.ty
     }
-    pub(crate) fn get_type(&self) -> Result<Normalized, TypeError> {
+    pub fn get_type(&self) -> Result<Normalized, TypeError> {
         Ok(Normalized(self.ty.clone().into_nir()))
     }
 }
 
 impl Normalized {
-    pub fn encode(&self) -> Result<Vec<u8>, EncodeError> {
-        binary::encode(&self.to_expr())
-    }
-
     /// Converts a value back to the corresponding AST expression.
-    pub fn to_expr(&self) -> NormalizedExpr {
-        self.0.to_expr(ToExprOptions { alpha: false })
+    pub fn to_expr(&self) -> Expr {
+        self.0.to_expr(ToExprOptions::default())
     }
     /// Converts a value back to the corresponding Hir expression.
-    pub(crate) fn to_hir(&self) -> Hir {
+    pub fn to_hir(&self) -> Hir {
         self.0.to_hir_noenv()
     }
+    pub fn as_nir(&self) -> &Nir {
+        &self.0
+    }
     /// Converts a value back to the corresponding AST expression, alpha-normalizing in the process.
-    pub(crate) fn to_expr_alpha(&self) -> NormalizedExpr {
+    pub fn to_expr_alpha(&self) -> Expr {
         self.0.to_expr(ToExprOptions { alpha: true })
     }
-    pub(crate) fn to_nir(&self) -> Nir {
-        self.0.clone()
-    }
-    pub(crate) fn into_nir(self) -> Nir {
-        self.0
-    }
-
-    pub(crate) fn from_kind(v: NirKind) -> Self {
-        Normalized(Nir::from_kind(v))
-    }
-    pub(crate) fn from_nir(th: Nir) -> Self {
-        Normalized(th)
-    }
-
-    pub fn make_builtin_type(b: Builtin) -> Self {
-        Normalized::from_nir(Nir::from_builtin(b))
-    }
-    pub fn make_optional_type(t: Normalized) -> Self {
-        Normalized::from_nir(
-            Nir::from_builtin(Builtin::Optional).app(t.to_nir()),
-        )
-    }
-    pub fn make_list_type(t: Normalized) -> Self {
-        Normalized::from_nir(Nir::from_builtin(Builtin::List).app(t.to_nir()))
-    }
-    pub fn make_record_type(
-        kts: impl Iterator<Item = (String, Normalized)>,
-    ) -> Self {
-        Normalized::from_kind(NirKind::RecordType(
-            kts.map(|(k, t)| (k.into(), t.into_nir())).collect(),
-        ))
-    }
-    pub fn make_union_type(
-        kts: impl Iterator<Item = (String, Option<Normalized>)>,
-    ) -> Self {
-        Normalized::from_kind(NirKind::UnionType(
-            kts.map(|(k, t)| (k.into(), t.map(|t| t.into_nir())))
-                .collect(),
-        ))
-    }
 }
 
 macro_rules! derive_traits_for_wrapper_struct {
@@ -213,23 +164,12 @@ macro_rules! derive_traits_for_wrapper_struct {
 
 derive_traits_for_wrapper_struct!(Parsed);
 
-impl std::hash::Hash for Normalized {
-    fn hash<H>(&self, state: &mut H)
-    where
-        H: std::hash::Hasher,
-    {
-        if let Ok(vec) = self.encode() {
-            vec.hash(state)
-        }
-    }
-}
-
-impl From<Parsed> for NormalizedExpr {
+impl From<Parsed> for Expr {
     fn from(other: Parsed) -> Self {
         other.to_expr()
     }
 }
-impl From<Normalized> for NormalizedExpr {
+impl From<Normalized> for Expr {
     fn from(other: Normalized) -> Self {
         other.to_expr()
     }
diff --git a/dhall/src/semantics/builtins.rs b/dhall/src/semantics/builtins.rs
index 803630b..6007a92 100644
--- a/dhall/src/semantics/builtins.rs
+++ b/dhall/src/semantics/builtins.rs
@@ -1,48 +1,35 @@
 use crate::semantics::{
-    skip_resolve, typecheck, Hir, HirKind, Nir, NirKind, NzEnv, VarEnv,
+    skip_resolve_expr, typecheck, Hir, HirKind, Nir, NirKind, NzEnv, VarEnv,
 };
 use crate::syntax::map::DupTreeMap;
 use crate::syntax::Const::Type;
 use crate::syntax::{
     BinOp, Builtin, Const, Expr, ExprKind, InterpolatedText,
-    InterpolatedTextContents, Label, LitKind, NaiveDouble, Span, UnspannedExpr,
+    InterpolatedTextContents, Label, NaiveDouble, NumKind, Span, UnspannedExpr,
     V,
 };
-use crate::Normalized;
 use std::collections::HashMap;
 use std::convert::TryInto;
 
 /// A partially applied builtin.
 /// Invariant: the evaluation of the given args must not be able to progress further
 #[derive(Debug, Clone)]
-pub(crate) struct BuiltinClosure<Nir> {
-    pub env: NzEnv,
-    pub b: Builtin,
+pub struct BuiltinClosure {
+    env: NzEnv,
+    b: Builtin,
     /// Arguments applied to the closure so far.
-    pub args: Vec<Nir>,
+    args: Vec<Nir>,
 }
 
-impl BuiltinClosure<Nir> {
-    pub fn new(b: Builtin, env: NzEnv) -> Self {
-        BuiltinClosure {
-            env,
-            b,
-            args: Vec::new(),
-        }
+impl BuiltinClosure {
+    pub fn new(b: Builtin, env: NzEnv) -> NirKind {
+        apply_builtin(b, Vec::new(), env)
     }
-
     pub fn apply(&self, a: Nir) -> NirKind {
         use std::iter::once;
         let args = self.args.iter().cloned().chain(once(a)).collect();
         apply_builtin(self.b, args, self.env.clone())
     }
-    /// This doesn't break the invariant because we already checked that the appropriate arguments
-    /// did not normalize to something that allows evaluation to proceed.
-    pub fn normalize(&self) {
-        for x in self.args.iter() {
-            x.normalize();
-        }
-    }
     pub fn to_hirkind(&self, venv: VarEnv) -> HirKind {
         HirKind::Expr(self.args.iter().fold(
             ExprKind::Builtin(self.b),
@@ -56,7 +43,7 @@ impl BuiltinClosure<Nir> {
     }
 }
 
-pub(crate) fn rc(x: UnspannedExpr) -> Expr {
+pub fn rc(x: UnspannedExpr) -> Expr {
     Expr::new(x, Span::Artificial)
 }
 
@@ -116,7 +103,7 @@ macro_rules! make_type {
     };
 }
 
-pub(crate) fn type_of_builtin(b: Builtin) -> Hir {
+pub fn type_of_builtin(b: Builtin) -> Hir {
     use Builtin::*;
     let expr = match b {
         Bool | Natural | Integer | Double | Text => make_type!(Type),
@@ -202,7 +189,7 @@ pub(crate) fn type_of_builtin(b: Builtin) -> Hir {
             forall (A: Type) -> Optional A
         ),
     };
-    skip_resolve(&expr).unwrap()
+    skip_resolve_expr(&expr).unwrap()
 }
 
 // Ad-hoc macro to help construct closures
@@ -241,7 +228,7 @@ macro_rules! make_closure {
         rc(ExprKind::BinOp(
             BinOp::NaturalPlus,
             make_closure!($($v)*),
-            rc(ExprKind::Lit(LitKind::Natural(1)))
+            rc(ExprKind::Num(NumKind::Natural(1)))
         ))
     };
     ([ $($head:tt)* ] # $($tail:tt)*) => {{
@@ -257,8 +244,8 @@ macro_rules! make_closure {
 
 #[allow(clippy::cognitive_complexity)]
 fn apply_builtin(b: Builtin, args: Vec<Nir>, env: NzEnv) -> NirKind {
-    use LitKind::{Bool, Double, Integer, Natural};
     use NirKind::*;
+    use NumKind::{Bool, Double, Integer, Natural};
 
     // Small helper enum
     enum Ret {
@@ -267,46 +254,54 @@ fn apply_builtin(b: Builtin, args: Vec<Nir>, env: NzEnv) -> NirKind {
         DoneAsIs,
     }
     let make_closure = |e| {
-        typecheck(&skip_resolve(&e).unwrap())
+        typecheck(&skip_resolve_expr(&e).unwrap())
             .unwrap()
             .eval(env.clone())
     };
 
