Split-off core into its own crate

11 files changed, 10 insertions, 2624 deletions

diff --git a/dhall/Cargo.toml b/dhall/Cargo.toml
index d44324a..db62d5b 100644
--- a/dhall/Cargo.toml
+++ b/dhall/Cargo.toml
@@ -3,16 +3,10 @@ name = "dhall"
 version = "0.1.0"
 authors = ["NanoTech <nanotech@nanotechcorp.net>", "Nadrieril <nadrieril@users.noreply.github.com>"]
 edition = "2018"
-build = "build.rs"
-
-[build-dependencies]
-lalrpop = "0.16.3"
 
 [dependencies]
 bytecount = "0.5.1"
 itertools = "0.8.0"
 lalrpop-util = "0.16.3"
-nom = "3.0.0"
 term-painter = "0.2.3"
-pest = { git = "https://github.com/pest-parser/pest" }
-dhall_parser = { path = "../dhall_parser" }
+dhall_core = { path = "../dhall_core" }
diff --git a/dhall/build.rs b/dhall/build.rs
deleted file mode 100644
index 946841a..0000000
--- a/dhall/build.rs
+++ /dev/null
@@ -1,6 +0,0 @@
-use lalrpop;
-
-fn main() {
-    lalrpop::process_root().unwrap();
-    println!("cargo:rerun-if-changed=src/grammar.lalrpop");
-}
diff --git a/dhall/src/core.rs b/dhall/src/core.rs
deleted file mode 100644
index 340cb04..0000000
--- a/dhall/src/core.rs
+++ /dev/null
@@ -1,1205 +0,0 @@
-#![allow(non_snake_case)]
-use std::collections::BTreeMap;
-use std::fmt::{self, Display};
-use std::path::PathBuf;
-
-/// Constants for a pure type system
-///
-/// The only axiom is:
-///
-/// ```c
-/// ⊦ Type : Kind
-/// ```
-///
-/// ... and the valid rule pairs are:
-///
-/// ```c
-/// ⊦ Type ↝ Type : Type  -- Functions from terms to terms (ordinary functions)
-/// ⊦ Kind ↝ Type : Type  -- Functions from types to terms (polymorphic functions)
-/// ⊦ Kind ↝ Kind : Kind  -- Functions from types to types (type constructors)
-/// ```
-///
-/// These are the same rule pairs as System Fω
-///
-/// Note that Dhall does not support functions from terms to types and therefore
-/// Dhall is not a dependently typed language
-///
-#[derive(Debug, Copy, Clone, PartialEq, Eq)] // (Show, Bounded, Enum)
-pub enum Const {
-    Type,
-    Kind,
-}
-
-/// Path to an external resource
-#[derive(Debug, Clone, PartialEq, Eq)] // (Eq, Ord, Show)
-pub enum Path {
-    File(PathBuf),
-    URL(String),
-}
-
-/// Label for a bound variable
-///
-/// The `String` field is the variable's name (i.e. \"`x`\").
-///
-/// The `Int` field disambiguates variables with the same name if there are
-/// multiple bound variables of the same name in scope.  Zero refers to the
-/// nearest bound variable and the index increases by one for each bound
-/// variable of the same name going outward.  The following diagram may help:
-///
-/// ```c
-///                                 +---refers to--+
-///                                 |              |
-///                                 v              |
-/// \(x : Type) -> \(y : Type) -> \(x : Type) -> x@0
-///
-///   +------------------refers to-----------------+
-///   |                                            |
-///   v                                            |
-/// \(x : Type) -> \(y : Type) -> \(x : Type) -> x@1
-/// ```
-///
-/// This `Int` behaves like a De Bruijn index in the special case where all
-/// variables have the same name.
-///
-/// You can optionally omit the index if it is `0`:
-///
-/// ```c
-///                           +refers to+
-///                           |         |
-///                           v         |
-/// \(x : *) -> \(y : *) -> \(x : *) -> x
-/// ```
-///
-/// Zero indices are omitted when pretty-printing `Var`s and non-zero indices
-/// appear as a numeric suffix.
-///
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
-pub struct V<'i>(pub &'i str, pub usize);
-
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
-pub enum BinOp {
-    /// x && y`
-    BoolAnd,
-    /// x || y`
-    BoolOr,
-    /// x == y`
-    BoolEQ,
-    /// x != y`
-    BoolNE,
-    /// x + y`
-    NaturalPlus,
-    /// x * y`
-    NaturalTimes,
-    /// x ++ y`
-    TextAppend,
-    /// x ∧ y`
-    Combine,
-    /// x //\\ y
-    CombineTypes,
-    /// x ? y
-    ImportAlt,
-    /// x // y
-    Prefer,
-    /// x # y
-    ListAppend,
-}
-
-/// Syntax tree for expressions
-#[derive(Debug, Clone, PartialEq)]
-pub enum Expr<'i, S, A> {
-    ///  `Const c                                  ~  c`
-    Const(Const),
-    ///  `Var (V x 0)                              ~  x`<br>
-    ///  `Var (V x n)                              ~  x@n`
-    Var(V<'i>),
-    ///  `Lam x     A b                            ~  λ(x : A) -> b`
-    Lam(&'i str, Box<Expr<'i, S, A>>, Box<Expr<'i, S, A>>),
-    ///  `Pi "_" A B                               ~        A  -> B`
-    ///  `Pi x   A B                               ~  ∀(x : A) -> B`
-    Pi(&'i str, Box<Expr<'i, S, A>>, Box<Expr<'i, S, A>>),
-    ///  `App f A                                  ~  f A`
-    App(Box<Expr<'i, S, A>>, Box<Expr<'i, S, A>>),
-    ///  `Let x Nothing  r e  ~  let x     = r in e`
-    ///  `Let x (Just t) r e  ~  let x : t = r in e`
-    Let(
-        &'i str,
-        Option<Box<Expr<'i, S, A>>>,
-        Box<Expr<'i, S, A>>,
-        Box<Expr<'i, S, A>>,
-    ),
-    ///  `Annot x t                                ~  x : t`
-    Annot(Box<Expr<'i, S, A>>, Box<Expr<'i, S, A>>),
-    /// Built-in values
-    Builtin(Builtin),
-    // Binary operations
-    BinOp(BinOp, Box<Expr<'i, S, A>>, Box<Expr<'i, S, A>>),
-    ///  `BoolLit b                                ~  b`
-    BoolLit(bool),
-    ///  `BoolIf x y z                             ~  if x then y else z`
-    BoolIf(
-        Box<Expr<'i, S, A>>,
-        Box<Expr<'i, S, A>>,
-        Box<Expr<'i, S, A>>,
-    ),
-    ///  `NaturalLit n                             ~  +n`
-    NaturalLit(Natural),
-    ///  `IntegerLit n                             ~  n`
-    IntegerLit(Integer),
-    ///  `DoubleLit n                              ~  n`
-    DoubleLit(Double),
-    ///  `TextLit t                                ~  t`
-    TextLit(Builder),
-    ///  `ListLit t [x, y, z]                      ~  [x, y, z] : List t`
-    ListLit(Option<Box<Expr<'i, S, A>>>, Vec<Expr<'i, S, A>>),
-    ///  `OptionalLit t [e]                        ~  [e] : Optional t`
-    ///  `OptionalLit t []                         ~  []  : Optional t`
-    OptionalLit(Option<Box<Expr<'i, S, A>>>, Vec<Expr<'i, S, A>>),
-    ///  `Record            [(k1, t1), (k2, t2)]   ~  { k1 : t1, k2 : t1 }`
-    Record(BTreeMap<&'i str, Expr<'i, S, A>>),
-    ///  `RecordLit         [(k1, v1), (k2, v2)]   ~  { k1 = v1, k2 = v2 }`
-    RecordLit(BTreeMap<&'i str, Expr<'i, S, A>>),
-    ///  `Union             [(k1, t1), (k2, t2)]   ~  < k1 : t1, k2 : t2 >`
-    Union(BTreeMap<&'i str, Expr<'i, S, A>>),
-    ///  `UnionLit (k1, v1) [(k2, t2), (k3, t3)]   ~  < k1 = t1, k2 : t2, k3 : t3 >`
-    UnionLit(
-        &'i str,
-        Box<Expr<'i, S, A>>,
-        BTreeMap<&'i str, Expr<'i, S, A>>,
-    ),
-    ///  `Merge x y t                              ~  merge x y : t`
-    Merge(
-        Box<Expr<'i, S, A>>,
-        Box<Expr<'i, S, A>>,
-        Option<Box<Expr<'i, S, A>>>,
-    ),
-    ///  `Field e x                                ~  e.x`
-    Field(Box<Expr<'i, S, A>>, &'i str),
-    ///  `Note S x                                 ~  e`
-    Note(S, Box<Expr<'i, S, A>>),
-    ///  `Embed path                               ~  path`
-    Embed(A),
-
-    FailedParse(String, Vec<Expr<'i, S, A>>),
-}
-
-/// Built-ins
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
-pub enum Builtin {
-    Bool,
-    Natural,
-    Integer,
-    Double,
-    Text,
-    List,
-    Optional,
-    NaturalBuild,
-    NaturalFold,
-    NaturalIsZero,
-    NaturalEven,
-    NaturalOdd,
-    NaturalToInteger,
-    NaturalShow,
-    IntegerToDouble,
-    IntegerShow,
-    DoubleShow,
-    ListBuild,
-    ListFold,
-    ListLength,
-    ListHead,
-    ListLast,
-    ListIndexed,
-    ListReverse,
-    OptionalFold,
-    OptionalBuild,
-    TextShow,
-}
-
-impl<'i> From<&'i str> for V<'i> {
-    fn from(s: &'i str) -> Self {
-        V(s, 0)
-    }
-}
-
-impl<'i, S, A> From<&'i str> for Expr<'i, S, A> {
-    fn from(s: &'i str) -> Self {
-        Expr::Var(s.into())
-    }
-}
-
-impl<'i, S, A> From<Builtin> for Expr<'i, S, A> {
-    fn from(t: Builtin) -> Self {
-        Expr::Builtin(t)
-    }
-}
-
-impl<'i, S, A> Expr<'i, S, A> {
-    fn bool_lit(&self) -> Option<bool> {
-        match *self {
-            Expr::BoolLit(v) => Some(v),
-            _ => None,
-        }
-    }
-
-    fn natural_lit(&self) -> Option<usize> {
-        match *self {
-            Expr::NaturalLit(v) => Some(v),
-            _ => None,
-        }
-    }
-
-    fn text_lit(&self) -> Option<String> {
-        match *self {
-            Expr::TextLit(ref t) => Some(t.clone()), // FIXME?
-            _ => None,
-        }
-    }
-}
-
-//  There is a one-to-one correspondence between the formatters in this section
-//  and the grammar in grammar.lalrpop.  Each formatter is named after the
-//  corresponding grammar rule and the relationship between formatters exactly matches
-//  the relationship between grammar rules.  This leads to the nice emergent property
-//  of automatically getting all the parentheses and precedences right.
-//
-//  This approach has one major disadvantage: you can get an infinite loop if
-//  you add a new constructor to the syntax tree without adding a matching
-//  case the corresponding builder.
-
-impl<'i, S, A: Display> Display for Expr<'i, S, A> {
-    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        // buildExprA
-        use crate::Expr::*;
-        match self {
-            &Annot(ref a, ref b) => {
-                a.fmt_b(f)?;
-                write!(f, " : ")?;
-                b.fmt(f)
-            }
-            &Note(_, ref b) => b.fmt(f),
-            a => a.fmt_b(f),
-        }
-    }
-}
-
-impl<'i, S, A: Display> Expr<'i, S, A> {
-    fn fmt_b(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        use crate::Expr::*;
-        match self {
-            &Lam(a, ref b, ref c) => {
-                write!(f, "λ({} : ", a)?;
-                b.fmt(f)?;
-                write!(f, ") → ")?;
-                c.fmt_b(f)
-            }
-            &BoolIf(ref a, ref b, ref c) => {
-                write!(f, "if ")?;
-                a.fmt(f)?;
-                write!(f, " then ")?;
-                b.fmt_b(f)?;
-                write!(f, " else ")?;
-                c.fmt_c(f)
-            }
-            &Pi("_", ref b, ref c) => {
-                b.fmt_c(f)?;
-                write!(f, " → ")?;
-                c.fmt_b(f)
-            }
-            &Pi(a, ref b, ref c) => {
-                write!(f, "∀({} : ", a)?;
-                b.fmt(f)?;
-                write!(f, ") → ")?;
-                c.fmt_b(f)
-            }
-            &Let(a, None, ref c, ref d) => {
-                write!(f, "let {} = ", a)?;
-                c.fmt(f)?;
-                write!(f, ") → ")?;
-                d.fmt_b(f)
-            }
-            &Let(a, Some(ref b), ref c, ref d) => {
-                write!(f, "let {} : ", a)?;
-                b.fmt(f)?;
-                write!(f, " = ")?;
-                c.fmt(f)?;
-                write!(f, ") → ")?;
-                d.fmt_b(f)
-            }
-            &ListLit(ref t, ref es) => {
-                fmt_list("[", "]", es, f, |e, f| e.fmt(f))?;
-                match t {
-                    Some(t) => {
-                        write!(f, " : List ")?;
-                        t.fmt_e(f)?