     let ret = match (b, args.as_slice()) {
+        (Builtin::Bool, [])
+        | (Builtin::Natural, [])
+        | (Builtin::Integer, [])
+        | (Builtin::Double, [])
+        | (Builtin::Text, []) => Ret::NirKind(BuiltinType(b)),
+        (Builtin::Optional, [t]) => Ret::NirKind(OptionalType(t.clone())),
+        (Builtin::List, [t]) => Ret::NirKind(ListType(t.clone())),
+
         (Builtin::OptionalNone, [t]) => {
             Ret::NirKind(EmptyOptionalLit(t.clone()))
         }
         (Builtin::NaturalIsZero, [n]) => match &*n.kind() {
-            Lit(Natural(n)) => Ret::NirKind(Lit(Bool(*n == 0))),
+            Num(Natural(n)) => Ret::NirKind(Num(Bool(*n == 0))),
             _ => Ret::DoneAsIs,
         },
         (Builtin::NaturalEven, [n]) => match &*n.kind() {
-            Lit(Natural(n)) => Ret::NirKind(Lit(Bool(*n % 2 == 0))),
+            Num(Natural(n)) => Ret::NirKind(Num(Bool(*n % 2 == 0))),
             _ => Ret::DoneAsIs,
         },
         (Builtin::NaturalOdd, [n]) => match &*n.kind() {
-            Lit(Natural(n)) => Ret::NirKind(Lit(Bool(*n % 2 != 0))),
+            Num(Natural(n)) => Ret::NirKind(Num(Bool(*n % 2 != 0))),
             _ => Ret::DoneAsIs,
         },
         (Builtin::NaturalToInteger, [n]) => match &*n.kind() {
-            Lit(Natural(n)) => Ret::NirKind(Lit(Integer(*n as isize))),
+            Num(Natural(n)) => Ret::NirKind(Num(Integer(*n as isize))),
             _ => Ret::DoneAsIs,
         },
         (Builtin::NaturalShow, [n]) => match &*n.kind() {
-            Lit(Natural(n)) => Ret::Nir(Nir::from_text(n)),
+            Num(Natural(n)) => Ret::Nir(Nir::from_text(n)),
             _ => Ret::DoneAsIs,
         },
         (Builtin::NaturalSubtract, [a, b]) => match (&*a.kind(), &*b.kind()) {
-            (Lit(Natural(a)), Lit(Natural(b))) => {
-                Ret::NirKind(Lit(Natural(if b > a { b - a } else { 0 })))
+            (Num(Natural(a)), Num(Natural(b))) => {
+                Ret::NirKind(Num(Natural(if b > a { b - a } else { 0 })))
             }
-            (Lit(Natural(0)), _) => Ret::Nir(b.clone()),
-            (_, Lit(Natural(0))) => Ret::NirKind(Lit(Natural(0))),
-            _ if a == b => Ret::NirKind(Lit(Natural(0))),
+            (Num(Natural(0)), _) => Ret::Nir(b.clone()),
+            (_, Num(Natural(0))) => Ret::NirKind(Num(Natural(0))),
+            _ if a == b => Ret::NirKind(Num(Natural(0))),
             _ => Ret::DoneAsIs,
         },
         (Builtin::IntegerShow, [n]) => match &*n.kind() {
-            Lit(Integer(n)) => {
+            Num(Integer(n)) => {
                 let s = if *n < 0 {
                     n.to_string()
                 } else {
@@ -317,30 +312,30 @@ fn apply_builtin(b: Builtin, args: Vec<Nir>, env: NzEnv) -> NirKind {
             _ => Ret::DoneAsIs,
         },
         (Builtin::IntegerToDouble, [n]) => match &*n.kind() {
-            Lit(Integer(n)) => {
-                Ret::NirKind(Lit(Double(NaiveDouble::from(*n as f64))))
+            Num(Integer(n)) => {
+                Ret::NirKind(Num(Double(NaiveDouble::from(*n as f64))))
             }
             _ => Ret::DoneAsIs,
         },
         (Builtin::IntegerNegate, [n]) => match &*n.kind() {
-            Lit(Integer(n)) => Ret::NirKind(Lit(Integer(-n))),
+            Num(Integer(n)) => Ret::NirKind(Num(Integer(-n))),
             _ => Ret::DoneAsIs,
         },
         (Builtin::IntegerClamp, [n]) => match &*n.kind() {
-            Lit(Integer(n)) => {
-                Ret::NirKind(Lit(Natural((*n).try_into().unwrap_or(0))))
+            Num(Integer(n)) => {
+                Ret::NirKind(Num(Natural((*n).try_into().unwrap_or(0))))
             }
             _ => Ret::DoneAsIs,
         },
         (Builtin::DoubleShow, [n]) => match &*n.kind() {
-            Lit(Double(n)) => Ret::Nir(Nir::from_text(n)),
+            Num(Double(n)) => Ret::Nir(Nir::from_text(n)),
             _ => Ret::DoneAsIs,
         },
         (Builtin::TextShow, [v]) => match &*v.kind() {
             TextLit(tlit) => {
                 if let Some(s) = tlit.as_text() {
                     // Printing InterpolatedText takes care of all the escaping
-                    let txt: InterpolatedText<Normalized> =
+                    let txt: InterpolatedText<Expr> =
                         std::iter::once(InterpolatedTextContents::Text(s))
                             .collect();
                     Ret::Nir(Nir::from_text(txt))
@@ -351,8 +346,8 @@ fn apply_builtin(b: Builtin, args: Vec<Nir>, env: NzEnv) -> NirKind {
             _ => Ret::DoneAsIs,
         },
         (Builtin::ListLength, [_, l]) => match &*l.kind() {
-            EmptyListLit(_) => Ret::NirKind(Lit(Natural(0))),
-            NEListLit(xs) => Ret::NirKind(Lit(Natural(xs.len()))),
+            EmptyListLit(_) => Ret::NirKind(Num(Natural(0))),
+            NEListLit(xs) => Ret::NirKind(Num(Natural(xs.len()))),
             _ => Ret::DoneAsIs,
         },
         (Builtin::ListHead, [_, l]) => match &*l.kind() {
@@ -398,7 +393,7 @@ fn apply_builtin(b: Builtin, args: Vec<Nir>, env: NzEnv) -> NirKind {
                                     let mut kvs = HashMap::new();
                                     kvs.insert(
                                         "index".into(),
-                                        Nir::from_kind(Lit(Natural(i))),
+                                        Nir::from_kind(Num(Natural(i))),
                                     );
                                     kvs.insert("value".into(), e.clone());
                                     Nir::from_kind(RecordLit(kvs))
@@ -466,14 +461,14 @@ fn apply_builtin(b: Builtin, args: Vec<Nir>, env: NzEnv) -> NirKind {
                     λ(x : Natural) ->
                     1 + var(x)
                 )))
-                .app(Lit(Natural(0)).into_nir()),
+                .app(Num(Natural(0)).into_nir()),
         ),
 
         (Builtin::NaturalFold, [n, t, succ, zero]) => match &*n.kind() {
-            Lit(Natural(0)) => Ret::Nir(zero.clone()),
-            Lit(Natural(n)) => {
+            Num(Natural(0)) => Ret::Nir(zero.clone()),
+            Num(Natural(n)) => {
                 let fold = Nir::from_builtin(Builtin::NaturalFold)
-                    .app(Lit(Natural(n - 1)).into_nir())
+                    .app(Num(Natural(n - 1)).into_nir())
                     .app(t.clone())
                     .app(succ.clone())
                     .app(zero.clone());
@@ -490,9 +485,9 @@ fn apply_builtin(b: Builtin, args: Vec<Nir>, env: NzEnv) -> NirKind {
     }
 }
 
-impl<Nir: std::cmp::PartialEq> std::cmp::PartialEq for BuiltinClosure<Nir> {
+impl std::cmp::PartialEq for BuiltinClosure {
     fn eq(&self, other: &Self) -> bool {
         self.b == other.b && self.args == other.args
     }
 }
-impl<Nir: std::cmp::Eq> std::cmp::Eq for BuiltinClosure<Nir> {}
+impl std::cmp::Eq for BuiltinClosure {}
diff --git a/dhall/src/semantics/mod.rs b/dhall/src/semantics/mod.rs
index 87033c9..468d8b1 100644
--- a/dhall/src/semantics/mod.rs
+++ b/dhall/src/semantics/mod.rs
@@ -3,7 +3,7 @@ pub mod nze;
 pub mod parse;
 pub mod resolve;
 pub mod tck;
-pub(crate) use self::builtins::*;
-pub(crate) use self::nze::*;
-pub(crate) use self::resolve::*;
-pub(crate) use self::tck::*;
+pub use self::builtins::*;
+pub use self::nze::*;
+pub use self::resolve::*;
+pub use self::tck::*;
diff --git a/dhall/src/semantics/nze/env.rs b/dhall/src/semantics/nze/env.rs
index ef2bee6..ec99dbe 100644
--- a/dhall/src/semantics/nze/env.rs
+++ b/dhall/src/semantics/nze/env.rs
@@ -1,7 +1,7 @@
 use crate::semantics::{AlphaVar, Nir, NirKind};
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub(crate) enum NzVar {
+pub enum NzVar {
     /// Reverse-debruijn index: counts number of binders from the bottom of the stack.
     Bound(usize),
     /// Fake fresh variable generated for expression equality checking.
@@ -17,11 +17,11 @@ enum EnvItem<Type> {
 }
 
 #[derive(Debug, Clone)]
-pub(crate) struct ValEnv<Type> {
+pub struct ValEnv<Type> {
     items: Vec<EnvItem<Type>>,
 }
 
-pub(crate) type NzEnv = ValEnv<()>;
+pub type NzEnv = ValEnv<()>;
 
 impl NzVar {
     pub fn new(idx: usize) -> Self {
diff --git a/dhall/src/semantics/nze/mod.rs b/dhall/src/semantics/nze/mod.rs
index 2648339..23022e0 100644
--- a/dhall/src/semantics/nze/mod.rs
+++ b/dhall/src/semantics/nze/mod.rs
@@ -3,7 +3,7 @@ pub mod lazy;
 pub mod nir;
 pub mod normalize;
 pub mod var;
-pub(crate) use env::*;
-pub(crate) use nir::*;
-pub(crate) use normalize::*;
-pub(crate) use var::*;
+pub use env::*;
+pub use nir::*;
+pub use normalize::*;
+pub use var::*;
diff --git a/dhall/src/semantics/nze/nir.rs b/dhall/src/semantics/nze/nir.rs
index 32ef590..e0d227e 100644
--- a/dhall/src/semantics/nze/nir.rs
+++ b/dhall/src/semantics/nze/nir.rs
@@ -7,10 +7,10 @@ use crate::semantics::{
     BuiltinClosure, Hir, HirKind, NzEnv, NzVar, TyEnv, Type, Universe, VarEnv,
 };
 use crate::syntax::{
-    BinOp, Builtin, Const, ExprKind, InterpolatedTextContents, Label, LitKind,
-    Span,
+    BinOp, Builtin, Const, Expr, ExprKind, InterpolatedTextContents, Label,
+    NumKind, Span,
 };
-use crate::{NormalizedExpr, ToExprOptions};
+use crate::ToExprOptions;
 
 /// Stores a possibly unevaluated value. Gets (partially) normalized on-demand, sharing computation
 /// automatically. Uses a Rc<RefCell> to share computation.
@@ -19,7 +19,7 @@ use crate::{NormalizedExpr, ToExprOptions};
 /// normalize as needed.
 /// Stands for "Normalized intermediate representation"
 #[derive(Clone)]
-pub(crate) struct Nir(Rc<NirInternal>);
+pub struct Nir(Rc<NirInternal>);
 
 #[derive(Debug)]
 struct NirInternal {
@@ -28,7 +28,7 @@ struct NirInternal {
 
 /// An unevaluated subexpression
 #[derive(Debug, Clone)]
-pub(crate) enum Thunk {
+pub enum Thunk {
     /// A completely unnormalized expression.
     Thunk { env: NzEnv, body: Hir },
     /// A partially normalized expression that may need to go through `normalize_one_layer`.
@@ -37,7 +37,7 @@ pub(crate) enum Thunk {
 
 /// An unevaluated subexpression that takes an argument.
 #[derive(Debug, Clone)]
-pub(crate) enum Closure {
+pub enum Closure {
     /// Normal closure
     Closure { env: NzEnv, body: Hir },
     /// Closure that ignores the argument passed
@@ -48,7 +48,7 @@ pub(crate) enum Closure {
 // Invariant: this must not contain interpolations that are themselves TextLits, and contiguous
 // text values must be merged.
 #[derive(Debug, Clone, PartialEq, Eq)]
-pub(crate) struct TextLit(Vec<InterpolatedTextContents<Nir>>);
+pub struct TextLit(Vec<InterpolatedTextContents<Nir>>);
 
 /// This represents a value in Weak Head Normal Form (WHNF). This means that the value is
 /// normalized up to the first constructor, but subexpressions may not be fully normalized.
@@ -58,7 +58,7 @@ pub(crate) struct TextLit(Vec<InterpolatedTextContents<Nir>>);
 /// In particular, this means that once we get a `NirKind`, it can be considered immutable, and
 /// we only need to recursively normalize its sub-`Nir`s to get to the NF.
 #[derive(Debug, Clone, PartialEq, Eq)]
-pub(crate) enum NirKind {
+pub enum NirKind {
     /// Closures
     LamClosure {
         binder: Binder,
@@ -70,13 +70,17 @@ pub(crate) enum NirKind {
         annot: Nir,
         closure: Closure,
     },
-    AppliedBuiltin(BuiltinClosure<Nir>),
+    AppliedBuiltin(BuiltinClosure),
 
     Var(NzVar),
     Const(Const),
-    Lit(LitKind),
+    // Must be a number type, Bool or Text
+    BuiltinType(Builtin),
+    Num(NumKind),
+    OptionalType(Nir),
     EmptyOptionalLit(Nir),
     NEOptionalLit(Nir),
+    ListType(Nir),
     // EmptyListLit(t) means `[] : List t`, not `[] : t`
     EmptyListLit(Nir),
     NEListLit(Vec<Nir>),
@@ -93,34 +97,34 @@ pub(crate) enum NirKind {
 
 impl Nir {
     /// Construct a Nir from a completely unnormalized expression.
-    pub(crate) fn new_thunk(env: NzEnv, hir: Hir) -> Nir {
+    pub fn new_thunk(env: NzEnv, hir: Hir) -> Nir {
         NirInternal::from_thunk(Thunk::new(env, hir)).into_nir()
     }
     /// Construct a Nir from a partially normalized expression that's not in WHNF.
-    pub(crate) fn from_partial_expr(e: ExprKind<Nir>) -> Nir {
+    pub fn from_partial_expr(e: ExprKind<Nir>) -> Nir {
         // TODO: env
         let env = NzEnv::new();
         NirInternal::from_thunk(Thunk::from_partial_expr(env, e)).into_nir()
     }
     /// Make a Nir from a NirKind
-    pub(crate) fn from_kind(v: NirKind) -> Nir {
+    pub fn from_kind(v: NirKind) -> Nir {
         NirInternal::from_whnf(v).into_nir()
     }
-    pub(crate) fn from_const(c: Const) -> Self {
+    pub fn from_const(c: Const) -> Self {
         let v = NirKind::Const(c);
         NirInternal::from_whnf(v).into_nir()
     }
-    pub(crate) fn from_builtin(b: Builtin) -> Self {
+    pub fn from_builtin(b: Builtin) -> Self {
         Self::from_builtin_env(b, &NzEnv::new())
     }
-    pub(crate) fn from_builtin_env(b: Builtin, env: &NzEnv) -> Self {
+    pub fn from_builtin_env(b: Builtin, env: &NzEnv) -> Self {
         Nir::from_kind(NirKind::from_builtin_env(b, env.clone()))
     }
-    pub(crate) fn from_text(txt: impl ToString) -> Self {
+    pub fn from_text(txt: impl ToString) -> Self {
         Nir::from_kind(NirKind::TextLit(TextLit::from_text(txt.to_string())))
     }
 
-    pub(crate) fn as_const(&self) -> Option<Const> {
+    pub fn as_const(&self) -> Option<Const> {
         match &*self.kind() {
             NirKind::Const(c) => Some(*c),
             _ => None,
@@ -128,26 +132,22 @@ impl Nir {
     }
 
     /// This is what you want if you want to pattern-match on the value.
-    pub(crate) fn kind(&self) -> &NirKind {
+    pub fn kind(&self) -> &NirKind {
         self.0.kind()
     }
 
-    pub(crate) fn to_type(&self, u: impl Into<Universe>) -> Type {
+    pub fn to_type(&self, u: impl Into<Universe>) -> Type {
         Type::new(self.clone(), u.into())
     }
     /// Converts a value back to the corresponding AST expression.
-    pub(crate) fn to_expr(&self, opts: ToExprOptions) -> NormalizedExpr {
+    pub fn to_expr(&self, opts: ToExprOptions) -> Expr {
         self.to_hir_noenv().to_expr(opts)
     }
-    pub(crate) fn to_expr_tyenv(&self, tyenv: &TyEnv) -> NormalizedExpr {
+    pub fn to_expr_tyenv(&self, tyenv: &TyEnv) -> Expr {
         self.to_hir(tyenv.as_varenv()).to_expr_tyenv(tyenv)
     }
 
-    pub(crate) fn normalize(&self) {
-        self.0.normalize()
-    }
-
-    pub(crate) fn app(&self, v: Nir) -> Nir {
+    pub fn app(&self, v: Nir) -> Nir {
         Nir::from_kind(apply_any(self.clone(), v))
     }
 
@@ -188,12 +188,21 @@ impl Nir {
                     closure.to_hir(venv),
                 ),
                 NirKind::Const(c) => ExprKind::Const(*c),
-                NirKind::Lit(l) => ExprKind::Lit(l.clone()),
+                NirKind::BuiltinType(b) => ExprKind::Builtin(*b),
+                NirKind::Num(l) => ExprKind::Num(l.clone()),
+                NirKind::OptionalType(t) => ExprKind::App(
+                    Nir::from_builtin(Builtin::Optional).to_hir(venv),
+                    t.to_hir(venv),
+                ),
                 NirKind::EmptyOptionalLit(n) => ExprKind::App(
                     Nir::from_builtin(Builtin::OptionalNone).to_hir(venv),
                     n.to_hir(venv),
                 ),
                 NirKind::NEOptionalLit(n) => ExprKind::SomeLit(n.to_hir(venv)),
+                NirKind::ListType(t) => ExprKind::App(
+                    Nir::from_builtin(Builtin::List).to_hir(venv),
+                    t.to_hir(venv),
+                ),
                 NirKind::EmptyListLit(n) => ExprKind::EmptyListLit(Hir::new(
                     HirKind::Expr(ExprKind::App(
                         Nir::from_builtin(Builtin::List).to_hir(venv),
@@ -274,75 +283,18 @@ impl NirInternal {
     fn kind(&self) -> &NirKind {
         &self.kind
     }
-    fn normalize(&self) {
-        self.kind().normalize();
-    }
 }
 
 impl NirKind {
-    pub(crate) fn into_nir(self) -> Nir {
+    pub fn into_nir(self) -> Nir {
         Nir::from_kind(self)
     }
 
-    pub(crate) fn normalize(&self) {
-        match self {
-            NirKind::Var(..) | NirKind::Const(_) | NirKind::Lit(_) => {}
-
-            NirKind::EmptyOptionalLit(tth) | NirKind::EmptyListLit(tth) => {
-                tth.normalize();
-            }
-
-            NirKind::NEOptionalLit(th) => {
-                th.normalize();
-            }
-            NirKind::LamClosure { annot, closure, .. }
-            | NirKind::PiClosure { annot, closure, .. } => {
-                annot.normalize();
-                closure.normalize();
-            }
-            NirKind::AppliedBuiltin(closure) => closure.normalize(),
-            NirKind::NEListLit(elts) => {
-                for x in elts.iter() {
-                    x.normalize();
-                }
-            }
-            NirKind::RecordLit(kvs) => {
-                for x in kvs.values() {
-                    x.normalize();
-                }
-            }
-            NirKind::RecordType(kvs) => {
-                for x in kvs.values() {
-                    x.normalize();
-                }
-            }
-            NirKind::UnionType(kts) | NirKind::UnionConstructor(_, kts) => {
-                for x in kts.values().flatten() {
-                    x.normalize();
-                }
-            }
-            NirKind::UnionLit(_, v, kts) => {
-                v.normalize();
-                for x in kts.values().flatten() {
-                    x.normalize();
-                }
-            }
-            NirKind::TextLit(tlit) => tlit.normalize(),
-            NirKind::Equivalence(x, y) => {
-                x.normalize();
-                y.normalize();
-            }
-            NirKind::PartialExpr(e) => {
-                e.map_ref(Nir::normalize);
-            }
-        }
-    }
-
-    pub(crate) fn from_builtin(b: Builtin) -> NirKind {
+    pub fn from_builtin(b: Builtin) -> NirKind {
         NirKind::from_builtin_env(b, NzEnv::new())
     }
-    pub(crate) fn from_builtin_env(b: Builtin, env: NzEnv) -> NirKind {
-        NirKind::AppliedBuiltin(BuiltinClosure::new(b, env))
+    pub fn from_builtin_env(b: Builtin, env: NzEnv) -> NirKind {
+        BuiltinClosure::new(b, env)
     }
 }
 