-                    }
-                    None => {}
-                }
-                Ok(())
-            }
-            &OptionalLit(ref t, ref es) => {
-                fmt_list("[", "]", es, f, |e, f| e.fmt(f))?;
-                match t {
-                    Some(t) => {
-                        write!(f, " : Optional ")?;
-                        t.fmt_e(f)?
-                    }
-                    None => {}
-                }
-                Ok(())
-            }
-            &Merge(ref a, ref b, ref c) => {
-                write!(f, "merge ")?;
-                a.fmt_e(f)?;
-                write!(f, " ")?;
-                b.fmt_e(f)?;
-                match c {
-                    Some(c) => {
-                        write!(f, " : ")?;
-                        c.fmt_d(f)?
-                    }
-                    None => {}
-                }
-                Ok(())
-            }
-            &Note(_, ref b) => b.fmt_b(f),
-            a => a.fmt_c(f),
-        }
-    }
-
-    fn fmt_c(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        use crate::BinOp::*;
-        use crate::Expr::*;
-        match self {
-            // FIXME precedence
-            &BinOp(BoolOr, ref a, ref b) => {
-                a.fmt_d(f)?;
-                f.write_str(" || ")?;
-                b.fmt_c(f)
-            }
-            &BinOp(TextAppend, ref a, ref b) => {
-                a.fmt_d(f)?;
-                f.write_str(" ++ ")?;
-                b.fmt_c(f)
-            }
-            &BinOp(NaturalPlus, ref a, ref b) => {
-                a.fmt_d(f)?;
-                f.write_str(" + ")?;
-                b.fmt_c(f)
-            }
-            &BinOp(BoolAnd, ref a, ref b) => {
-                a.fmt_d(f)?;
-                f.write_str(" && ")?;
-                b.fmt_c(f)
-            }
-            &BinOp(Combine, ref a, ref b) => {
-                a.fmt_d(f)?;
-                f.write_str(" ^ ")?;
-                b.fmt_c(f)
-            }
-            &BinOp(NaturalTimes, ref a, ref b) => {
-                a.fmt_d(f)?;
-                f.write_str(" * ")?;
-                b.fmt_c(f)
-            }
-            &BinOp(BoolEQ, ref a, ref b) => {
-                a.fmt_d(f)?;
-                f.write_str(" == ")?;
-                b.fmt_c(f)
-            }
-            &BinOp(BoolNE, ref a, ref b) => {
-                a.fmt_d(f)?;
-                f.write_str(" != ")?;
-                b.fmt_c(f)
-            }
-            &Note(_, ref b) => b.fmt_c(f),
-            a => a.fmt_d(f),
-        }
-    }
-
-    fn fmt_d(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        use crate::Expr::*;
-        match self {
-            &App(ref a, ref b) => {
-                a.fmt_d(f)?;
-                f.write_str(" ")?;
-                b.fmt_e(f)
-            }
-            &Note(_, ref b) => b.fmt_d(f),
-            a => a.fmt_e(f),
-        }
-    }
-
-    fn fmt_e(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        use crate::Expr::*;
-        match self {
-            &Field(ref a, b) => {
-                a.fmt_e(f)?;
-                write!(f, ".{}", b)
-            }
-            &Note(_, ref b) => b.fmt_e(f),
-            a => a.fmt_f(f),
-        }
-    }
-
-    fn fmt_f(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        use crate::Expr::*;
-        match self {
-            &Var(a) => a.fmt(f),
-            &Const(k) => k.fmt(f),
-            &Builtin(v) => v.fmt(f),
-            &BoolLit(true) => f.write_str("True"),
-            &BoolLit(false) => f.write_str("False"),
-            &IntegerLit(a) => a.fmt(f),
-            &NaturalLit(a) => {
-                f.write_str("+")?;
-                a.fmt(f)
-            }
-            &DoubleLit(a) => a.fmt(f),
-            &TextLit(ref a) => <String as fmt::Debug>::fmt(a, f), // FIXME Format with Haskell escapes
-            &Record(ref a) if a.is_empty() => f.write_str("{}"),
-            &Record(ref a) => fmt_list("{ ", " }", a, f, |(k, t), f| {
-                write!(f, "{} : {}", k, t)
-            }),
-            &RecordLit(ref a) if a.is_empty() => f.write_str("{=}"),
-            &RecordLit(ref a) => fmt_list("{ ", " }", a, f, |(k, v), f| {
-                write!(f, "{} = {}", k, v)
-            }),
-            &Union(ref _a) => f.write_str("Union"),
-            &UnionLit(_a, ref _b, ref _c) => f.write_str("UnionLit"),
-            &Embed(ref a) => a.fmt(f),
-            &Note(_, ref b) => b.fmt_f(f),
-            a => write!(f, "({})", a),
-        }
-    }
-}
-
-fn fmt_list<T, I, F>(
-    open: &str,
-    close: &str,
-    it: I,
-    f: &mut fmt::Formatter,
-    func: F,
-) -> Result<(), fmt::Error>
-where
-    I: IntoIterator<Item = T>,
-    F: Fn(T, &mut fmt::Formatter) -> Result<(), fmt::Error>,
-{
-    f.write_str(open)?;
-    for (i, x) in it.into_iter().enumerate() {
-        if i > 0 {
-            f.write_str(", ")?;
-        }
-        func(x, f)?;
-    }
-    f.write_str(close)
-}
-
-impl Display for Const {
-    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        <Self as fmt::Debug>::fmt(self, f)
-    }
-}
-
-impl Display for Builtin {
-    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        use crate::Builtin::*;
-        f.write_str(match *self {
-            Bool => "Bool",
-            Natural => "Natural",
-            Integer => "Integer",
-            Double => "Double",
-            Text => "Text",
-            List => "List",
-            Optional => "Optional",
-            NaturalBuild => "Natural/build",
-            NaturalFold => "Natural/fold",
-            NaturalIsZero => "Natural/isZero",
-            NaturalEven => "Natural/even",
-            NaturalOdd => "Natural/odd",
-            NaturalToInteger => "Natural/toInteger",
-            NaturalShow => "Natural/show",
-            IntegerToDouble => "Integer/toDouble",
-            IntegerShow => "Integer/show",
-            DoubleShow => "Double/show",
-            ListBuild => "List/build",
-            ListFold => "List/fold",
-            ListLength => "List/length",
-            ListHead => "List/head",
-            ListLast => "List/last",
-            ListIndexed => "List/indexed",
-            ListReverse => "List/reverse",
-            OptionalFold => "Optional/fold",
-            OptionalBuild => "Optional/build",
-            TextShow => "Text/show",
-        })
-    }
-}
-
-impl Builtin {
-    pub fn parse(s: &str) -> Option<Self> {
-        use self::Builtin::*;
-        match s {
-            "Bool" => Some(Bool),
-            "Natural" => Some(Natural),
-            "Integer" => Some(Integer),
-            "Double" => Some(Double),
-            "Text" => Some(Text),
-            "List" => Some(List),
-            "Optional" => Some(Optional),
-            "Natural/build" => Some(NaturalBuild),
-            "Natural/fold" => Some(NaturalFold),
-            "Natural/isZero" => Some(NaturalIsZero),
-            "Natural/even" => Some(NaturalEven),
-            "Natural/odd" => Some(NaturalOdd),
-            "Natural/toInteger" => Some(NaturalToInteger),
-            "Natural/show" => Some(NaturalShow),
-            "Integer/toDouble" => Some(IntegerToDouble),
-            "Integer/show" => Some(IntegerShow),
-            "Double/show" => Some(DoubleShow),
-            "List/build" => Some(ListBuild),
-            "List/fold" => Some(ListFold),
-            "List/length" => Some(ListLength),
-            "List/head" => Some(ListHead),
-            "List/last" => Some(ListLast),
-            "List/indexed" => Some(ListIndexed),
-            "List/reverse" => Some(ListReverse),
-            "Optional/fold" => Some(OptionalFold),
-            "Optional/build" => Some(OptionalBuild),
-            "Text/show" => Some(TextShow),
-            _ => None,
-        }
-    }
-}
-
-impl<'i> Display for V<'i> {
-    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        let V(x, n) = *self;
-        f.write_str(x)?;
-        if n != 0 {
-            write!(f, "@{}", n)?;
-        }
-        Ok(())
-    }
-}
-
-pub fn pi<'i, S, A, Name, Et, Ev>(
-    var: Name,
-    ty: Et,
-    value: Ev,
-) -> Expr<'i, S, A>
-where
-    Name: Into<&'i str>,
-    Et: Into<Expr<'i, S, A>>,
-    Ev: Into<Expr<'i, S, A>>,
-{
-    Expr::Pi(var.into(), bx(ty.into()), bx(value.into()))
-}
-
-pub fn app<'i, S, A, Ef, Ex>(f: Ef, x: Ex) -> Expr<'i, S, A>
-where
-    Ef: Into<Expr<'i, S, A>>,
-    Ex: Into<Expr<'i, S, A>>,
-{
-    Expr::App(bx(f.into()), bx(x.into()))
-}
-
-pub type Builder = String;
-pub type Double = f64;
-pub type Int = isize;
-pub type Integer = isize;
-pub type Natural = usize;
-
-/// A void type
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
-pub enum X {}
-
-impl Display for X {
-    fn fmt(&self, _: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        match *self {}
-    }
-}
-
-pub fn bx<T>(x: T) -> Box<T> {
-    Box::new(x)
-}
-
-fn add_ui(u: usize, i: isize) -> usize {
-    if i < 0 {
-        u.checked_sub(i.checked_neg().unwrap() as usize).unwrap()
-    } else {
-        u.checked_add(i as usize).unwrap()
-    }
-}
-
-fn map_record_value<'a, I, K, V, U, F>(it: I, f: F) -> BTreeMap<K, U>
-where
-    I: IntoIterator<Item = (&'a K, &'a V)>,
-    K: Eq + Ord + Copy + 'a,
-    V: 'a,
-    F: Fn(&V) -> U,
-{
-    it.into_iter().map(|(&k, v)| (k, f(v))).collect()
-}
-
-fn map_op2<T, U, V, F, G>(f: F, g: G, a: T, b: T) -> V
-where
-    F: FnOnce(U, U) -> V,
-    G: Fn(T) -> U,
-{
-    f(g(a), g(b))
-}
-
-/// `shift` is used by both normalization and type-checking to avoid variable
-/// capture by shifting variable indices
-///
-/// For example, suppose that you were to normalize the following expression:
-///
-/// ```c
-/// λ(a : Type) → λ(x : a) → (λ(y : a) → λ(x : a) → y) x
-/// ```
-///
-/// If you were to substitute `y` with `x` without shifting any variable
-/// indices, then you would get the following incorrect result:
-///
-/// ```c
-/// λ(a : Type) → λ(x : a) → λ(x : a) → x  -- Incorrect normalized form
-/// ```
-///
-/// In order to substitute `x` in place of `y` we need to `shift` `x` by `1` in
-/// order to avoid being misinterpreted as the `x` bound by the innermost
-/// lambda.  If we perform that `shift` then we get the correct result:
-///
-/// ```c
-/// λ(a : Type) → λ(x : a) → λ(x : a) → x@1
-/// ```
-///
-/// As a more worked example, suppose that you were to normalize the following
-/// expression:
-///
-/// ```c
-///     λ(a : Type)
-/// →   λ(f : a → a → a)
-/// →   λ(x : a)
-/// →   λ(x : a)
-/// →   (λ(x : a) → f x x@1) x@1
-/// ```
-///
-/// The correct normalized result would be:
-///
-/// ```c
-///     λ(a : Type)
-/// →   λ(f : a → a → a)
-/// →   λ(x : a)
-/// →   λ(x : a)
-/// →   f x@1 x
-/// ```
-///
-/// The above example illustrates how we need to both increase and decrease
-/// variable indices as part of substitution:
-///
-/// * We need to increase the index of the outer `x\@1` to `x\@2` before we
-///   substitute it into the body of the innermost lambda expression in order
-///   to avoid variable capture.  This substitution changes the body of the
-///   lambda expression to `(f x\@2 x\@1)`
-///
-/// * We then remove the innermost lambda and therefore decrease the indices of
-///   both `x`s in `(f x\@2 x\@1)` to `(f x\@1 x)` in order to reflect that one
-///   less `x` variable is now bound within that scope
-///
-/// Formally, `(shift d (V x n) e)` modifies the expression `e` by adding `d` to
-/// the indices of all variables named `x` whose indices are greater than
-/// `(n + m)`, where `m` is the number of bound variables of the same name
-/// within that scope
-///
-/// In practice, `d` is always `1` or `-1` because we either:
-///
-/// * increment variables by `1` to avoid variable capture during substitution
-/// * decrement variables by `1` when deleting lambdas after substitution
-///
-/// `n` starts off at `0` when substitution begins and increments every time we
-/// descend into a lambda or let expression that binds a variable of the same
-/// name in order to avoid shifting the bound variables by mistake.