@@ -390,9 +342,6 @@ impl Closure {
         }
     }
 
-    // TODO: somehow normalize the body. Might require to pass an env.
-    pub fn normalize(&self) {}
-
     /// Convert this closure to a Hir expression
     pub fn to_hir(&self, venv: VarEnv) -> Hir {
         self.apply_var(NzVar::new(venv.size()))
@@ -456,13 +405,6 @@ impl TextLit {
     pub fn iter(&self) -> impl Iterator<Item = &InterpolatedTextContents<Nir>> {
         self.0.iter()
     }
-    /// Normalize the contained values. This does not break the invariant because we have already
-    /// ensured that no contained values normalize to a TextLit.
-    pub fn normalize(&self) {
-        for x in self.0.iter() {
-            x.map_ref(Nir::normalize);
-        }
-    }
 }
 
 impl lazy::Eval<NirKind> for Thunk {
diff --git a/dhall/src/semantics/nze/normalize.rs b/dhall/src/semantics/nze/normalize.rs
index 79d55e8..570e106 100644
--- a/dhall/src/semantics/nze/normalize.rs
+++ b/dhall/src/semantics/nze/normalize.rs
@@ -2,14 +2,10 @@ use itertools::Itertools;
 use std::collections::HashMap;
 
 use crate::semantics::NzEnv;
-use crate::semantics::{
-    Binder, BuiltinClosure, Closure, Hir, HirKind, Nir, NirKind, TextLit,
-};
-use crate::syntax::{
-    BinOp, Builtin, ExprKind, InterpolatedTextContents, LitKind,
-};
+use crate::semantics::{Binder, Closure, Hir, HirKind, Nir, NirKind, TextLit};
+use crate::syntax::{BinOp, ExprKind, InterpolatedTextContents, NumKind};
 
-pub(crate) fn apply_any(f: Nir, a: Nir) -> NirKind {
+pub fn apply_any(f: Nir, a: Nir) -> NirKind {
     match f.kind() {
         NirKind::LamClosure { closure, .. } => closure.apply(a).kind().clone(),
         NirKind::AppliedBuiltin(closure) => closure.apply(a),
@@ -20,7 +16,7 @@ pub(crate) fn apply_any(f: Nir, a: Nir) -> NirKind {
     }
 }
 
-pub(crate) fn squash_textlit(
+pub fn squash_textlit(
     elts: impl Iterator<Item = InterpolatedTextContents<Nir>>,
 ) -> Vec<InterpolatedTextContents<Nir>> {
     use std::mem::replace;
@@ -58,7 +54,7 @@ pub(crate) fn squash_textlit(
     ret
 }
 
-pub(crate) fn merge_maps<K, V, F>(
+pub fn merge_maps<K, V, F>(
     map1: &HashMap<K, V>,
     map2: &HashMap<K, V>,
     mut f: F,
@@ -99,40 +95,40 @@ fn apply_binop<'a>(o: BinOp, x: &'a Nir, y: &'a Nir) -> Option<Ret<'a>> {
         NaturalTimes, RecursiveRecordMerge, RecursiveRecordTypeMerge,
         RightBiasedRecordMerge, TextAppend,
     };
-    use LitKind::{Bool, Natural};
-    use NirKind::{EmptyListLit, Lit, NEListLit, RecordLit, RecordType};
+    use NirKind::{EmptyListLit, NEListLit, Num, RecordLit, RecordType};
+    use NumKind::{Bool, Natural};
 
     Some(match (o, x.kind(), y.kind()) {
-        (BoolAnd, Lit(Bool(true)), _) => Ret::NirRef(y),
-        (BoolAnd, _, Lit(Bool(true))) => Ret::NirRef(x),
-        (BoolAnd, Lit(Bool(false)), _) => Ret::NirKind(Lit(Bool(false))),
-        (BoolAnd, _, Lit(Bool(false))) => Ret::NirKind(Lit(Bool(false))),
+        (BoolAnd, Num(Bool(true)), _) => Ret::NirRef(y),
+        (BoolAnd, _, Num(Bool(true))) => Ret::NirRef(x),
+        (BoolAnd, Num(Bool(false)), _) => Ret::NirKind(Num(Bool(false))),
+        (BoolAnd, _, Num(Bool(false))) => Ret::NirKind(Num(Bool(false))),
         (BoolAnd, _, _) if x == y => Ret::NirRef(x),
-        (BoolOr, Lit(Bool(true)), _) => Ret::NirKind(Lit(Bool(true))),
-        (BoolOr, _, Lit(Bool(true))) => Ret::NirKind(Lit(Bool(true))),
-        (BoolOr, Lit(Bool(false)), _) => Ret::NirRef(y),
-        (BoolOr, _, Lit(Bool(false))) => Ret::NirRef(x),
+        (BoolOr, Num(Bool(true)), _) => Ret::NirKind(Num(Bool(true))),
+        (BoolOr, _, Num(Bool(true))) => Ret::NirKind(Num(Bool(true))),
+        (BoolOr, Num(Bool(false)), _) => Ret::NirRef(y),
+        (BoolOr, _, Num(Bool(false))) => Ret::NirRef(x),
         (BoolOr, _, _) if x == y => Ret::NirRef(x),
-        (BoolEQ, Lit(Bool(true)), _) => Ret::NirRef(y),
-        (BoolEQ, _, Lit(Bool(true))) => Ret::NirRef(x),
-        (BoolEQ, Lit(Bool(x)), Lit(Bool(y))) => Ret::NirKind(Lit(Bool(x == y))),
-        (BoolEQ, _, _) if x == y => Ret::NirKind(Lit(Bool(true))),
-        (BoolNE, Lit(Bool(false)), _) => Ret::NirRef(y),
-        (BoolNE, _, Lit(Bool(false))) => Ret::NirRef(x),
-        (BoolNE, Lit(Bool(x)), Lit(Bool(y))) => Ret::NirKind(Lit(Bool(x != y))),
-        (BoolNE, _, _) if x == y => Ret::NirKind(Lit(Bool(false))),
+        (BoolEQ, Num(Bool(true)), _) => Ret::NirRef(y),
+        (BoolEQ, _, Num(Bool(true))) => Ret::NirRef(x),
+        (BoolEQ, Num(Bool(x)), Num(Bool(y))) => Ret::NirKind(Num(Bool(x == y))),
+        (BoolEQ, _, _) if x == y => Ret::NirKind(Num(Bool(true))),
+        (BoolNE, Num(Bool(false)), _) => Ret::NirRef(y),
+        (BoolNE, _, Num(Bool(false))) => Ret::NirRef(x),
+        (BoolNE, Num(Bool(x)), Num(Bool(y))) => Ret::NirKind(Num(Bool(x != y))),
+        (BoolNE, _, _) if x == y => Ret::NirKind(Num(Bool(false))),
 
-        (NaturalPlus, Lit(Natural(0)), _) => Ret::NirRef(y),
-        (NaturalPlus, _, Lit(Natural(0))) => Ret::NirRef(x),
-        (NaturalPlus, Lit(Natural(x)), Lit(Natural(y))) => {
-            Ret::NirKind(Lit(Natural(x + y)))
+        (NaturalPlus, Num(Natural(0)), _) => Ret::NirRef(y),
+        (NaturalPlus, _, Num(Natural(0))) => Ret::NirRef(x),
+        (NaturalPlus, Num(Natural(x)), Num(Natural(y))) => {
+            Ret::NirKind(Num(Natural(x + y)))
         }
-        (NaturalTimes, Lit(Natural(0)), _) => Ret::NirKind(Lit(Natural(0))),
-        (NaturalTimes, _, Lit(Natural(0))) => Ret::NirKind(Lit(Natural(0))),
-        (NaturalTimes, Lit(Natural(1)), _) => Ret::NirRef(y),
-        (NaturalTimes, _, Lit(Natural(1))) => Ret::NirRef(x),
-        (NaturalTimes, Lit(Natural(x)), Lit(Natural(y))) => {
-            Ret::NirKind(Lit(Natural(x * y)))
+        (NaturalTimes, Num(Natural(0)), _) => Ret::NirKind(Num(Natural(0))),
+        (NaturalTimes, _, Num(Natural(0))) => Ret::NirKind(Num(Natural(0))),
+        (NaturalTimes, Num(Natural(1)), _) => Ret::NirRef(y),
+        (NaturalTimes, _, Num(Natural(1))) => Ret::NirRef(x),
+        (NaturalTimes, Num(Natural(x)), Num(Natural(y))) => {
+            Ret::NirKind(Num(Natural(x * y)))
         }
 
         (ListAppend, EmptyListLit(_), _) => Ret::NirRef(y),
@@ -211,13 +207,13 @@ fn apply_binop<'a>(o: BinOp, x: &'a Nir, y: &'a Nir) -> Option<Ret<'a>> {
 }
 
 #[allow(clippy::cognitive_complexity)]
-pub(crate) fn normalize_one_layer(expr: ExprKind<Nir>, env: &NzEnv) -> NirKind {
-    use LitKind::Bool;
+pub fn normalize_one_layer(expr: ExprKind<Nir>, env: &NzEnv) -> NirKind {
     use NirKind::{
-        EmptyListLit, EmptyOptionalLit, Lit, NEListLit, NEOptionalLit,
+        EmptyListLit, EmptyOptionalLit, NEListLit, NEOptionalLit, Num,
         PartialExpr, RecordLit, RecordType, UnionConstructor, UnionLit,
         UnionType,
     };
+    use NumKind::Bool;
 
     let ret = match expr {
         ExprKind::Import(..) | ExprKind::Completion(..) => {
@@ -235,15 +231,11 @@ pub(crate) fn normalize_one_layer(expr: ExprKind<Nir>, env: &NzEnv) -> NirKind {
         ExprKind::Builtin(b) => Ret::Nir(Nir::from_builtin_env(b, env)),
         ExprKind::Assert(_) => Ret::Expr(expr),
         ExprKind::App(v, a) => Ret::Nir(v.app(a)),
-        ExprKind::Lit(l) => Ret::NirKind(Lit(l)),
+        ExprKind::Num(l) => Ret::NirKind(Num(l)),
         ExprKind::SomeLit(e) => Ret::NirKind(NEOptionalLit(e)),
         ExprKind::EmptyListLit(t) => {
             let arg = match t.kind() {
-                NirKind::AppliedBuiltin(BuiltinClosure {
-                    b: Builtin::List,
-                    args,
-                    ..
-                }) if args.len() == 1 => args[0].clone(),
+                NirKind::ListType(t) => t.clone(),
                 _ => panic!("internal type error"),
             };
             Ret::NirKind(NirKind::EmptyListLit(arg))
@@ -271,12 +263,12 @@ pub(crate) fn normalize_one_layer(expr: ExprKind<Nir>, env: &NzEnv) -> NirKind {
         }
         ExprKind::BoolIf(ref b, ref e1, ref e2) => {
             match b.kind() {
-                Lit(Bool(true)) => Ret::NirRef(e1),
-                Lit(Bool(false)) => Ret::NirRef(e2),
+                Num(Bool(true)) => Ret::NirRef(e1),
+                Num(Bool(false)) => Ret::NirRef(e2),
                 _ => {
                     match (e1.kind(), e2.kind()) {
                         // Simplify `if b then True else False`
-                        (Lit(Bool(true)), Lit(Bool(false))) => Ret::NirRef(b),
+                        (Num(Bool(true)), Num(Bool(false))) => Ret::NirRef(b),
                         _ if e1 == e2 => Ret::NirRef(e1),
                         _ => Ret::Expr(expr),
                     }
@@ -442,12 +434,8 @@ pub(crate) fn normalize_one_layer(expr: ExprKind<Nir>, env: &NzEnv) -> NirKind {
         ExprKind::ToMap(ref v, ref annot) => match v.kind() {
             RecordLit(kvs) if kvs.is_empty() => {
                 match annot.as_ref().map(|v| v.kind()) {
-                    Some(NirKind::AppliedBuiltin(BuiltinClosure {
-                        b: Builtin::List,
-                        args,
-                        ..
-                    })) if args.len() == 1 => {
-                        Ret::NirKind(EmptyListLit(args[0].clone()))
+                    Some(NirKind::ListType(t)) => {
+                        Ret::NirKind(EmptyListLit(t.clone()))
                     }
                     _ => Ret::Expr(expr),
                 }
@@ -476,7 +464,7 @@ pub(crate) fn normalize_one_layer(expr: ExprKind<Nir>, env: &NzEnv) -> NirKind {
 }
 