-///
-pub fn shift<'i, S, T, A: Clone>(
-    d: isize,
-    v: V,
-    e: &Expr<'i, S, A>,
-) -> Expr<'i, T, A> {
-    use crate::Expr::*;
-    let V(x, n) = v;
-    match *e {
-        Const(a) => Const(a),
-        Var(V(x2, n2)) => {
-            let n3 = if x == x2 && n <= n2 {
-                add_ui(n2, d)
-            } else {
-                n2
-            };
-            Var(V(x2, n3))
-        }
-        Lam(x2, ref tA, ref b) => {
-            let n2 = if x == x2 { n + 1 } else { n };
-            let tA2 = shift(d, V(x, n), tA);
-            let b2 = shift(d, V(x, n2), b);
-            Lam(x2, bx(tA2), bx(b2))
-        }
-        Pi(x2, ref tA, ref tB) => {
-            let n2 = if x == x2 { n + 1 } else { n };
-            let tA2 = shift(d, V(x, n), tA);
-            let tB2 = shift(d, V(x, n2), tB);
-            pi(x2, tA2, tB2)
-        }
-        App(ref f, ref a) => app(shift(d, v, f), shift(d, v, a)),
-        Let(f, ref mt, ref r, ref e) => {
-            let n2 = if x == f { n + 1 } else { n };
-            let e2 = shift(d, V(x, n2), e);
-            let mt2 = mt.as_ref().map(|t| bx(shift(d, V(x, n), t)));
-            let r2 = shift(d, V(x, n), r);
-            Let(f, mt2, bx(r2), bx(e2))
-        }
-        Annot(ref a, ref b) => shift_op2(Annot, d, v, a, b),
-        Builtin(v) => Builtin(v),
-        BoolLit(a) => BoolLit(a),
-        BinOp(o, ref a, ref b) => shift_op2(|x, y| BinOp(o, x, y), d, v, a, b),
-        BoolIf(ref a, ref b, ref c) => {
-            BoolIf(bx(shift(d, v, a)), bx(shift(d, v, b)), bx(shift(d, v, c)))
-        }
-        NaturalLit(a) => NaturalLit(a),
-        IntegerLit(a) => IntegerLit(a),
-        DoubleLit(a) => DoubleLit(a),
-        TextLit(ref a) => TextLit(a.clone()),
-        ListLit(ref t, ref es) => ListLit(
-            t.as_ref().map(|t| bx(shift(d, v, t))),
-            es.iter().map(|e| shift(d, v, e)).collect(),
-        ),
-        OptionalLit(ref t, ref es) => OptionalLit(
-            t.as_ref().map(|t| bx(shift(d, v, t))),
-            es.iter().map(|e| shift(d, v, e)).collect(),
-        ),
-        Record(ref a) => Record(map_record_value(a, |val| shift(d, v, val))),
-        RecordLit(ref a) => {
-            RecordLit(map_record_value(a, |val| shift(d, v, val)))
-        }
-        Union(ref a) => Union(map_record_value(a, |val| shift(d, v, val))),
-        UnionLit(k, ref uv, ref a) => UnionLit(
-            k,
-            bx(shift(d, v, uv)),
-            map_record_value(a, |val| shift(d, v, val)),
-        ),
-        Merge(ref a, ref b, ref c) => Merge(
-            bx(shift(d, v, a)),
-            bx(shift(d, v, b)),
-            c.as_ref().map(|c| bx(shift(d, v, c))),
-        ),
-        Field(ref a, b) => Field(bx(shift(d, v, a)), b),
-        Note(_, ref b) => shift(d, v, b),
-        // The Dhall compiler enforces that all embedded values are closed expressions
-        // and `shift` does nothing to a closed expression
-        Embed(ref p) => Embed(p.clone()),
-        _ => panic!(),
-    }
-}
-
-fn shift_op2<'i, S, T, A, F>(
-    f: F,
-    d: isize,
-    v: V,
-    a: &Expr<'i, S, A>,
-    b: &Expr<'i, S, A>,
-) -> Expr<'i, T, A>
-where
-    F: FnOnce(Box<Expr<'i, T, A>>, Box<Expr<'i, T, A>>) -> Expr<'i, T, A>,
-    A: Clone,
-{
-    map_op2(f, |x| bx(shift(d, v, x)), a, b)
-}
-
-/// Substitute all occurrences of a variable with an expression
-///
-/// ```c
-/// subst x C B  ~  B[x := C]
-/// ```
-///
-pub fn subst<'i, S, T, A>(
-    v: V<'i>,
-    e: &Expr<'i, S, A>,
-    b: &Expr<'i, T, A>,
-) -> Expr<'i, S, A>
-where
-    S: Clone,
-    A: Clone,
-{
-    use crate::Expr::*;
-    let V(x, n) = v;
-    match *b {
-        Const(a) => Const(a),
-        Lam(y, ref tA, ref b) => {
-            let n2 = if x == y { n + 1 } else { n };
-            let b2 = subst(V(x, n2), &shift(1, V(y, 0), e), b);
-            let tA2 = subst(V(x, n), e, tA);
-            Lam(y, bx(tA2), bx(b2))
-        }
-        Pi(y, ref tA, ref tB) => {
-            let n2 = if x == y { n + 1 } else { n };
-            let tB2 = subst(V(x, n2), &shift(1, V(y, 0), e), tB);
-            let tA2 = subst(V(x, n), e, tA);
-            pi(y, tA2, tB2)
-        }
-        App(ref f, ref a) => {
-            let f2 = subst(v, e, f);
-            let a2 = subst(v, e, a);
-            app(f2, a2)
-        }
-        Var(v2) => {
-            if v == v2 {
-                e.clone()
-            } else {
-                Var(v2)
-            }
-        }
-        Let(f, ref mt, ref r, ref b) => {
-            let n2 = if x == f { n + 1 } else { n };
-            let b2 = subst(V(x, n2), &shift(1, V(f, 0), e), b);
-            let mt2 = mt.as_ref().map(|t| bx(subst(V(x, n), e, t)));
-            let r2 = subst(V(x, n), e, r);
-            Let(f, mt2, bx(r2), bx(b2))
-        }
-        Annot(ref a, ref b) => subst_op2(Annot, v, e, a, b),
-        Builtin(v) => Builtin(v),
-        BoolLit(a) => BoolLit(a),
-        BinOp(o, ref a, ref b) => subst_op2(|x, y| BinOp(o, x, y), v, e, a, b),
-        BoolIf(ref a, ref b, ref c) => {
-            BoolIf(bx(subst(v, e, a)), bx(subst(v, e, b)), bx(subst(v, e, c)))
-        }
-        NaturalLit(a) => NaturalLit(a),
-        IntegerLit(a) => IntegerLit(a),
-        DoubleLit(a) => DoubleLit(a),
-        TextLit(ref a) => TextLit(a.clone()),
-        ListLit(ref a, ref b) => {
-            let a2 = a.as_ref().map(|a| bx(subst(v, e, a)));
-            let b2 = b.iter().map(|be| subst(v, e, be)).collect();
-            ListLit(a2, b2)
-        }
-        OptionalLit(ref a, ref b) => {
-            let a2 = a.as_ref().map(|a| bx(subst(v, e, a)));
-            let b2 = b.iter().map(|be| subst(v, e, be)).collect();
-            OptionalLit(a2, b2)
-        }
-        Record(ref kts) => Record(map_record_value(kts, |t| subst(v, e, t))),
-        RecordLit(ref kvs) => {
-            RecordLit(map_record_value(kvs, |val| subst(v, e, val)))
-        }
-        Union(ref kts) => Union(map_record_value(kts, |t| subst(v, e, t))),
-        UnionLit(k, ref uv, ref kvs) => UnionLit(
-            k,
-            bx(subst(v, e, uv)),
-            map_record_value(kvs, |val| subst(v, e, val)),
-        ),
-        Merge(ref a, ref b, ref c) => Merge(
-            bx(subst(v, e, a)),
-            bx(subst(v, e, b)),
-            c.as_ref().map(|c| bx(subst(v, e, c))),
-        ),
-        Field(ref a, b) => Field(bx(subst(v, e, a)), b),
-        Note(_, ref b) => subst(v, e, b),
-        Embed(ref p) => Embed(p.clone()),
-        _ => panic!(),
-    }
-}
-
-fn subst_op2<'i, S, T, A, F>(
-    f: F,
-    v: V<'i>,
-    e: &Expr<'i, S, A>,
-    a: &Expr<'i, T, A>,
-    b: &Expr<'i, T, A>,
-) -> Expr<'i, S, A>
-where
-    F: FnOnce(Box<Expr<'i, S, A>>, Box<Expr<'i, S, A>>) -> Expr<'i, S, A>,
-    S: Clone,
-    A: Clone,
-{
-    map_op2(f, |x| bx(subst(v, e, x)), a, b)
-}
-
-/// Reduce an expression to its normal form, performing beta reduction
-///
-/// `normalize` does not type-check the expression.  You may want to type-check
-/// expressions before normalizing them since normalization can convert an
-/// ill-typed expression into a well-typed expression.
-///
-/// However, `normalize` will not fail if the expression is ill-typed and will
-/// leave ill-typed sub-expressions unevaluated.