 /// Normalize Hir into WHNF
-pub(crate) fn normalize_hir_whnf(env: &NzEnv, hir: &Hir) -> NirKind {
+pub fn normalize_hir_whnf(env: &NzEnv, hir: &Hir) -> NirKind {
     match hir.kind() {
         HirKind::Var(var) => env.lookup_val(*var),
         HirKind::Import(hir, _) => normalize_hir_whnf(env, hir),
diff --git a/dhall/src/semantics/nze/var.rs b/dhall/src/semantics/nze/var.rs
index 413c759..302dbb7 100644
--- a/dhall/src/semantics/nze/var.rs
+++ b/dhall/src/semantics/nze/var.rs
@@ -8,10 +8,10 @@ pub struct Binder {
 }
 
 impl Binder {
-    pub(crate) fn new(name: Label) -> Self {
+    pub fn new(name: Label) -> Self {
         Binder { name }
     }
-    pub(crate) fn to_label(&self) -> Label {
+    pub fn to_label(&self) -> Label {
         self.clone().into()
     }
 }
diff --git a/dhall/src/semantics/parse.rs b/dhall/src/semantics/parse.rs
index 45860d0..2326471 100644
--- a/dhall/src/semantics/parse.rs
+++ b/dhall/src/semantics/parse.rs
@@ -9,33 +9,33 @@ use crate::syntax::binary;
 use crate::syntax::parse_expr;
 use crate::Parsed;
 
-pub(crate) fn parse_file(f: &Path) -> Result<Parsed, Error> {
+pub fn parse_file(f: &Path) -> Result<Parsed, Error> {
     let text = std::fs::read_to_string(f)?;
     let expr = parse_expr(&text)?;
     let root = ImportLocation::Local(f.to_owned());
     Ok(Parsed(expr, root))
 }
 
-pub(crate) fn parse_remote(url: Url) -> Result<Parsed, Error> {
+pub fn parse_remote(url: Url) -> Result<Parsed, Error> {
     let body = reqwest::blocking::get(url.clone()).unwrap().text().unwrap();
     let expr = parse_expr(&body)?;
     let root = ImportLocation::Remote(url);
     Ok(Parsed(expr, root))
 }
 
-pub(crate) fn parse_str(s: &str) -> Result<Parsed, Error> {
+pub fn parse_str(s: &str) -> Result<Parsed, Error> {
     let expr = parse_expr(s)?;
     let root = ImportLocation::Missing;
     Ok(Parsed(expr, root))
 }
 
-pub(crate) fn parse_binary(data: &[u8]) -> Result<Parsed, Error> {
+pub fn parse_binary(data: &[u8]) -> Result<Parsed, Error> {
     let expr = binary::decode(data)?;
     let root = ImportLocation::Missing;
     Ok(Parsed(expr, root))
 }
 
-pub(crate) fn parse_binary_file(f: &Path) -> Result<Parsed, Error> {
+pub fn parse_binary_file(f: &Path) -> Result<Parsed, Error> {
     let mut buffer = Vec::new();
     File::open(f)?.read_to_end(&mut buffer)?;
     let expr = binary::decode(&buffer)?;
diff --git a/dhall/src/semantics/resolve/env.rs b/dhall/src/semantics/resolve/env.rs
index fe8c178..d7ff0ae 100644
--- a/dhall/src/semantics/resolve/env.rs
+++ b/dhall/src/semantics/resolve/env.rs
@@ -5,24 +5,24 @@ use crate::semantics::{AlphaVar, ImportLocation, TypedHir, VarEnv};
 use crate::syntax::{Label, V};
 
 /// Environment for resolving names.
-#[derive(Debug, Clone)]
-pub(crate) struct NameEnv {
+#[derive(Debug, Clone, Default)]
+pub struct NameEnv {
     names: Vec<Label>,
 }
 
-pub(crate) type ImportCache = HashMap<ImportLocation, TypedHir>;
-pub(crate) type ImportStack = Vec<ImportLocation>;
+pub type ImportCache = HashMap<ImportLocation, TypedHir>;
+pub type ImportStack = Vec<ImportLocation>;
 
 /// Environment for resolving imports
-#[derive(Debug, Clone)]
-pub(crate) struct ImportEnv {
+#[derive(Debug, Clone, Default)]
+pub struct ImportEnv {
     cache: ImportCache,
     stack: ImportStack,
 }
 
 impl NameEnv {
     pub fn new() -> Self {
-        NameEnv { names: Vec::new() }
+        NameEnv::default()
     }
     pub fn as_varenv(&self) -> VarEnv {
         VarEnv::from_size(self.names.len())
@@ -66,10 +66,7 @@ impl NameEnv {
 
 impl ImportEnv {
     pub fn new() -> Self {
-        ImportEnv {
-            cache: HashMap::new(),
-            stack: Vec::new(),
-        }
+        ImportEnv::default()
     }
 
     pub fn handle_import(
diff --git a/dhall/src/semantics/resolve/hir.rs b/dhall/src/semantics/resolve/hir.rs
index fa2989f..9256425 100644
--- a/dhall/src/semantics/resolve/hir.rs
+++ b/dhall/src/semantics/resolve/hir.rs
@@ -1,7 +1,7 @@
 use crate::error::TypeError;
 use crate::semantics::{type_with, NameEnv, Nir, NzEnv, Tir, TyEnv, Type};
 use crate::syntax::{Expr, ExprKind, Span, V};
-use crate::{NormalizedExpr, ToExprOptions};
+use crate::ToExprOptions;
 
 /// Stores an alpha-normalized variable.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
@@ -10,7 +10,7 @@ pub struct AlphaVar {
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
-pub(crate) enum HirKind {
+pub enum HirKind {
     /// A resolved variable (i.e. a DeBruijn index)
     Var(AlphaVar),
     /// Result of resolving an import.
@@ -21,16 +21,16 @@ pub(crate) enum HirKind {
 
 // An expression with resolved variables and imports.
 #[derive(Debug, Clone)]
-pub(crate) struct Hir {
+pub struct Hir {
     kind: Box<HirKind>,
     span: Span,
 }
 
 impl AlphaVar {
-    pub(crate) fn new(idx: usize) -> Self {
+    pub fn new(idx: usize) -> Self {
         AlphaVar { idx }
     }
-    pub(crate) fn idx(self) -> usize {
+    pub fn idx(self) -> usize {
         self.idx
     }
 }
@@ -51,15 +51,15 @@ impl Hir {
     }
 
     /// Converts a closed Hir expr back to the corresponding AST expression.
-    pub fn to_expr(&self, opts: ToExprOptions) -> NormalizedExpr {
+    pub fn to_expr(&self, opts: ToExprOptions) -> Expr {
         hir_to_expr(self, opts, &mut NameEnv::new())
     }
     /// Converts a closed Hir expr back to the corresponding AST expression.
-    pub fn to_expr_noopts(&self) -> NormalizedExpr {
+    pub fn to_expr_noopts(&self) -> Expr {
         let opts = ToExprOptions { alpha: false };
         self.to_expr(opts)
     }
-    pub fn to_expr_tyenv(&self, env: &TyEnv) -> NormalizedExpr {
+    pub fn to_expr_tyenv(&self, env: &TyEnv) -> Expr {
         let opts = ToExprOptions { alpha: false };
         let mut env = env.as_nameenv().clone();
         hir_to_expr(self, opts, &mut env)
@@ -85,19 +85,9 @@ impl Hir {
     pub fn eval_closed_expr(&self) -> Nir {
         self.eval(NzEnv::new())
     }
-    /// Eval a closed Hir fully and recursively;
-    pub fn rec_eval_closed_expr(&self) -> Nir {
-        let val = self.eval_closed_expr();
-        val.normalize();
-        val
-    }
 }
 
-fn hir_to_expr(
-    hir: &Hir,
-    opts: ToExprOptions,
-    env: &mut NameEnv,
-) -> NormalizedExpr {
+fn hir_to_expr(hir: &Hir, opts: ToExprOptions, env: &mut NameEnv) -> Expr {
     let kind = match hir.kind() {
         HirKind::Var(v) if opts.alpha => ExprKind::Var(V("_".into(), v.idx())),
         HirKind::Var(v) => ExprKind::Var(env.label_var(*v)),
diff --git a/dhall/src/semantics/resolve/mod.rs b/dhall/src/semantics/resolve/mod.rs
index 517907b..33b477e 100644
--- a/dhall/src/semantics/resolve/mod.rs
+++ b/dhall/src/semantics/resolve/mod.rs
@@ -1,6 +1,6 @@
 pub mod env;
 pub mod hir;
 pub mod resolve;
-pub(crate) use env::*;
-pub(crate) use hir::*;
-pub(crate) use resolve::*;
+pub use env::*;
+pub use hir::*;
+pub use resolve::*;
diff --git a/dhall/src/semantics/resolve/resolve.rs b/dhall/src/semantics/resolve/resolve.rs
index f3fda4b..7745e0b 100644
--- a/dhall/src/semantics/resolve/resolve.rs
+++ b/dhall/src/semantics/resolve/resolve.rs
@@ -13,17 +13,17 @@ use crate::syntax::{
     BinOp, Builtin, Expr, ExprKind, FilePath, FilePrefix, ImportMode,
     ImportTarget, Span, UnspannedExpr, URL,
 };
-use crate::{Parsed, ParsedExpr, Resolved};
+use crate::{Parsed, Resolved};
 
 // TODO: evaluate import headers
-pub(crate) type Import = syntax::Import<()>;
+pub type Import = syntax::Import<()>;
 
 /// Owned Hir with a type. Different from Tir because the Hir is owned.
-pub(crate) type TypedHir = (Hir, Type);
+pub type TypedHir = (Hir, Type);
 
 /// The location of some data, usually some dhall code.
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
-pub(crate) enum ImportLocation {
+pub enum ImportLocation {
     /// Local file
     Local(PathBuf),
     /// Remote file
@@ -227,7 +227,7 @@ fn resolve_one_import(
         }
         ImportMode::Location => {
             let expr = location.into_location();
-            let hir = skip_resolve(&expr)?;
+            let hir = skip_resolve_expr(&expr)?;
             let ty = hir.typecheck_noenv()?.ty().clone();
             Ok((hir, ty))
         }
@@ -329,16 +329,22 @@ fn resolve_with_env(
     Ok(Resolved(resolved))
 }
 
-pub(crate) fn resolve(parsed: Parsed) -> Result<Resolved, Error> {
+pub fn resolve(parsed: Parsed) -> Result<Resolved, Error> {
     resolve_with_env(&mut ImportEnv::new(), parsed)
 }
 
-pub(crate) fn skip_resolve(expr: &ParsedExpr) -> Result<Hir, Error> {
+pub fn skip_resolve_expr(expr: &Expr) -> Result<Hir, Error> {
     traverse_resolve_expr(&mut NameEnv::new(), expr, &mut |import| {
         Err(ImportError::UnexpectedImport(import).into())
     })
 }
 
+pub fn skip_resolve(parsed: Parsed) -> Result<Resolved, Error> {
+    let Parsed(expr, _) = parsed;
+    let resolved = skip_resolve_expr(&expr)?;
+    Ok(Resolved(resolved))
+}
+
 pub trait Canonicalize {
     fn canonicalize(&self) -> Self;
 }
diff --git a/dhall/src/semantics/tck/env.rs b/dhall/src/semantics/tck/env.rs
index 6dd5076..1fa66f0 100644
--- a/dhall/src/semantics/tck/env.rs
+++ b/dhall/src/semantics/tck/env.rs
@@ -2,21 +2,21 @@ use crate::semantics::{AlphaVar, NameEnv, Nir, NzEnv, NzVar, Type, ValEnv};
 use crate::syntax::Label;
 
 /// Environment for indexing variables.
-#[derive(Debug, Clone, Copy)]
-pub(crate) struct VarEnv {
+#[derive(Debug, Clone, Copy, Default)]
+pub struct VarEnv {
     size: usize,
 }
 
 /// Environment for typing expressions.
 #[derive(Debug, Clone)]
-pub(crate) struct TyEnv {
+pub struct TyEnv {
     names: NameEnv,
     items: ValEnv<Type>,
 }
 
 impl VarEnv {
     pub fn new() -> Self {
-        VarEnv { size: 0 }
+        VarEnv::default()
     }
     pub fn from_size(size: usize) -> Self {
         VarEnv { size }
diff --git a/dhall/src/semantics/tck/mod.rs b/dhall/src/semantics/tck/mod.rs
index 93c8f48..6dddfc5 100644
--- a/dhall/src/semantics/tck/mod.rs
+++ b/dhall/src/semantics/tck/mod.rs
@@ -1,6 +1,6 @@
 pub mod env;
 pub mod tir;
 pub mod typecheck;
-pub(crate) use env::*;
-pub(crate) use tir::*;
-pub(crate) use typecheck::*;
+pub use env::*;
+pub use tir::*;
+pub use typecheck::*;
diff --git a/dhall/src/semantics/tck/tir.rs b/dhall/src/semantics/tck/tir.rs
index aeb7bf9..89a8027 100644
--- a/dhall/src/semantics/tck/tir.rs
+++ b/dhall/src/semantics/tck/tir.rs
@@ -1,15 +1,14 @@
 use crate::error::{ErrorBuilder, TypeError};
 use crate::semantics::{mkerr, Hir, Nir, NirKind, NzEnv, TyEnv, VarEnv};
-use crate::syntax::{Builtin, Const, Span};
-use crate::NormalizedExpr;
+use crate::syntax::{Builtin, Const, Expr, Span};
 
 /// The type of a type. 0 is `Type`, 1 is `Kind`, etc...
 #[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Default)]
-pub(crate) struct Universe(u8);
+pub struct Universe(u8);
 
 /// An expression representing a type
 #[derive(Debug, Clone, PartialEq, Eq)]
-pub(crate) struct Type {
+pub struct Type {
     val: Nir,
     univ: Universe,
 }
@@ -17,7 +16,7 @@ pub(crate) struct Type {
 /// A hir expression plus its inferred type.
 /// Stands for "Typed intermediate representation"
 #[derive(Debug, Clone)]
-pub(crate) struct Tir<'hir> {
+pub struct Tir<'hir> {
     hir: &'hir Hir,
     ty: Type,
 }
@@ -101,7 +100,7 @@ impl Type {
     pub fn to_hir(&self, venv: VarEnv) -> Hir {
         self.val.to_hir(venv)
     }
-    pub fn to_expr_tyenv(&self, tyenv: &TyEnv) -> NormalizedExpr {
+    pub fn to_expr_tyenv(&self, tyenv: &TyEnv) -> Expr {
         self.val.to_hir(tyenv.as_varenv()).to_expr_tyenv(tyenv)
     }
 }
@@ -124,7 +123,7 @@ impl<'hir> Tir<'hir> {
     pub fn as_hir(&self) -> &Hir {
         &self.hir
     }
-    pub fn to_expr_tyenv(&self, env: &TyEnv) -> NormalizedExpr {
+    pub fn to_expr_tyenv(&self, env: &TyEnv) -> Expr {
         self.as_hir().to_expr_tyenv(env)
     }
 
diff --git a/dhall/src/semantics/tck/typecheck.rs b/dhall/src/semantics/tck/typecheck.rs
index 173b76d..c3334b5 100644
--- a/dhall/src/semantics/tck/typecheck.rs
+++ b/dhall/src/semantics/tck/typecheck.rs
@@ -5,11 +5,11 @@ use std::collections::HashMap;
 use crate::error::{ErrorBuilder, TypeError, TypeMessage};
 use crate::semantics::merge_maps;
 use crate::semantics::{
-    type_of_builtin, Binder, BuiltinClosure, Closure, Hir, HirKind, Nir,
-    NirKind, Tir, TyEnv, Type,
+    type_of_builtin, Binder, Closure, Hir, HirKind, Nir, NirKind, Tir, TyEnv,
+    Type,
 };
 use crate::syntax::{
-    BinOp, Builtin, Const, ExprKind, InterpolatedTextContents, LitKind, Span,
+    BinOp, Builtin, Const, ExprKind, InterpolatedTextContents, NumKind, Span,
 };
 
 fn check_rectymerge(
@@ -53,14 +53,11 @@ fn function_check(a: Const, b: Const) -> Const {
     }
 }
 
-pub(crate) fn mkerr<T, S: ToString>(msg: S) -> Result<T, TypeError> {
+pub fn mkerr<T, S: ToString>(msg: S) -> Result<T, TypeError> {
     Err(TypeError::new(TypeMessage::Custom(msg.to_string())))
 }
 
-pub(crate) fn mk_span_err<T, S: ToString>(
-    span: Span,
-    msg: S,
-) -> Result<T, TypeError> {
+pub fn mk_span_err<T, S: ToString>(span: Span, msg: S) -> Result<T, TypeError> {
     mkerr(
         ErrorBuilder::new(msg.to_string())
             .span_err(span, msg.to_string())
@@ -96,14 +93,14 @@ fn type_one_layer(
             let t_hir = type_of_builtin(*b);
             typecheck(&t_hir)?.eval_to_type(env)?
         }
-        ExprKind::Lit(LitKind::Bool(_)) => Type::from_builtin(Builtin::Bool),
-        ExprKind::Lit(LitKind::Natural(_)) => {
+        ExprKind::Num(NumKind::Bool(_)) => Type::from_builtin(Builtin::Bool),
+        ExprKind::Num(NumKind::Natural(_)) => {
             Type::from_builtin(Builtin::Natural)
         }
-        ExprKind::Lit(LitKind::Integer(_)) => {
+        ExprKind::Num(NumKind::Integer(_)) => {
             Type::from_builtin(Builtin::Integer)
         }
-        ExprKind::Lit(LitKind::Double(_)) => {
+        ExprKind::Num(NumKind::Double(_)) => {
             Type::from_builtin(Builtin::Double)
         }
         ExprKind::TextLit(interpolated) => {
@@ -121,11 +118,7 @@ fn type_one_layer(
         ExprKind::EmptyListLit(t) => {
             let t = t.eval_to_type(env)?;
             match t.kind() {
-                NirKind::AppliedBuiltin(BuiltinClosure {
-                    b: Builtin::List,
-                    args,
-                    ..
-                }) if args.len() == 1 => {}
+                NirKind::ListType(..) => {}
                 _ => return span_err("InvalidListType"),
             };
             t
@@ -376,10 +369,7 @@ fn type_one_layer(
         }
         ExprKind::BinOp(BinOp::ListAppend, l, r) => {
             match l.ty().kind() {
-                NirKind::AppliedBuiltin(BuiltinClosure {
-                    b: Builtin::List,
-                    ..
-                }) => {}
+                NirKind::ListType(..) => {}
                 _ => return span_err("BinOpTypeMismatch"),
             }
 