-///
-pub fn normalize<'i, S, T, A>(e: &Expr<'i, S, A>) -> Expr<'i, T, A>
-where
-    S: Clone + fmt::Debug,
-    T: Clone + fmt::Debug,
-    A: Clone + fmt::Debug,
-{
-    use crate::BinOp::*;
-    use crate::Builtin::*;
-    use crate::Expr::*;
-    match *e {
-        Const(k) => Const(k),
-        Var(v) => Var(v),
-        Lam(x, ref tA, ref b) => {
-            let tA2 = normalize(tA);
-            let b2 = normalize(b);
-            Lam(x, bx(tA2), bx(b2))
-        }
-        Pi(x, ref tA, ref tB) => {
-            let tA2 = normalize(tA);
-            let tB2 = normalize(tB);
-            pi(x, tA2, tB2)
-        }
-        App(ref f, ref a) => match normalize::<S, T, A>(f) {
-            Lam(x, _A, b) => {
-                // Beta reduce
-                let vx0 = V(x, 0);
-                let a2 = shift::<S, S, A>(1, vx0, a);
-                let b2 = subst::<S, T, A>(vx0, &a2, &b);
-                let b3 = shift::<S, T, A>(-1, vx0, &b2);
-                normalize(&b3)
-            }
-            f2 => match (f2, normalize::<S, T, A>(a)) {
-                // fold/build fusion for `List`
-                (App(box Builtin(ListBuild), _), App(box App(box Builtin(ListFold), _), box e2)) |
-                (App(box Builtin(ListFold), _), App(box App(box Builtin(ListBuild), _), box e2)) |
-
-                // fold/build fusion for `Natural`
-                (Builtin(NaturalBuild), App(box Builtin(NaturalFold), box e2)) |
-                (Builtin(NaturalFold), App(box Builtin(NaturalBuild), box e2)) => normalize(&e2),
-
-            /*
-                App (App (App (App NaturalFold (NaturalLit n0)) _) succ') zero ->
-                    normalize (go n0)
-                  where
-                    go !0 = zero
-                    go !n = App succ' (go (n - 1))
-                App NaturalBuild k
-                    | check     -> NaturalLit n
-                    | otherwise -> App f' a'
-                  where
-                    labeled =
-                        normalize (App (App (App k Natural) "Succ") "Zero")
-
-                    n = go 0 labeled
-                      where
-                        go !m (App (Var "Succ") e') = go (m + 1) e'
-                        go !m (Var "Zero")          = m
-                        go !_  _                    = internalError text
-                    check = go labeled
-                      where
-                        go (App (Var "Succ") e') = go e'
-                        go (Var "Zero")          = True
-                        go  _                    = False
-                        */
-                (Builtin(NaturalIsZero), NaturalLit(n)) => BoolLit(n == 0),
-                (Builtin(NaturalEven), NaturalLit(n)) => BoolLit(n % 2 == 0),
-                (Builtin(NaturalOdd), NaturalLit(n)) => BoolLit(n % 2 != 0),
-                (Builtin(NaturalToInteger), NaturalLit(n)) => IntegerLit(n as isize),
-                (Builtin(NaturalShow), NaturalLit(n)) => TextLit(n.to_string()),
-                (App(f@box Builtin(ListBuild), box t), k) => {
-                        let labeled =
-                            normalize::<_, T, _>(&app(app(app(k.clone(), app(
-                                Builtin(self::Builtin::List), t.clone())), "Cons"), "Nil"));
-
-                        fn list_to_vector<'i, S, A>(v: &mut Vec<Expr<'i, S, A>>, e: Expr<'i, S, A>)
-                            where S: Clone, A: Clone
-                        {
-                            match e {
-                                App(box App(box Var(V("Cons", _)), box x), box e2) => {
-                                    v.push(x);
-                                    list_to_vector(v, e2)
-                                }
-                                Var(V("Nil", _)) => {}
-                                _ => panic!("internalError list_to_vector"),
-                            }
-                        }
-                        fn check<S, A>(e: &Expr<S, A>) -> bool {
-                            match *e {
-                                App(box App(box Var(V("Cons", _)), _), ref e2) => check(e2),
-                                Var(V("Nil", _)) => true,
-                                _ => false,
-                            }
-                        }
-
-                        if check(&labeled) {
-                            let mut v = vec![];
-                            list_to_vector(&mut v, labeled);
-                            ListLit(Some(bx(t)), v)
-                        } else {
-                            app(App(f, bx(t)), k)
-                        }
-                    }
-                (App(box App(box App(box App(box Builtin(ListFold), _), box ListLit(_, xs)), _), cons), nil) => {
-                    let e2: Expr<_, _> = xs.into_iter().rev().fold(nil, |y, ys| // foldr
-                        App(bx(App(cons.clone(), bx(y))), bx(ys))
-                    );
-                    normalize(&e2)
-                }
-                (App(f, x_), ListLit(t, ys)) => match *f {
-                    Builtin(ListLength) =>
-                        NaturalLit(ys.len()),
-                    Builtin(ListHead) =>
-                        normalize(&OptionalLit(t, ys.into_iter().take(1).collect())),
-                    Builtin(ListLast) =>
-                        normalize(&OptionalLit(t, ys.into_iter().last().into_iter().collect())),
-                    Builtin(ListReverse) => {
-                        let mut xs = ys;
-                        xs.reverse();
-                        normalize(&ListLit(t, xs))
-                    }
-                    _ => app(App(f, x_), ListLit(t, ys)),
-                },
-                /*
-                App (App ListIndexed _) (ListLit t xs) ->
-                    normalize (ListLit t' (fmap adapt (Data.Vector.indexed xs)))
-                  where
-                    t' = Record (Data.Map.fromList kts)
-                      where
-                        kts = [ ("index", Natural)
-                              , ("value", t)
-                              ]
-                    adapt (n, x) = RecordLit (Data.Map.fromList kvs)
-                      where
-                        kvs = [ ("index", NaturalLit (fromIntegral n))
-                              , ("value", x)
-                              ]
-            */
-                (App(box App(box App(box App(box Builtin(OptionalFold), _), box OptionalLit(_, xs)), _), just), nothing) => {
-                    let e2: Expr<_, _> = xs.into_iter().fold(nothing, |y, _|
-                        App(just.clone(), bx(y))
-                    );
-                    normalize(&e2)
-                }
-                (App(box Builtin(OptionalBuild), _), App(box App(box Builtin(OptionalFold), _), b)) => {
-                    normalize(&b)
-                }
-                (App(box Builtin(OptionalBuild), a0), g) => {
-                    let e2: Expr<_, _> = app(app(app(g,
-                        App(bx(Builtin(Optional)), a0.clone())),
-                            Lam("x", a0.clone(),
-                                bx(OptionalLit(Some(a0.clone()), vec![Var(V("x", 0))])))),
-                            OptionalLit(Some(a0), vec![]));
-                    normalize(&e2)
-                }
-                (f2, a2) => app(f2, a2),
-            },
-        },
-        Let(f, _, ref r, ref b) => {
-            let r2 = shift::<_, S, _>(1, V(f, 0), r);
-            let b2 = subst(V(f, 0), &r2, b);
-            let b3 = shift::<_, T, _>(-1, V(f, 0), &b2);
-            normalize(&b3)
-        }
-        Annot(ref x, _) => normalize(x),
-        Builtin(v) => Builtin(v),
-        BoolLit(b) => BoolLit(b),
-        BinOp(BoolAnd, ref x, ref y) => with_binop(
-            BoolAnd,
-            Expr::bool_lit,
-            |xn, yn| BoolLit(xn && yn),
-            normalize(x),
-            normalize(y),
-        ),
-        BinOp(BoolOr, ref x, ref y) => with_binop(
-            BoolOr,
-            Expr::bool_lit,
-            |xn, yn| BoolLit(xn || yn),
-            normalize(x),
-            normalize(y),
-        ),
-        BinOp(BoolEQ, ref x, ref y) => with_binop(
-            BoolEQ,
-            Expr::bool_lit,
-            |xn, yn| BoolLit(xn == yn),
-            normalize(x),
-            normalize(y),
-        ),
-        BinOp(BoolNE, ref x, ref y) => with_binop(
-            BoolNE,
-            Expr::bool_lit,
-            |xn, yn| BoolLit(xn != yn),
-            normalize(x),
-            normalize(y),
-        ),
-        BoolIf(ref b, ref t, ref f) => match normalize(b) {
-            BoolLit(true) => normalize(t),
-            BoolLit(false) => normalize(f),
-            b2 => BoolIf(bx(b2), bx(normalize(t)), bx(normalize(f))),
-        },
-        NaturalLit(n) => NaturalLit(n),
-        BinOp(NaturalPlus, ref x, ref y) => with_binop(
-            NaturalPlus,
-            Expr::natural_lit,
-            |xn, yn| NaturalLit(xn + yn),
-            normalize(x),
-            normalize(y),
-        ),
-        BinOp(NaturalTimes, ref x, ref y) => with_binop(
-            NaturalTimes,
-            Expr::natural_lit,
-            |xn, yn| NaturalLit(xn * yn),
-            normalize(x),
-            normalize(y),
-        ),
-        IntegerLit(n) => IntegerLit(n),
-        DoubleLit(n) => DoubleLit(n),
-        TextLit(ref t) => TextLit(t.clone()),
-        BinOp(TextAppend, ref x, ref y) => with_binop(
-            TextAppend,
-            Expr::text_lit,
-            |xt, yt| TextLit(xt + &yt),
-            normalize(x),
-            normalize(y),
-        ),
-        ListLit(ref t, ref es) => {
-            let t2 = t.as_ref().map(|x| x.as_ref()).map(normalize).map(bx);
-            let es2 = es.iter().map(normalize).collect();
-            ListLit(t2, es2)
-        }
-        OptionalLit(ref t, ref es) => {
-            let t2 = t.as_ref().map(|x| x.as_ref()).map(normalize).map(bx);
-            let es2 = es.iter().map(normalize).collect();
-            OptionalLit(t2, es2)
-        }
-        Record(ref kts) => Record(map_record_value(kts, normalize)),
-        RecordLit(ref kvs) => RecordLit(map_record_value(kvs, normalize)),
-        Union(ref kts) => Union(map_record_value(kts, normalize)),
-        UnionLit(k, ref v, ref kvs) => {
-            UnionLit(k, bx(normalize(v)), map_record_value(kvs, normalize))
-        }
-        Merge(ref _x, ref _y, ref _t) => unimplemented!(),
-        Field(ref r, x) => match normalize(r) {
-            RecordLit(kvs) => match kvs.get(x) {
-                Some(r2) => normalize(r2),
-                None => {
-                    Field(bx(RecordLit(map_record_value(&kvs, normalize))), x)
-                }
-            },
-            r2 => Field(bx(r2), x),
-        },
-        Note(_, ref e) => normalize(e),
-        Embed(ref a) => Embed(a.clone()),
-        _ => unimplemented!(),
-    }
-}
-
-fn with_binop<'a, S, A, U, Get, Set>(
-    op: BinOp,
-    get: Get,
-    set: Set,
-    x: Expr<'a, S, A>,
-    y: Expr<'a, S, A>,
-) -> Expr<'a, S, A>
-where
-    Get: Fn(&Expr<'a, S, A>) -> Option<U>,
-    Set: FnOnce(U, U) -> Expr<'a, S, A>,
-{
-    if let (Some(xv), Some(yv)) = (get(&x), get(&y)) {
-        set(xv, yv)
-    } else {
-        Expr::BinOp(op, bx(x), bx(y))
-    }
-}
diff --git a/dhall/src/grammar.lalrpop b/dhall/src/grammar.lalrpop
deleted file mode 100644
index 1ffe2ff..0000000
--- a/dhall/src/grammar.lalrpop
+++ /dev/null
@@ -1,164 +0,0 @@
-use std::collections::BTreeMap;
-use std::iter;
-use std::iter::FromIterator;
-
-use crate::core;
-use crate::core::bx;
-use crate::core::Expr::*;
-use crate::core::Builtin;
-use crate::core::Builtin::*;
-use crate::core::BinOp::*;
-use crate::grammar_util::*;
-use crate::lexer::*;
-
-grammar<'input>;
-
-extern {
-    type Location = usize;
-    type Error = LexicalError;
-
-    enum Tok<'input> {
-        Pi => Tok::Pi,
-        Lambda => Tok::Lambda,
-        Combine => Tok::Combine,
-        "->" => Tok::Arrow,
-
-        Int => Tok::Integer(<isize>),
-        Nat => Tok::Natural(<usize>),
-        Text => Tok::Text(<String>),
-        Bool => Tok::Bool(<bool>),
-        Label => Tok::Identifier(<&'input str>),
-        Const => Tok::Const(<core::Const>),
-        Let => Tok::Keyword(Keyword::Let),
-        In => Tok::Keyword(Keyword::In),
-        If => Tok::Keyword(Keyword::If),
-        Then => Tok::Keyword(Keyword::Then),
-        Else => Tok::Keyword(Keyword::Else),
-        List => Tok::ListLike(ListLike::List),
-        Optional => Tok::ListLike(ListLike::Optional),
-        Builtin => Tok::Builtin(<Builtin>),
-
-        "{" => Tok::BraceL,
-        "}" => Tok::BraceR,
-        "[" => Tok::BracketL,
-        "]" => Tok::BracketR,
-        "(" => Tok::ParenL,
-        ")" => Tok::ParenR,
-        "&&" => Tok::BoolAnd,
-        "||" => Tok::BoolOr,
-        "==" => Tok::CompareEQ,
-        "!=" => Tok::CompareNE,
-        "++" => Tok::Append,
-        "*" => Tok::Times,
-        "+" => Tok::Plus,
-        "," => Tok::Comma,
-        "." => Tok::Dot,