@@ -435,12 +425,7 @@ fn type_one_layer(
             let union_type = union.ty();
             let variants = match union_type.kind() {
                 NirKind::UnionType(kts) => Cow::Borrowed(kts),
-                NirKind::AppliedBuiltin(BuiltinClosure {
-                    b: Builtin::Optional,
-                    args,
-                    ..
-                }) if args.len() == 1 => {
-                    let ty = &args[0];
+                NirKind::OptionalType(ty) => {
                     let mut kts = HashMap::new();
                     kts.insert("None".into(), None);
                     kts.insert("Some".into(), Some(ty.clone()));
@@ -595,11 +580,7 @@ fn type_one_layer(
                 let err_msg = "The type of `toMap x` must be of the form \
                                `List { mapKey : Text, mapValue : T }`";
                 let arg = match annot_val.kind() {
-                    NirKind::AppliedBuiltin(BuiltinClosure {
-                        b: Builtin::List,
-                        args,
-                        ..
-                    }) if args.len() == 1 => &args[0],
+                    NirKind::ListType(t) => t,
                     _ => return span_err(err_msg),
                 };
                 let kts = match arg.kind() {
@@ -704,7 +685,7 @@ fn type_one_layer(
 
 /// `type_with` typechecks an expression in the provided environment. Optionally pass an annotation
 /// to compare with.
-pub(crate) fn type_with<'hir>(
+pub fn type_with<'hir>(
     env: &TyEnv,
     hir: &'hir Hir,
     annot: Option<Type>,
@@ -801,15 +782,15 @@ pub(crate) fn type_with<'hir>(
 
 /// Typecheck an expression and return the expression annotated with types if type-checking
 /// succeeded, or an error if type-checking failed.
-pub(crate) fn typecheck<'hir>(hir: &'hir Hir) -> Result<Tir<'hir>, TypeError> {
+pub fn typecheck<'hir>(hir: &'hir Hir) -> Result<Tir<'hir>, TypeError> {
     type_with(&TyEnv::new(), hir, None)
 }
 
 /// Like `typecheck`, but additionally checks that the expression's type matches the provided type.
-pub(crate) fn typecheck_with<'hir>(
+pub 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/dhall/src/syntax/ast/expr.rs b/dhall/src/syntax/ast/expr.rs
index b53e6cb..6ba6649 100644
--- a/dhall/src/syntax/ast/expr.rs
+++ b/dhall/src/syntax/ast/expr.rs
@@ -22,7 +22,7 @@ pub enum Const {
 }
 
 impl Const {
-    pub(crate) fn to_universe(self) -> Universe {
+    pub fn to_universe(self) -> Universe {
         Universe::from_const(self)
     }
 }
@@ -112,9 +112,9 @@ pub struct Expr {
 
 pub type UnspannedExpr = ExprKind<Expr>;
 
-/// Simple literals
+/// Numeric literals
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
-pub enum LitKind {
+pub enum NumKind {
     ///  `True`
     Bool(bool),
     ///  `1`
@@ -132,7 +132,7 @@ pub enum LitKind {
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum ExprKind<SubExpr> {
     Const(Const),
-    Lit(LitKind),
+    Num(NumKind),
     ///  `x`
     ///  `x@n`
     Var(V),
@@ -205,7 +205,7 @@ impl<SE> ExprKind<SE> {
         })
     }
 
-    pub(crate) fn traverse_ref<'a, SE2, Err>(
+    pub fn traverse_ref<'a, SE2, Err>(
         &'a self,
         mut visit_subexpr: impl FnMut(&'a SE) -> Result<SE2, Err>,
     ) -> Result<ExprKind<SE2>, Err> {
@@ -239,17 +239,17 @@ impl<SE> ExprKind<SE> {
 }
 
 impl Expr {
-    pub(crate) fn as_ref(&self) -> &UnspannedExpr {
+    pub fn as_ref(&self) -> &UnspannedExpr {
         &self.kind
     }
     pub fn kind(&self) -> &UnspannedExpr {
         &self.kind
     }
-    pub(crate) fn span(&self) -> Span {
+    pub fn span(&self) -> Span {
         self.span.clone()
     }
 
-    pub(crate) fn new(kind: UnspannedExpr, span: Span) -> Self {
+    pub fn new(kind: UnspannedExpr, span: Span) -> Self {
         Expr {
             kind: Box::new(kind),
             span,
diff --git a/dhall/src/syntax/ast/mod.rs b/dhall/src/syntax/ast/mod.rs
index 5e20c5d..1950154 100644
--- a/dhall/src/syntax/ast/mod.rs
+++ b/dhall/src/syntax/ast/mod.rs
@@ -5,7 +5,7 @@ pub use import::*;
 mod label;
 pub use label::*;
 mod span;
-pub(crate) use span::*;
+pub use span::*;
 mod text;
 pub use text::*;
 pub mod map;
diff --git a/dhall/src/syntax/ast/span.rs b/dhall/src/syntax/ast/span.rs
index 2e09863..e250602 100644
--- a/dhall/src/syntax/ast/span.rs
+++ b/dhall/src/syntax/ast/span.rs
@@ -2,7 +2,7 @@ use std::rc::Rc;
 
 /// A location in the source text
 #[derive(Debug, Clone)]
-pub(crate) struct ParsedSpan {
+pub struct ParsedSpan {
     input: Rc<str>,
     /// # Safety
     ///
@@ -15,7 +15,7 @@ pub(crate) struct ParsedSpan {
 }
 
 #[derive(Debug, Clone)]
-pub(crate) enum Span {
+pub enum Span {
     /// A location in the source text
     Parsed(ParsedSpan),
     /// Desugarings
@@ -30,12 +30,12 @@ pub(crate) enum Span {
 }
 
 impl ParsedSpan {
-    pub(crate) fn to_input(&self) -> String {
+    pub fn to_input(&self) -> String {
         self.input.to_string()
     }
     /// Convert to a char range for consumption by annotate_snippets.
     /// This compensates for  https://github.com/rust-lang/annotate-snippets-rs/issues/24
-    pub(crate) fn as_char_range(&self) -> (usize, usize) {
+    pub fn as_char_range(&self) -> (usize, usize) {
         (
             char_idx_from_byte_idx(&self.input, self.start),
             char_idx_from_byte_idx(&self.input, self.end),
@@ -44,7 +44,7 @@ impl ParsedSpan {
 }
 
 impl Span {
-    pub(crate) fn make(input: Rc<str>, sp: pest::Span) -> Self {
+    pub fn make(input: Rc<str>, sp: pest::Span) -> Self {
         Span::Parsed(ParsedSpan {
             input,
             start: sp.start(),
@@ -55,7 +55,7 @@ impl Span {
     /// Takes the union of the two spans, i.e. the range of input covered by the two spans plus any
     /// input between them. Assumes that the spans come from the same input. Fails if one of the
     /// spans does not point to an input location.
-    pub(crate) fn union(&self, other: &Span) -> Self {
+    pub fn union(&self, other: &Span) -> Self {
         use std::cmp::{max, min};
         use Span::*;
         match (self, other) {
diff --git a/dhall/src/syntax/ast/visitor.rs b/dhall/src/syntax/ast/visitor.rs
index c361bc1..0a0c5ef 100644
--- a/dhall/src/syntax/ast/visitor.rs
+++ b/dhall/src/syntax/ast/visitor.rs
@@ -51,7 +51,7 @@ where
         .collect()
 }
 
-pub(crate) fn visit_ref<'a, F, SE1, SE2, Err>(
+pub fn visit_ref<'a, F, SE1, SE2, Err>(
     input: &'a ExprKind<SE1>,
     mut f: F,
 ) -> Result<ExprKind<SE2>, Err>
@@ -91,7 +91,7 @@ where
         Annot(x, t) => Annot(expr!(x)?, expr!(t)?),
         Const(k) => Const(*k),
         Builtin(v) => Builtin(*v),
-        Lit(l) => Lit(l.clone()),
+        Num(n) => Num(n.clone()),
         TextLit(t) => TextLit(t.traverse_ref(|e| expr!(e))?),
         BinOp(o, x, y) => BinOp(*o, expr!(x)?, expr!(y)?),
         BoolIf(b, t, f) => BoolIf(expr!(b)?, expr!(t)?, expr!(f)?),
diff --git a/dhall/src/syntax/binary/decode.rs b/dhall/src/syntax/binary/decode.rs
index 2ecd7e0..3c93419 100644
--- a/dhall/src/syntax/binary/decode.rs
+++ b/dhall/src/syntax/binary/decode.rs
@@ -6,12 +6,12 @@ use crate::error::DecodeError;
 use crate::syntax;
 use crate::syntax::{
     Expr, ExprKind, FilePath, FilePrefix, Hash, ImportMode, ImportTarget,
-    Integer, InterpolatedText, Label, LitKind, Natural, Scheme, Span,
+    Integer, InterpolatedText, Label, Natural, NumKind, Scheme, Span,
     UnspannedExpr, URL, V,
 };
-use crate::DecodedExpr;
+type DecodedExpr = Expr;
 
-pub(crate) fn decode(data: &[u8]) -> Result<DecodedExpr, DecodeError> {
+pub fn decode(data: &[u8]) -> Result<DecodedExpr, DecodeError> {
     match serde_cbor::de::from_slice(data) {
         Ok(v) => cbor_value_to_dhall(&v),
         Err(e) => Err(DecodeError::CBORError(e)),
@@ -31,8 +31,8 @@ fn cbor_value_to_dhall(data: &cbor::Value) -> Result<DecodedExpr, DecodeError> {
         String(s) => match Builtin::parse(s) {
             Some(b) => ExprKind::Builtin(b),
             None => match s.as_str() {
-                "True" => Lit(LitKind::Bool(true)),
-                "False" => Lit(LitKind::Bool(false)),
+                "True" => Num(NumKind::Bool(true)),
+                "False" => Num(NumKind::Bool(false)),
                 "Type" => Const(Const::Type),
                 "Kind" => Const(Const::Kind),
                 "Sort" => Const(Const::Sort),
@@ -44,8 +44,8 @@ fn cbor_value_to_dhall(data: &cbor::Value) -> Result<DecodedExpr, DecodeError> {
             },
         },
         U64(n) => Var(V(Label::from("_"), *n as usize)),
-        F64(x) => Lit(LitKind::Double((*x).into())),
-        Bool(b) => Lit(LitKind::Bool(*b)),
+        F64(x) => Num(NumKind::Double((*x).into())),
+        Bool(b) => Num(NumKind::Bool(*b)),
         Array(vec) => match vec.as_slice() {
             [String(l), U64(n)] => {
                 if l.as_str() == "_" {
@@ -224,9 +224,9 @@ fn cbor_value_to_dhall(data: &cbor::Value) -> Result<DecodedExpr, DecodeError> {
                 let z = cbor_value_to_dhall(&z)?;
                 BoolIf(x, y, z)
             }
-            [U64(15), U64(x)] => Lit(LitKind::Natural(*x as Natural)),
-            [U64(16), U64(x)] => Lit(LitKind::Integer(*x as Integer)),
-            [U64(16), I64(x)] => Lit(LitKind::Integer(*x as Integer)),
+            [U64(15), U64(x)] => Num(NumKind::Natural(*x as Natural)),
+            [U64(16), U64(x)] => Num(NumKind::Integer(*x as Integer)),
+            [U64(16), I64(x)] => Num(NumKind::Integer(*x as Integer)),
             [U64(18), String(first), rest @ ..] => {
                 TextLit(InterpolatedText::from((
                     first.clone(),
diff --git a/dhall/src/syntax/binary/encode.rs b/dhall/src/syntax/binary/encode.rs
index 9e6948e..8d22a9b 100644
--- a/dhall/src/syntax/binary/encode.rs
+++ b/dhall/src/syntax/binary/encode.rs
@@ -10,7 +10,7 @@ use crate::syntax::{
     Scheme, V,
 };
 