-        ":" => Tok::Ascription,
-        "=" => Tok::Equals,
-    }
-}
-
-pub Expr: BoxExpr<'input> = { // exprA
-    ExprB,
-};
-
-ExprB: BoxExpr<'input> = {
-    Lambda "(" <Label> ":" <Expr> ")" "->" <ExprB> => bx(Lam(<>)),
-    Pi "(" <Label> ":" <Expr> ")" "->" <ExprB> => bx(Pi(<>)),
-    If <Expr> Then <ExprB> Else <ExprC> => bx(BoolIf(<>)),
-    <ExprC> "->" <ExprB> => bx(Pi("_", <>)),
-    Let <Label> <(":" <Expr>)?> "=" <Expr> In <ExprB> => bx(Let(<>)),
-    "[" <a:Elems> "]" ":" <b:ListLike> <c:ExprE> => bx(b(Some(c), a)),
-    <ExprC> ":" <Expr> => bx(Annot(<>)),
-    ExprC,
-};
-
-ListLike: ExprListFn<'input> = {
-    List => ListLit,
-    Optional => OptionalLit,
-};
-
-BoolOr: ExprOpFn<'input> = { "||" => (|x,y| BinOp(BoolOr, x, y)) };
-NaturalPlus: ExprOpFn<'input> = { "+" => (|x,y| BinOp(NaturalPlus, x, y)) };
-TextAppend: ExprOpFn<'input> = { "++" => (|x,y| BinOp(TextAppend, x, y)) };
-BoolAnd: ExprOpFn<'input> = { "&&" => (|x,y| BinOp(BoolAnd, x, y)) };
-CombineOp: ExprOpFn<'input> = { Combine => (|x,y| BinOp(Combine, x, y)) };
-NaturalTimes: ExprOpFn<'input> = { "*" => (|x,y| BinOp(NaturalTimes, x, y)) };
-BoolEQ: ExprOpFn<'input> = { "==" => (|x,y| BinOp(BoolEQ, x, y)) };
-BoolNE: ExprOpFn<'input> = { "!=" => (|x,y| BinOp(BoolNE, x, y)) };
-
-Tier<NextTier, Op>: BoxExpr<'input> = {
-    <a:NextTier> <f:Op> <b:Tier<NextTier, Op>> => bx(f(a, b)),
-    // <b:Tier<NextTier, Op>> <f:Op> <a:NextTier> => bx(f(a, b)),
-    NextTier,
-};
-
-ExprC = Tier<ExprC1, BoolOr>;
-ExprC1 = Tier<ExprC2, NaturalPlus>;
-ExprC2 = Tier<ExprC3, TextAppend>;
-ExprC3 = Tier<ExprC4, BoolAnd>;
-ExprC4 = Tier<ExprC5, CombineOp>;
-ExprC5 = Tier<ExprC6, NaturalTimes>;
-ExprC6 = Tier<ExprC7, BoolEQ>;
-ExprC7 = Tier<ExprD, BoolNE>;
-
-ExprD: BoxExpr<'input> = {
-    <v:(ExprE)+> => {
-        let mut it = v.into_iter();
-        let f = it.next().unwrap();
-        it.fold(f, |f, x| bx(App(f, x)))
-    }
-};
-
-ExprE: BoxExpr<'input> = {
-    <a:ExprF> <fields:("." <Label>)*> => {
-        fields.into_iter().fold(a, |x, f| bx(Field(x, f)))
-    },
-};
-
-ExprF: BoxExpr<'input> = {
-    Nat => bx(NaturalLit(<>)),
-    Int => bx(IntegerLit(<>)),
-    Text => bx(TextLit(<>)),
-    Label => bx(Var(core::V(<>, 0))), // FIXME support var@n syntax
-    Const => bx(Const(<>)),
-    List => bx(Builtin(List)),
-    Optional => bx(Builtin(Optional)),
-    Builtin => bx(Builtin(<>)),
-    Bool => bx(BoolLit(<>)),
-    Record,
-    RecordLit,
-    "(" <Expr> ")",
-};
-
-SepBy<S, T>: iter::Chain<::std::vec::IntoIter<T>, ::std::option::IntoIter<T>> = {
-    <v:(<T> S)*> <last:T?> => v.into_iter().chain(last.into_iter()),
-};
-
-SepBy1<S, T>: iter::Chain<::std::vec::IntoIter<T>, iter::Once<T>> = {
-    <v:(<T> S)*> <last:T> => v.into_iter().chain(iter::once(last)),
-};
-
-Elems: Vec<ParsedExpr<'input>> = {
-    <v:SepBy<",", Expr>> => {
-        v.into_iter()
-         .map(|b| *b)
-         .collect::<Vec<_>>()
-    }
-};
-
-RecordLit: BoxExpr<'input> = {
-    "{" "=" "}" => bx(RecordLit(BTreeMap::new())),
-    "{" <FieldValues> "}" => bx(RecordLit(BTreeMap::from_iter(<>))),
-};
-
-Record: BoxExpr<'input> = {
-    "{" <FieldTypes> "}" => bx(Record(BTreeMap::from_iter(<>))),
-};
-
-FieldValues = SepBy1<",", Field<"=">>;
-FieldTypes = SepBy<",", Field<":">>;
-
-Field<Sep>: (&'input str, ParsedExpr<'input>) = {
-    <a:Label> Sep <b:Expr> => (a, *b),
-};
diff --git a/dhall/src/grammar_util.rs b/dhall/src/grammar_util.rs
deleted file mode 100644
index ce73444..0000000
--- a/dhall/src/grammar_util.rs
+++ /dev/null
@@ -1,7 +0,0 @@
-use crate::core::{Expr, X};
-
-pub type ParsedExpr<'i> = Expr<'i, X, X>; // FIXME Parse paths and replace the second X with Path
-pub type BoxExpr<'i> = Box<ParsedExpr<'i>>;
-pub type ExprOpFn<'i> = fn(BoxExpr<'i>, BoxExpr<'i>) -> ParsedExpr<'i>;
-pub type ExprListFn<'i> =
-    fn(Option<BoxExpr<'i>>, Vec<ParsedExpr<'i>>) -> ParsedExpr<'i>;
diff --git a/dhall/src/lexer.rs b/dhall/src/lexer.rs
deleted file mode 100644
index 5fc0f05..0000000
--- a/dhall/src/lexer.rs
+++ /dev/null
@@ -1,394 +0,0 @@
-use nom::*;
-
-use crate::core::Builtin;
-use crate::core::Builtin::*;
-use crate::core::Const;
-
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub enum Keyword {
-    Let,
-    In,
-    If,
-    Then,
-    Else,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub enum ListLike {
-    List,
-    Optional,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub enum Tok<'i> {
-    Identifier(&'i str),
-    Keyword(Keyword),
-    Builtin(Builtin),
-    ListLike(ListLike),
-    Const(Const),
-    Bool(bool),
-    Integer(isize),
-    Natural(usize),
-    Text(String),
-
-    // Symbols
-    BraceL,
-    BraceR,
-    BracketL,
-    BracketR,
-    ParenL,
-    ParenR,
-    Arrow,
-    Lambda,
-    Pi,
-    Combine,
-    BoolAnd,
-    BoolOr,
-    CompareEQ,
-    CompareNE,
-    Append,
-    Times,
-    Plus,
-    Comma,
-    Dot,
-    Ascription,
-    Equals,
-}
-
-#[derive(Debug)]
-pub enum LexicalError {
-    Error(usize, nom::simple_errors::Err<u32>),
-    Incomplete(nom::Needed),
-}
-
-pub type Spanned<Tok, Loc, Error> = Result<(Loc, Tok, Loc), Error>;
-
-#[allow(dead_code)]
-fn is_identifier_first_char(c: char) -> bool {
-    c.is_alphabetic() || c == '_'
-}
-
-fn is_identifier_rest_char(c: char) -> bool {
-    is_identifier_first_char(c) || c.is_digit(10) || c == '/'
-}
-
-macro_rules! digits {
-    ($i:expr, $t:tt, $radix:expr) => {{
-        let r: nom::IResult<&str, $t> = map_res!(
-            $i,
-            take_while1_s!(call!(|c: char| c.is_digit($radix))),
-            |s| $t::from_str_radix(s, $radix)
-        );
-        r
-    }};
-}
-
-named!(natural<&str, usize>, digits!(usize, 10));
-named!(integral<&str, isize>, digits!(isize, 10));
-named!(integer<&str, isize>, alt!(
-    preceded!(tag!("-"), map!(integral, |i: isize| -i)) |
-    preceded!(tag!("+"), integral)
-));
-named!(boolean<&str, bool>, alt!(
-    value!(true, tag!("True")) |
-    value!(false, tag!("False"))
-));
-
-named!(identifier<&str, &str>, recognize!(preceded!(
-    take_while1_s!(is_identifier_first_char),
-    take_while_s!(is_identifier_rest_char))
-));
-
-/// Parse an identifier, ensuring a whole identifier is parsed and not just a prefix.
-macro_rules! ident_tag {
-    ($i:expr, $tag:expr) => {
-        match identifier($i) {
-            nom::IResult::Done(i, s) => {
-                if s == $tag {
-                    nom::IResult::Done(i, s)
-                } else {
-                    nom::IResult::Error(error_position!(
-                        nom::ErrorKind::Tag,
-                        $i
-                    ))
-                }
-            }
-            r => r,
-        }
-    };
-}
-
-fn string_escape_single(c: char) -> Option<&'static str> {
-    match c {
-        'n' => Some("\n"),
-        'r' => Some("\r"),
-        't' => Some("\t"),
-        '"' => Some("\""),
-        '\'' => Some("'"),
-        '\\' => Some("\\"),
-        '0' => Some("\0"),
-        'a' => Some("\x07"),
-        'b' => Some("\x08"),
-        'f' => Some("\x0c"),
-        'v' => Some("\x0b"),
-        '&' => Some(""),
-        _ => None,
-    }
-}
-
-named!(string_escape_numeric<&str, char>, map_opt!(alt!(
-    preceded!(tag!("x"), digits!(u32, 16)) |
-    preceded!(tag!("o"), digits!(u32, 8)) |
-    digits!(u32, 10)
-), ::std::char::from_u32));
-
-fn string_lit_inner(input: &str) -> nom::IResult<&str, String> {
-    use nom::ErrorKind;
-    use nom::IResult::*; ;
-    let mut s = String::new();
-    let mut cs = input.char_indices().peekable();
-    while let Some((i, c)) = cs.next() {
-        match c {
-            '"' => return nom::IResult::Done(&input[i..], s),
-            '\\' => match cs.next() {
-                Some((_, s)) if s.is_whitespace() => {
-                    while cs.peek().map(|&(_, s)| s.is_whitespace())
-                        == Some(true)
-                    {
-                        let _ = cs.next();
-                    }
-                    if cs.next().map(|p| p.1) != Some('\\') {
-                        return Error(error_position!(
-                            ErrorKind::Custom(4 /* FIXME */),
-                            input
-                        ));
-                    }
-                }
-                Some((j, ec)) => {
-                    if let Some(esc) = string_escape_single(ec) {
-                        s.push_str(esc);
-                    // FIXME Named ASCII escapes and control character escapes
-                    } else {
-                        match string_escape_numeric(&input[j..]) {
-                            Done(rest, esc) => {
-                                let &(k, _) = cs.peek().unwrap();
-                                // digits are always single byte ASCII characters
-                                let consumed = input[k..].len() - rest.len();
-                                for _ in 0..consumed {
-                                    let _ = cs.next();
-                                }
-                                s.push(esc);
-                            }
-                            Incomplete(s) => return Incomplete(s),
-                            Error(e) => return Error(e),
-                        }
-                    }
-                }
-                _ => {
-                    return Error(error_position!(
-                        ErrorKind::Custom(5 /* FIXME */),
-                        input
-                    ));
-                }
-            },
-            _ => s.push(c),
-        }
-    }
-    Error(error_position!(ErrorKind::Custom(3 /* FIXME */), input))
-}
-
-named!(string_lit<&str, String>, delimited!(tag!("\""), string_lit_inner, tag!("\"")));
-
-named!(keyword<&str, Keyword>, alt!(
-    value!(Keyword::Let, ident_tag!("let")) |
-    value!(Keyword::In, ident_tag!("in")) |
-    value!(Keyword::If, ident_tag!("if")) |
-    value!(Keyword::Then, ident_tag!("then")) |
-    value!(Keyword::Else, ident_tag!("else"))
-));
-
-named!(type_const<&str, Const>, alt!(
-    value!(Const::Type, ident_tag!("Type")) |
-    value!(Const::Kind, ident_tag!("Kind"))
-));
-
-named!(list_like<&str, ListLike>, alt!(
-    value!(ListLike::List, ident_tag!("List")) |
-    value!(ListLike::Optional, ident_tag!("Optional"))
-));
-
-named!(builtin<&str, Builtin>, alt!(
-    value!(NaturalFold, ident_tag!("Natural/fold")) |
-    value!(NaturalBuild, ident_tag!("Natural/build")) |
-    value!(NaturalIsZero, ident_tag!("Natural/isZero")) |
-    value!(NaturalEven, ident_tag!("Natural/even")) |
-    value!(NaturalOdd, ident_tag!("Natural/odd")) |
-    value!(NaturalShow, ident_tag!("Natural/show")) |
-    value!(Natural, ident_tag!("Natural")) |
-    value!(Integer, ident_tag!("Integer")) |
-    value!(Double, ident_tag!("Double")) |
-    value!(Text, ident_tag!("Text")) |
-    value!(ListBuild, ident_tag!("List/build")) |
-    value!(ListFold, ident_tag!("List/fold")) |
-    value!(ListLength, ident_tag!("List/length")) |
-    value!(ListHead, ident_tag!("List/head")) |
-    value!(ListLast, ident_tag!("List/last")) |
-    value!(ListIndexed, ident_tag!("List/indexed")) |
-    value!(ListReverse, ident_tag!("List/reverse")) |
-    value!(OptionalFold, ident_tag!("Optional/fold")) |
-    value!(Bool, ident_tag!("Bool"))
-));
-
-named!(token<&str, Tok>, alt!(
-    value!(Tok::Pi, ident_tag!("forall")) |
-    value!(Tok::Pi, tag!("∀")) |
-    value!(Tok::Lambda, tag!("\\")) |
-    value!(Tok::Lambda, tag!("λ")) |
-    value!(Tok::Combine, tag!("/\\")) |
-    value!(Tok::Combine, tag!("∧")) |
-    value!(Tok::Arrow, tag!("->")) |
-    value!(Tok::Arrow, tag!("→")) |
-
-    map!(type_const, Tok::Const) |
-    map!(boolean, Tok::Bool) |
-    map!(keyword, Tok::Keyword) |
-    map!(builtin, Tok::Builtin) |
-    map!(list_like, Tok::ListLike) |
-    map!(natural, Tok::Natural) |
-    map!(integer, Tok::Integer) |
-    map!(identifier, Tok::Identifier) |
-    map!(string_lit, Tok::Text) |
-
-    value!(Tok::BraceL, tag!("{")) |
-    value!(Tok::BraceR, tag!("}")) |
-    value!(Tok::BracketL, tag!("[")) |
-    value!(Tok::BracketR, tag!("]")) |
-    value!(Tok::ParenL, tag!("(")) |
-    value!(Tok::ParenR, tag!(")")) |
-    value!(Tok::BoolAnd, tag!("&&")) |
-    value!(Tok::BoolOr, tag!("||")) |
-    value!(Tok::CompareEQ, tag!("==")) |
-    value!(Tok::CompareNE, tag!("!=")) |
-    value!(Tok::Append, tag!("++")) |
-    value!(Tok::Times, tag!("*")) |
-    value!(Tok::Plus, tag!("+")) |
-    value!(Tok::Comma, tag!(",")) |
-    value!(Tok::Dot, tag!(".")) |
-    value!(Tok::Ascription, tag!(":")) |
-    value!(Tok::Equals, tag!("="))
-));
-
-fn find_end(input: &str, ending: &str) -> Option<usize> {
-    input.find(ending).map(|i| i + ending.len())
-}
-
-pub struct Lexer<'input> {
-    input: &'input str,
-    offset: usize,
-}
-
-impl<'input> Lexer<'input> {
-    pub fn new(input: &'input str) -> Self {
-        Lexer {
-            input: input,
-            offset: 0,
-        }
-    }
-
-    fn current_input(&mut self) -> &'input str {
-        &self.input[self.offset..]