-pub(crate) fn encode(expr: &Expr) -> Result<Vec<u8>, EncodeError> {
+pub fn encode(expr: &Expr) -> Result<Vec<u8>, EncodeError> {
     serde_cbor::ser::to_vec(&Serialize::Expr(expr))
         .map_err(EncodeError::CBORError)
 }
@@ -48,7 +48,7 @@ where
     use std::iter::once;
     use syntax::Builtin;
     use syntax::ExprKind::*;
-    use syntax::LitKind::*;
+    use syntax::NumKind::*;
 
     use self::Serialize::{RecordDupMap, RecordMap, UnionMap};
     fn expr(x: &Expr) -> self::Serialize<'_> {
@@ -63,10 +63,10 @@ where
     match e.as_ref() {
         Const(c) => ser.serialize_str(&c.to_string()),
         Builtin(b) => ser.serialize_str(&b.to_string()),
-        Lit(Bool(b)) => ser.serialize_bool(*b),
-        Lit(Natural(n)) => ser_seq!(ser; tag(15), U64(*n as u64)),
-        Lit(Integer(n)) => ser_seq!(ser; tag(16), I64(*n as i64)),
-        Lit(Double(n)) => {
+        Num(Bool(b)) => ser.serialize_bool(*b),
+        Num(Natural(n)) => ser_seq!(ser; tag(15), U64(*n as u64)),
+        Num(Integer(n)) => ser_seq!(ser; tag(16), I64(*n as i64)),
+        Num(Double(n)) => {
             let n: f64 = (*n).into();
             ser.serialize_f64(n)
         }
diff --git a/dhall/src/syntax/binary/mod.rs b/dhall/src/syntax/binary/mod.rs
index 7ed1f6e..98e0520 100644
--- a/dhall/src/syntax/binary/mod.rs
+++ b/dhall/src/syntax/binary/mod.rs
@@ -1,4 +1,4 @@
 mod decode;
 mod encode;
-pub(crate) use decode::decode;
-pub(crate) use encode::encode;
+pub use decode::decode;
+pub use encode::encode;
diff --git a/dhall/src/syntax/text/parser.rs b/dhall/src/syntax/text/parser.rs
index 03211c7..6f5949f 100644
--- a/dhall/src/syntax/text/parser.rs
+++ b/dhall/src/syntax/text/parser.rs
@@ -9,7 +9,7 @@ use pest_consume::{match_nodes, Parser};
 
 use crate::syntax::map::{DupTreeMap, DupTreeSet};
 use crate::syntax::ExprKind::*;
-use crate::syntax::LitKind::*;
+use crate::syntax::NumKind::*;
 use crate::syntax::{
     Double, Expr, FilePath, FilePrefix, Hash, ImportMode, ImportTarget,
     Integer, InterpolatedText, InterpolatedTextContents, Label, NaiveDouble,
@@ -135,7 +135,7 @@ fn insert_recordlit_entry(map: &mut BTreeMap<Label, Expr>, l: Label, e: Expr) {
             entry.insert(e);
         }
         Entry::Occupied(mut entry) => {
-            let dummy = Expr::new(Lit(Bool(false)), Span::Artificial);
+            let dummy = Expr::new(Num(Bool(false)), Span::Artificial);
             let other = entry.insert(dummy);
             entry.insert(Expr::new(
                 BinOp(RecursiveRecordMerge, other, e),
@@ -390,8 +390,8 @@ impl DhallParser {
         let e = match crate::syntax::Builtin::parse(s) {
             Some(b) => Builtin(b),
             None => match s {
-                "True" => Lit(Bool(true)),
-                "False" => Lit(Bool(false)),
+                "True" => Num(Bool(true)),
+                "False" => Num(Bool(false)),
                 "Type" => Const(crate::syntax::Const::Type),
                 "Kind" => Const(crate::syntax::Const::Kind),
                 "Sort" => Const(crate::syntax::Const::Sort),
@@ -924,9 +924,9 @@ impl DhallParser {
     #[alias(expression, shortcut = true)]
     fn primitive_expression(input: ParseInput) -> ParseResult<Expr> {
         Ok(match_nodes!(input.children();
-            [double_literal(n)] => spanned(input, Lit(Double(n))),
-            [natural_literal(n)] => spanned(input, Lit(Natural(n))),
-            [integer_literal(n)] => spanned(input, Lit(Integer(n))),
+            [double_literal(n)] => spanned(input, Num(Double(n))),
+            [natural_literal(n)] => spanned(input, Num(Natural(n))),
+            [integer_literal(n)] => spanned(input, Num(Integer(n))),
             [double_quote_literal(s)] => spanned(input, TextLit(s)),
             [single_quote_literal(s)] => spanned(input, TextLit(s)),
             [record_type_or_literal(e)] => spanned(input, e),
diff --git a/dhall/src/syntax/text/printer.rs b/dhall/src/syntax/text/printer.rs
index 2b7bc2e..378f408 100644
--- a/dhall/src/syntax/text/printer.rs
+++ b/dhall/src/syntax/text/printer.rs
@@ -201,7 +201,7 @@ impl<SE: Display + Clone> Display for ExprKind<SE> {
             Var(a) => a.fmt(f)?,
             Const(k) => k.fmt(f)?,
             Builtin(v) => v.fmt(f)?,
-            Lit(a) => a.fmt(f)?,
+            Num(a) => a.fmt(f)?,
             TextLit(a) => a.fmt(f)?,
             RecordType(a) if a.is_empty() => f.write_str("{}")?,
             RecordType(a) => fmt_list("{ ", ", ", " }", a, f, |(k, t), f| {
@@ -240,9 +240,9 @@ impl Display for Expr {
     }
 }
 
-impl Display for LitKind {
+impl Display for NumKind {
     fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        use LitKind::*;
+        use NumKind::*;
         match self {
             Bool(true) => f.write_str("True")?,
             Bool(false) => f.write_str("False")?,
diff --git a/dhall/src/tests.rs b/dhall/src/tests.rs
index a5a278c..2cd354f 100644
--- a/dhall/src/tests.rs
+++ b/dhall/src/tests.rs
@@ -10,8 +10,8 @@ use std::io::{Read, Write};
 use std::path::PathBuf;
 
 use crate::error::{ErrorKind, Result};
-use crate::syntax::binary;
-use crate::{Normalized, NormalizedExpr, Parsed, Resolved, Typed};
+use crate::syntax::{binary, Expr};
+use crate::{Normalized, Parsed, Resolved, Typed};
 
 macro_rules! assert_eq_display {
     ($left:expr, $right:expr) => {{
@@ -111,7 +111,7 @@ impl TestFile {
         env::var("UPDATE_TEST_FILES") == Ok("1".to_string())
     }
     /// Write the provided expression to the pointed file.
-    fn write_expr(&self, expr: impl Into<NormalizedExpr>) -> Result<()> {
+    fn write_expr(&self, expr: impl Into<Expr>) -> Result<()> {
         let expr = expr.into();
         let path = self.path();
         create_dir_all(path.parent().unwrap())?;
@@ -142,7 +142,7 @@ impl TestFile {
     }
 
     /// Check that the provided expression matches the file contents.
-    pub fn compare(&self, expr: impl Into<NormalizedExpr>) -> Result<()> {
+    pub fn compare(&self, expr: impl Into<Expr>) -> Result<()> {
         let expr = expr.into();
         if !self.path().is_file() {
             return self.write_expr(expr);
@@ -159,7 +159,7 @@ impl TestFile {
         Ok(())
     }
     /// Check that the provided expression matches the file contents.
-    pub fn compare_debug(&self, expr: impl Into<NormalizedExpr>) -> Result<()> {
+    pub fn compare_debug(&self, expr: impl Into<Expr>) -> Result<()> {
         let expr = expr.into();
         if !self.path().is_file() {
             return self.write_expr(expr);
@@ -176,10 +176,7 @@ impl TestFile {
         Ok(())
     }
     /// Check that the provided expression matches the file contents.
-    pub fn compare_binary(
-        &self,
-        expr: impl Into<NormalizedExpr>,
-    ) -> Result<()> {
+    pub fn compare_binary(&self, expr: impl Into<Expr>) -> Result<()> {
         let expr = expr.into();
         match self {
             TestFile::Binary(_) => {}
@@ -302,7 +299,7 @@ fn run_test(test: Test) -> Result<()> {
             expected.compare(expr)?;
         }
         ImportFailure(expr, expected) => {
-            let err = expr.parse()?.resolve().unwrap_err();
+            let err = expr.resolve().unwrap_err();
             expected.compare_ui(err)?;
         }
         TypeInferenceSuccess(expr, expected) => {
diff --git a/dhall/tests/version_numbers.rs b/dhall/tests/version_numbers.rs
new file mode 100644
index 0000000..9f1d04a
--- /dev/null
+++ b/dhall/tests/version_numbers.rs
@@ -0,0 +1,4 @@
+#[test]
+fn test_html_root_url() {
+    version_sync::assert_html_root_url_updated!("src/lib.rs");
+}