-    }
-
-    fn skip_whitespace(&mut self) -> bool {
-        let input = self.current_input();
-        let trimmed = input.trim_start();
-        let whitespace_len = input.len() - trimmed.len();
-        let skipped = whitespace_len > 0;
-        if skipped {
-            // println!("skipped {} whitespace bytes in {}..{}", whitespace_len, self.offset, self.offset + whitespace_len);
-            self.offset += whitespace_len;
-        }
-        skipped
-    }
-
-    fn skip_comments(&mut self) -> bool {
-        let input = self.current_input();
-        if !input.is_char_boundary(0) || !input.is_char_boundary(2) {
-            return false;
-        }
-        let skip = match &input[0..2] {
-            "{-" => find_end(input, "-}"),
-            "--" => find_end(input, "\n"), // Also skips past \r\n (CRLF)
-            _ => None,
-        }
-        .unwrap_or(0);
-        // println!("skipped {} bytes of comment", skip);
-        self.offset += skip;
-        skip != 0
-    }
-
-    fn skip_comments_and_whitespace(&mut self) {
-        while self.skip_whitespace() || self.skip_comments() {}
-    }
-}
-
-impl<'input> Iterator for Lexer<'input> {
-    type Item = Spanned<Tok<'input>, usize, LexicalError>;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        use nom::IResult::*;
-        self.skip_comments_and_whitespace();
-        let input = self.current_input();
-        if input.is_empty() {
-            return None;
-        }
-        match token(input) {
-            Done(rest, t) => {
-                let parsed_len = input.len() - rest.len();
-                //println!("parsed {} bytes => {:?}", parsed_len, t);
-                let start = self.offset;
-                self.offset += parsed_len;
-                Some(Ok((start, t, self.offset)))
-            }
-            Error(e) => {
-                let offset = self.offset;
-                self.offset = self.input.len();
-                Some(Err(LexicalError::Error(offset, e)))
-            }
-            Incomplete(needed) => Some(Err(LexicalError::Incomplete(needed))),
-        }
-    }
-}
-
-#[test]
-fn test_lex() {
-    use self::Tok::*;
-    let s = "λ(b : Bool) → b == False";
-    let expected = [
-        Lambda,
-        ParenL,
-        Identifier("b"),
-        Ascription,
-        Builtin(crate::core::Builtin::Bool),
-        ParenR,
-        Arrow,
-        Identifier("b"),
-        CompareEQ,
-        Bool(false),
-    ];
-    let lexer = Lexer::new(s);
-    let tokens = lexer.map(|r| r.unwrap().1).collect::<Vec<_>>();
-    assert_eq!(&tokens, &expected);
-
-    assert_eq!(string_lit(r#""a\&b""#).to_result(), Ok("ab".to_owned()));
-    assert_eq!(
-        string_lit(r#""a\     \b""#).to_result(),
-        Ok("ab".to_owned())
-    );
-    assert!(string_lit(r#""a\     b""#).is_err());
-    assert_eq!(string_lit(r#""a\nb""#).to_result(), Ok("a\nb".to_owned()));
-    assert_eq!(
-        string_lit(r#""\o141\x62\99""#).to_result(),
-        Ok("abc".to_owned())
-    );
-}
diff --git a/dhall/src/lib.rs b/dhall/src/lib.rs
index 7cc96e1..902df53 100644
--- a/dhall/src/lib.rs
+++ b/dhall/src/lib.rs
@@ -2,11 +2,4 @@
 #![feature(trace_macros)]
 
 pub mod context;
-mod core;
-pub use crate::core::*;
-use lalrpop_util::lalrpop_mod;
-lalrpop_mod!(pub grammar);
-mod grammar_util;
-pub mod lexer;
-pub mod parser;
 pub mod typecheck;
diff --git a/dhall/src/main.rs b/dhall/src/main.rs
index 78a2905..3e8aca4 100644
--- a/dhall/src/main.rs
+++ b/dhall/src/main.rs
@@ -3,6 +3,7 @@ use std::io::{self, Read};
 use term_painter::ToStyle;
 
 use dhall::*;
+use dhall_core::*;
 
 const ERROR_STYLE: term_painter::Color = term_painter::Color::Red;
 const BOLD: term_painter::Attr = term_painter::Attr::Bold;
diff --git a/dhall/src/parser.rs b/dhall/src/parser.rs
deleted file mode 100644
index 6b20c01..0000000
--- a/dhall/src/parser.rs
+++ /dev/null
@@ -1,827 +0,0 @@
-use std::collections::BTreeMap;
-// use itertools::*;
-use lalrpop_util;
-use pest::iterators::Pair;
-use pest::Parser;
-
-use dhall_parser::{DhallParser, Rule};
-
-use crate::core;
-use crate::core::{bx, BinOp, Builtin, Const, Expr, V};
-use crate::grammar;
-use crate::grammar_util::{BoxExpr, ParsedExpr};
-use crate::lexer::{Lexer, LexicalError, Tok};
-
-pub fn parse_expr_lalrpop(
-    s: &str,
-) -> Result<BoxExpr, lalrpop_util::ParseError<usize, Tok, LexicalError>> {
-    grammar::ExprParser::new().parse(Lexer::new(s))
-    // Ok(bx(Expr::BoolLit(false)))
-}
-
-pub type ParseError = pest::error::Error<Rule>;
-
-pub type ParseResult<T> = Result<T, ParseError>;
-
-pub fn custom_parse_error(pair: &Pair<Rule>, msg: String) -> ParseError {
-    let msg =
-        format!("{} while matching on:\n{}", msg, debug_pair(pair.clone()));
-    let e = pest::error::ErrorVariant::CustomError { message: msg };
-    pest::error::Error::new_from_span(e, pair.as_span())
-}
-
-fn debug_pair(pair: Pair<Rule>) -> String {
-    use std::fmt::Write;
-    let mut s = String::new();
-    fn aux(s: &mut String, indent: usize, prefix: String, pair: Pair<Rule>) {
-        let indent_str = "| ".repeat(indent);
-        let rule = pair.as_rule();
-        let contents = pair.as_str().clone();
-        let mut inner = pair.into_inner();
-        let mut first = true;
-        while let Some(p) = inner.next() {
-            if first {
-                first = false;
-                let last = inner.peek().is_none();
-                if last && p.as_str() == contents {
-                    let prefix = format!("{}{:?} > ", prefix, rule);
-                    aux(s, indent, prefix, p);
-                    continue;
-                } else {
-                    writeln!(
-                        s,
-                        r#"{}{}{:?}: "{}""#,
-                        indent_str, prefix, rule, contents
-                    )
-                    .unwrap();
-                }
-            }
-            aux(s, indent + 1, "".into(), p);
-        }
-        if first {
-            writeln!(
-                s,
-                r#"{}{}{:?}: "{}""#,
-                indent_str, prefix, rule, contents
-            )
-            .unwrap();
-        }
-    }
-    aux(&mut s, 0, "".into(), pair);
-    s
-}
-
-/* Macro to pattern-match iterators.
- * Returns `Result<_, IterMatchError<_>>`.
- *
- * Example:
- * ```
- * let vec = vec![1, 2, 3];
- *
- * match_iter!(vec.into_iter(); (x, y?, z) => {
- *  // x: T
- *  // y: Option<T>
- *  // z: T
- * })
- *
- * // or
- * match_iter!(vec.into_iter(); (x, y, z*) => {
- *  // x, y: T
- *  // z: impl Iterator<T>
- * })
- * ```
- *
-*/
-#[derive(Debug)]
-enum IterMatchError<T> {
-    NotEnoughItems,
-    TooManyItems,
-    NoMatchFound,
-    Other(T), // Allow other macros to inject their own errors
-}
-macro_rules! match_iter {
-    // Everything else pattern
-    (@match 0, $iter:expr, $x:ident* $($rest:tt)*) => {
-        match_iter!(@match 2, $iter $($rest)*);
-        #[allow(unused_mut)]
-        let mut $x = $iter;
-    };
-    // Alias to use in macros
-    (@match 0, $iter:expr, $x:ident?? $($rest:tt)*) => {
-        match_iter!(@match 2, $iter $($rest)*);
-        #[allow(unused_mut)]
-        let mut $x = $iter;
-    };
-    // Optional pattern
-    (@match 0, $iter:expr, $x:ident? $($rest:tt)*) => {
-        match_iter!(@match 1, $iter $($rest)*);
-        #[allow(unused_mut)]
-        let mut $x = $iter.next();
-        match $iter.next() {
-            Some(_) => break Err(IterMatchError::TooManyItems),
-            None => {},
-        };
-    };
-    // Normal pattern
-    (@match 0, $iter:expr, $x:ident $($rest:tt)*) => {
-        #[allow(unused_mut)]
-        let mut $x = match $iter.next() {
-            Some(x) => x,
-            None => break Err(IterMatchError::NotEnoughItems),
-        };
-        match_iter!(@match 0, $iter $($rest)*);
-    };
-    // Normal pattern after a variable length one: declare reversed and take from the end
-    (@match $w:expr, $iter:expr, $x:ident $($rest:tt)*) => {
-        match_iter!(@match $w, $iter $($rest)*);
-        #[allow(unused_mut)]
-        let mut $x = match $iter.next_back() {
-            Some(x) => x,
-            None => break Err(IterMatchError::NotEnoughItems),
-        };
-    };
-
-    // Check no elements remain
-    (@match 0, $iter:expr $(,)*) => {
-        match $iter.next() {
-            Some(_) => break Err(IterMatchError::TooManyItems),
-            None => {},
-        };
-    };
-    (@match $_:expr, $iter:expr) => {};
-
-    (@panic; $($args:tt)*) => {
-        {
-            let ret: Result<_, IterMatchError<()>> = match_iter!($($args)*);
-            ret.unwrap()
-        }
-    };
-    ($iter:expr; ($($args:tt)*) => $body:expr) => {
-        {
-            #[allow(unused_mut)]
-            let mut iter = $iter;
-            // Not a real loop; used for error handling
-            let ret: Result<_, IterMatchError<_>> = loop {
-                match_iter!(@match 0, iter, $($args)*);
-                break Ok($body);
-            };
-            ret
-        }
-    };
-}
-
-/* Extends match_iter with typed matches. Takes a callback that determines
- * when a capture matches.
- * Returns `Result<_, IterMatchError<_>>`; errors returned by the callback will
- * get propagated using IterMatchError::Other.
- *
- * Example:
- * ```
- * macro_rules! callback {
- *     (@type_callback, positive, $x:expr) => {
- *         if $x >= 0 { Ok($x) } else { Err(()) }
- *     };
- *     (@type_callback, negative, $x:expr) => {
- *         if $x <= 0 { Ok($x) } else { Err(()) }
- *     };
- *     (@type_callback, any, $x:expr) => {
- *         Ok($x)
- *     };
- * }
- *
- * let vec = vec![-1, 2, 3];
- *
- * match_iter_typed!(callback; vec.into_iter();
- *     (x: positive, y?: negative, z: any) => { ... },
- * )
- * ```
- *
-*/
-macro_rules! match_iter_typed {
-    // Collect untyped arguments to pass to match_iter!
-    (@collect, ($($vars:tt)*), ($($args:tt)*), ($($acc:tt)*), ($x:ident : $ty:ident, $($rest:tt)*)) => {
-        match_iter_typed!(@collect, ($($vars)*), ($($args)*), ($($acc)*, $x), ($($rest)*))
-    };
-    (@collect, ($($vars:tt)*), ($($args:tt)*), ($($acc:tt)*), ($x:ident? : $ty:ident, $($rest:tt)*)) => {
-        match_iter_typed!(@collect, ($($vars)*), ($($args)*), ($($acc)*, $x?), ($($rest)*))
-    };
-    (@collect, ($($vars:tt)*), ($($args:tt)*), ($($acc:tt)*), ($x:ident* : $ty:ident, $($rest:tt)*)) => {
-        match_iter_typed!(@collect, ($($vars)*), ($($args)*), ($($acc)*, $x??), ($($rest)*))
-    };
-    // Catch extra comma if exists
-    (@collect, ($($vars:tt)*), ($($args:tt)*), (,$($acc:tt)*), ($(,)*)) => {
-        match_iter_typed!(@collect, ($($vars)*), ($($args)*), ($($acc)*), ())
-    };
-    (@collect, ($iter:expr, $body:expr, $callback:ident, $error:ident), ($($args:tt)*), ($($acc:tt)*), ($(,)*)) => {
-        match_iter!($iter; ($($acc)*) => {
-            match_iter_typed!(@callback, $callback, $iter, $($args)*);
-            $body
-        })
-    };
-
-    // Pass the matches through the callback
-    (@callback, $callback:ident, $iter:expr, $x:ident : $ty:ident $($rest:tt)*) => {
-        let $x = $callback!(@type_callback, $ty, $x);
-        #[allow(unused_mut)]
-        let mut $x = match $x {
-            Ok(x) => x,
-            Err(e) => break Err(IterMatchError::Other(e)),
-        };
-        match_iter_typed!(@callback, $callback, $iter $($rest)*);
-    };
-    (@callback, $callback: ident, $iter:expr, $x:ident? : $ty:ident $($rest:tt)*) => {
-        let $x = $x.map(|x| $callback!(@type_callback, $ty, x));
-        #[allow(unused_mut)]
-        let mut $x = match $x {
-            Some(Ok(x)) => Some(x),
-            Some(Err(e)) => break Err(IterMatchError::Other(e)),
-            None => None,
-        };
-        match_iter_typed!(@callback, $callback, $iter $($rest)*);
-    };
-    (@callback, $callback: ident, $iter:expr, $x:ident* : $ty:ident $($rest:tt)*) => {
-        let $x = $x.map(|x| $callback!(@type_callback, $ty, x)).collect();
-        let $x: Vec<_> = match $x {
-            Ok(x) => x,
-            Err(e) => break Err(IterMatchError::Other(e)),
-        };
-        #[allow(unused_mut)]
-        let mut $x = $x.into_iter();
-        match_iter_typed!(@callback, $callback, $iter $($rest)*);
-    };
-    (@callback, $callback:ident, $iter:expr $(,)*) => {};
-
-    ($callback:ident; $iter:expr; ($($args:tt)*) => $body:expr) => {
-        {
-            #[allow(unused_mut)]
-            let mut iter = $iter;
-            match_iter_typed!(@collect,
-                (iter, $body, $callback, last_error),
-                ($($args)*), (), ($($args)*,)
-            )
-        }
-    };
-}
-
-/* Extends match_iter and match_iter_typed with branching.
- * Returns `Result<_, IterMatchError<_>>`; errors returned by the callback will
- * get propagated using IterMatchError::Other.
- * Allows multiple branches. The passed iterator must be Clone.
- * Will check the branches in order, testing each branch using the callback macro provided.
- *
- * Example:
- * ```
- * macro_rules! callback {
- *     (@type_callback, positive, $x:expr) => {
- *         if $x >= 0 { Ok($x) } else { Err(()) }
- *     };
- *     (@type_callback, negative, $x:expr) => {
- *         if $x <= 0 { Ok($x) } else { Err(()) }
- *     };
- *     (@type_callback, any, $x:expr) => {
- *         Ok($x)
- *     };
- *     (@branch_callback, typed, $($args:tt)*) => {
- *         match_iter_typed!(callback; $($args)*)
- *     };
- *     (@branch_callback, untyped, $($args:tt)*) => {
- *         match_iter!($($args)*)
- *     };
- * }
- *
- * let vec = vec![-1, 2, 3];
- *
- * match_iter_branching!(branch_callback; vec.into_iter();
- *     typed!(x: positive, y?: negative, z: any) => { ... },
- *     untyped!(x, y, z) => { ... },
- * )
- * ```
- *
-*/
-macro_rules! match_iter_branching {
-    (@noclone, $callback:ident; $arg:expr; $( $submac:ident!($($args:tt)*) => $body:expr ),* $(,)*) => {
-        {
-            #[allow(unused_assignments)]
-            let mut last_error = IterMatchError::NoMatchFound;
-            // Not a real loop; used for error handling
-            // Would use loop labels but they create warnings
-            #[allow(unreachable_code)]
-            loop {
-                $(
-                    let matched: Result<_, IterMatchError<_>> =
-                        $callback!(@branch_callback, $submac, $arg; ($($args)*) => $body);
-                    #[allow(unused_assignments)]
-                    match matched {
-                        Ok(v) => break Ok(v),
-                        Err(e) => last_error = e,
-                    };
-                )*
-                break Err(last_error);
-            }
-        }
-    };
-    ($callback:ident; $iter:expr; $($args:tt)*) => {
-        {
-            #[allow(unused_mut)]
-            let mut iter = $iter;
-            match_iter_branching!(@noclone, $callback; iter.clone(); $($args)*)
-        }
-    };
-}
-
-macro_rules! match_pair {
-    (@type_callback, $ty:ident, $x:expr) => {
-        $ty($x)
-    };
-    (@branch_callback, children, $pair:expr; $($args:tt)*) => {
-        {
-            #[allow(unused_mut)]
-            let mut pairs = $pair.clone().into_inner();
-            match_iter_typed!(match_pair; pairs; $($args)*)
-        }
-    };
-    (@branch_callback, self, $pair:expr; ($x:ident : $ty:ident) => $body:expr) => {
-        {
-            let $x = match_pair!(@type_callback, $ty, $pair.clone());
-            match $x {
-                Ok($x) => Ok($body),
-                Err(e) => Err(IterMatchError::Other(e)),
-            }
-        }
-    };
-    (@branch_callback, raw_pair, $pair:expr; ($x:ident) => $body:expr) => {
-        {
-            let $x = $pair.clone();
-            Ok($body)
-        }
-    };
-    (@branch_callback, captured_str, $pair:expr; ($x:ident) => $body:expr) => {
-        {
-            let $x = $pair.as_str();
-            Ok($body)
-        }
-    };
-
-    ($pair:expr; $($args:tt)*) => {
-        {
-            let pair = $pair;
-            let result = match_iter_branching!(@noclone, match_pair; pair; $($args)*);
-            result.map_err(|e| match e {
-                IterMatchError::Other(e) => e,
-                _ => custom_parse_error(&pair, "No match found".to_owned()),
-            })
-        }
-    };
-}
-
-macro_rules! make_pest_parse_function {
-    ($name:ident<$o:ty>; $submac:ident!( $($args:tt)* )) => (
-        #[allow(unused_variables)]
-        #[allow(non_snake_case)]
-        fn $name<'a>(pair: Pair<'a, Rule>) -> ParseResult<$o> {
-            $submac!(pair; $($args)*)
-        }
-    );
-}
-
-macro_rules! named {
-    ($name:ident<$o:ty>; $($args:tt)*) => (
-        make_pest_parse_function!($name<$o>; match_pair!( $($args)* ));
-    );
-}
-
-macro_rules! rule {
-    ($name:ident<$o:ty>; $($args:tt)*) => (
-        make_pest_parse_function!($name<$o>; match_rule!(
-            Rule::$name => match_pair!( $($args)* ),
-        ));
-    );
-}
-
-macro_rules! rule_group {
-    ($name:ident<$o:ty>; $($ty:ident),*) => (
-        make_pest_parse_function!($name<$o>; match_rule!(
-            $(
-                Rule::$ty => match_pair!(raw_pair!(p) => $ty(p)?),
-            )*
-        ));
-    );
-}
-
-macro_rules! match_rule {
-    ($pair:expr; $($pat:pat => $submac:ident!( $($args:tt)* ),)*) => {
-        {
-            #[allow(unreachable_patterns)]
-            match $pair.as_rule() {
-                $(
-                    $pat => $submac!($pair; $($args)*),
-                )*
-                r => Err(custom_parse_error(&$pair, format!("Unexpected {:?}", r))),
-            }
-        }
-    };
-}
-
-rule!(EOI<()>; children!() => ());
-
-named!(str<&'a str>; captured_str!(s) => s.trim());
-
-named!(raw_str<&'a str>; captured_str!(s) => s);
-
-rule!(escaped_quote_pair<&'a str>;
-    children!() => "''"
-);
-rule!(escaped_interpolation<&'a str>;
-    children!() => "${"
-);
-
-rule!(single_quote_continue<Vec<&'a str>>;
-    // TODO: handle interpolation
-    // children!(c: expression, rest: single_quote_continue) => {
-    //     rest.push(c); rest
-    // },
-    children!(c: escaped_quote_pair, rest: single_quote_continue) => {
-        rest.push(c); rest
-    },
-    children!(c: escaped_interpolation, rest: single_quote_continue) => {
-        rest.push(c); rest
-    },
-    // capture interpolation as string
-    children!(c: raw_str, rest: single_quote_continue) => {
-        rest.push(c); rest
-    },
-    children!() => {
-        vec![]
-    },
-);
-
-rule!(let_binding<(&'a str, Option<BoxExpr<'a>>, BoxExpr<'a>)>;
-    children!(name: str, annot?: expression, expr: expression) => (name, annot, expr)
-);
-
-named!(record_entry<(&'a str, BoxExpr<'a>)>;
-    children!(name: str, expr: expression) => (name, expr)
-);
-
-named!(partial_record_entries<(BoxExpr<'a>, BTreeMap<&'a str, ParsedExpr<'a>>)>;
-    children!(expr: expression, entries*: record_entry) => {
-        let mut map: BTreeMap<&str, ParsedExpr> = BTreeMap::new();
-        for (n, e) in entries {
-            map.insert(n, *e);
-        }
-        (expr, map)
-    }
-);
-
-rule!(non_empty_record_literal<(BoxExpr<'a>, BTreeMap<&'a str, ParsedExpr<'a>>)>;
-    self!(x: partial_record_entries) => x
-);
-
-rule!(non_empty_record_type<(BoxExpr<'a>, BTreeMap<&'a str, ParsedExpr<'a>>)>;
-    self!(x: partial_record_entries) => x
-);
-
-rule!(union_type_entry<(&'a str, BoxExpr<'a>)>;
-    children!(name: str, expr: expression) => (name, expr)
-);
-
-rule!(union_type_entries<BTreeMap<&'a str, ParsedExpr<'a>>>;
-    children!(entries*: union_type_entry) => {
-        let mut map: BTreeMap<&str, ParsedExpr> = BTreeMap::new();
-        for (n, e) in entries {
-            map.insert(n, *e);
-        }
-        map
-    }
-);
-
-rule!(non_empty_union_type_or_literal
-      <(Option<(&'a str, BoxExpr<'a>)>, BTreeMap<&'a str, ParsedExpr<'a>>)>;
-    children!(label: str, e: expression, entries: union_type_entries) => {
-        (Some((label, e)), entries)
-    },
-    children!(l: str, e: expression, rest: non_empty_union_type_or_literal) => {
-        let (x, mut entries) = rest;
-        entries.insert(l, *e);
-        (x, entries)
-    },
-    children!(l: str, e: expression) => {
-        let mut entries = BTreeMap::new();
-        entries.insert(l, *e);
-        (None, entries)
-    },
-);
-
-rule!(empty_union_type<()>; children!() => ());
-
-rule_group!(expression<BoxExpr<'a>>;
-    identifier_raw,
-    lambda_expression,
-    ifthenelse_expression,
-    let_expression,
-    forall_expression,
-    arrow_expression,
-    merge_expression,
-    empty_collection,
-    non_empty_optional,
-
-    annotated_expression,
-    import_alt_expression,
-    or_expression,
-    plus_expression,
-    text_append_expression,
-    list_append_expression,
-    and_expression,
-    combine_expression,
-    prefer_expression,
-    combine_types_expression,
-    times_expression,
-    equal_expression,
-    not_equal_expression,
-    application_expression,
-
-    selector_expression_raw,
-    literal_expression_raw,
-    empty_record_type,
-    empty_record_literal,
-    non_empty_record_type_or_literal,
-    union_type_or_literal,
-    non_empty_list_literal_raw,
-    final_expression
-);
-
-// TODO: parse escapes and interpolation
-rule!(double_quote_literal<String>;
-    children!(strs*: raw_str) => {
-        strs.collect()
-    }
-);
-rule!(single_quote_literal<String>;
-    children!(eol: raw_str, contents: single_quote_continue) => {
-        contents.push(eol);
-        contents.into_iter().rev().collect()
-    }
-);
-
-rule!(double_literal_raw<core::Double>;
-    raw_pair!(pair) => {
-        pair.as_str().trim()
-            .parse()
-            .map_err(|e: std::num::ParseFloatError| custom_parse_error(&pair, format!("{}", e)))?
-    }
-);
-
-rule!(minus_infinity_literal<()>; children!() => ());
-rule!(plus_infinity_literal<()>; children!() => ());
-rule!(NaN_raw<()>; children!() => ());
-
-rule!(natural_literal_raw<core::Natural>;
-    raw_pair!(pair) => {
-        pair.as_str().trim()
-            .parse()
-            .map_err(|e: std::num::ParseIntError| custom_parse_error(&pair, format!("{}", e)))?
-    }
-);
-
-rule!(integer_literal_raw<core::Integer>;
-    raw_pair!(pair) => {
-        pair.as_str().trim()
-            .parse()
-            .map_err(|e: std::num::ParseIntError| custom_parse_error(&pair, format!("{}", e)))?
-    }
-);
-
-rule!(identifier_raw<BoxExpr<'a>>;
-    children!(name: str, idx?: natural_literal_raw) => {
-        match Builtin::parse(name) {
-            Some(b) => bx(Expr::Builtin(b)),
-            None => match name {
-                "True" => bx(Expr::BoolLit(true)),
-                "False" => bx(Expr::BoolLit(false)),
-                "Type" => bx(Expr::Const(Const::Type)),
-                "Kind" => bx(Expr::Const(Const::Kind)),
-                name => bx(Expr::Var(V(name, idx.unwrap_or(0)))),
-            }
-        }
-    }
-);
-
-rule!(lambda_expression<BoxExpr<'a>>;
-    children!(label: str, typ: expression, body: expression) => {
-        bx(Expr::Lam(label, typ, body))
-    }
-);
-
-rule!(ifthenelse_expression<BoxExpr<'a>>;
-    children!(cond: expression, left: expression, right: expression) => {
-        bx(Expr::BoolIf(cond, left, right))
-    }
-);
-
-rule!(let_expression<BoxExpr<'a>>;
-    children!(bindings*: let_binding, final_expr: expression) => {
-        bindings.fold(final_expr, |acc, x| bx(Expr::Let(x.0, x.1, x.2, acc)))
-    }
-);
-
-rule!(forall_expression<BoxExpr<'a>>;
-    children!(label: str, typ: expression, body: expression) => {
-        bx(Expr::Pi(label, typ, body))
-    }
-);
-
-rule!(arrow_expression<BoxExpr<'a>>;
-    children!(typ: expression, body: expression) => {
-        bx(Expr::Pi("_", typ, body))
-    }
-);
-
-rule!(merge_expression<BoxExpr<'a>>;
-    children!(x: expression, y: expression, z?: expression) => {
-        bx(Expr::Merge(x, y, z))
-    }
-);
-
-rule!(empty_collection<BoxExpr<'a>>;
-    children!(x: str, y: expression) => {
-       match x {
-          "Optional" => bx(Expr::OptionalLit(Some(y), vec![])),
-          "List" => bx(Expr::ListLit(Some(y), vec![])),
-          _ => unreachable!(),
-       }
-    }
-);
-
-rule!(non_empty_optional<BoxExpr<'a>>;
-    children!(x: expression, _y: str, z: expression) => {
-        bx(Expr::OptionalLit(Some(z), vec![*x]))
-    }
-);
-
-macro_rules! binop {
-    ($rule:ident, $op:ident) => {
-        rule!($rule<BoxExpr<'a>>;
-            children!(first: expression, rest*: expression) => {
-                rest.fold(first, |acc, e| bx(Expr::BinOp(BinOp::$op, acc, e)))
-            }
-        );
-    };
-}
-
-rule!(annotated_expression<BoxExpr<'a>>;
-    children!(e: expression, annot: expression) => {
-        bx(Expr::Annot(e, annot))
-    },
-    children!(e: expression) => e,
-);
-
-binop!(import_alt_expression, ImportAlt);
-binop!(or_expression, BoolOr);
-binop!(plus_expression, NaturalPlus);
-binop!(text_append_expression, TextAppend);
-binop!(list_append_expression, ListAppend);
-binop!(and_expression, BoolAnd);
-binop!(combine_expression, Combine);
-binop!(prefer_expression, Prefer);
-binop!(combine_types_expression, CombineTypes);
-binop!(times_expression, NaturalTimes);
-binop!(equal_expression, BoolEQ);
-binop!(not_equal_expression, BoolNE);
-
-rule!(application_expression<BoxExpr<'a>>;
-    children!(first: expression, rest*: expression) => {
-        rest.fold(first, |acc, e| bx(Expr::App(acc, e)))
-    }
-);
-
-rule!(selector_expression_raw<BoxExpr<'a>>;
-    children!(first: expression, rest*: str) => {
-        rest.fold(first, |acc, e| bx(Expr::Field(acc, e)))
-    }
-);
-
-rule!(literal_expression_raw<BoxExpr<'a>>;
-    children!(n: double_literal_raw) => bx(Expr::DoubleLit(n)),
-    children!(n: minus_infinity_literal) => bx(Expr::DoubleLit(std::f64::NEG_INFINITY)),
-    children!(n: plus_infinity_literal) => bx(Expr::DoubleLit(std::f64::INFINITY)),
-    children!(n: NaN_raw) => bx(Expr::DoubleLit(std::f64::NAN)),
-    children!(n: natural_literal_raw) => bx(Expr::NaturalLit(n)),
-    children!(n: integer_literal_raw) => bx(Expr::IntegerLit(n)),
-    children!(s: double_quote_literal) => bx(Expr::TextLit(s)),
-    children!(s: single_quote_literal) => bx(Expr::TextLit(s)),
-    children!(e: expression) => e,
-);
-
-rule!(empty_record_type<BoxExpr<'a>>;
-    children!() => bx(Expr::Record(BTreeMap::new()))
-);
-rule!(empty_record_literal<BoxExpr<'a>>;
-    children!() => bx(Expr::RecordLit(BTreeMap::new()))
-);
-rule!(non_empty_record_type_or_literal<BoxExpr<'a>>;
-    children!(first_label: str, rest: non_empty_record_type) => {
-        let (first_expr, mut map) = rest;
-        map.insert(first_label, *first_expr);
-        bx(Expr::Record(map))
-    },
-    children!(first_label: str, rest: non_empty_record_literal) => {
-        let (first_expr, mut map) = rest;
-        map.insert(first_label, *first_expr);
-        bx(Expr::RecordLit(map))
-    },
-);
-
-rule!(union_type_or_literal<BoxExpr<'a>>;
-    children!(_e: empty_union_type) => {
-        bx(Expr::Union(BTreeMap::new()))
-    },
-    children!(x: non_empty_union_type_or_literal) => {
-        match x {
-            (Some((l, e)), entries) => bx(Expr::UnionLit(l, e, entries)),
-            (None, entries) => bx(Expr::Union(entries)),
-        }
-    },
-);
-
-rule!(non_empty_list_literal_raw<BoxExpr<'a>>;
-    children!(items*: expression) => {
-        bx(Expr::ListLit(None, items.map(|x| *x).collect()))
-    }
-);
-
-rule!(final_expression<BoxExpr<'a>>;
-    children!(e: expression, _eoi: EOI) => e
-);
-
-pub fn parse_expr_pest(s: &str) -> ParseResult<BoxExpr> {
-    let pairs = DhallParser::parse(Rule::final_expression, s)?;
-    // Match the only item in the pairs iterator
-    match_iter!(@panic; pairs; (p) => expression(p))
-    // Ok(bx(Expr::BoolLit(false)))
-}
-
-#[test]
-fn test_parse() {
-    use crate::core::BinOp::*;
-    use crate::core::Expr::*;
-    // let expr = r#"{ x = "foo", y = 4 }.x"#;
-    // let expr = r#"(1 + 2) * 3"#;
-    let expr = r#"if True then 1 + 3 * 5 else 2"#;
-    println!("{:?}", parse_expr_lalrpop(expr));
-    use std::thread;
-    // I don't understand why it stack overflows even on tiny expressions...
-    thread::Builder::new()
-        .stack_size(3 * 1024 * 1024)
-        .spawn(move || match parse_expr_pest(expr) {
-            Err(e) => {
-                println!("{:?}", e);
-                println!("{}", e);
-            }
-            ok => println!("{:?}", ok),
-        })
-        .unwrap()
-        .join()
-        .unwrap();
-    // assert_eq!(parse_expr_pest(expr).unwrap(), parse_expr_lalrpop(expr).unwrap());
-    // assert!(false);
-
-    println!("test {:?}", parse_expr_lalrpop("3 + 5 * 10"));
-    assert!(parse_expr_lalrpop("22").is_ok());
-    assert!(parse_expr_lalrpop("(22)").is_ok());
-    assert_eq!(
-        parse_expr_lalrpop("3 + 5 * 10").ok(),
-        Some(Box::new(BinOp(
-            NaturalPlus,
-            Box::new(NaturalLit(3)),
-            Box::new(BinOp(
-                NaturalTimes,
-                Box::new(NaturalLit(5)),
-                Box::new(NaturalLit(10))
-            ))
-        )))
-    );
-    // The original parser is apparently right-associative
-    assert_eq!(
-        parse_expr_lalrpop("2 * 3 * 4").ok(),
-        Some(Box::new(BinOp(
-            NaturalTimes,
-            Box::new(NaturalLit(2)),
-            Box::new(BinOp(
-                NaturalTimes,
-                Box::new(NaturalLit(3)),
-                Box::new(NaturalLit(4))
-            ))
-        )))
-    );
-    assert!(parse_expr_lalrpop("((((22))))").is_ok());
-    assert!(parse_expr_lalrpop("((22)").is_err());
-    println!("{:?}", parse_expr_lalrpop("\\(b : Bool) -> b == False"));
-    assert!(parse_expr_lalrpop("\\(b : Bool) -> b == False").is_ok());
-    println!("{:?}", parse_expr_lalrpop("foo.bar"));
-    assert!(parse_expr_lalrpop("foo.bar").is_ok());
-    assert!(parse_expr_lalrpop("[] : List Bool").is_ok());
-
-    // println!("{:?}", parse_expr_lalrpop("< Left = True | Right : Natural >"));
-    // println!("{:?}", parse_expr_lalrpop(r#""bl${42}ah""#));
-    // assert!(parse_expr_lalrpop("< Left = True | Right : Natural >").is_ok());
-}
diff --git a/dhall/src/typecheck.rs b/dhall/src/typecheck.rs
index 976293d..61a83e7 100644
--- a/dhall/src/typecheck.rs
+++ b/dhall/src/typecheck.rs
@@ -4,12 +4,12 @@ use std::collections::HashSet;
 use std::fmt;
 
 use crate::context::Context;
-use crate::core;
-use crate::core::Builtin::*;
-use crate::core::Const::*;
-use crate::core::Expr::*;
-use crate::core::{app, pi};
-use crate::core::{bx, normalize, shift, subst, Expr, V, X};
+use dhall_core::core;
+use dhall_core::core::Builtin::*;
+use dhall_core::core::Const::*;
+use dhall_core::core::Expr::*;
+use dhall_core::core::{app, pi};
+use dhall_core::core::{bx, normalize, shift, subst, Expr, V, X};
 
 use self::TypeMessage::*;
 
@@ -184,7 +184,7 @@ pub fn type_with<'i, S>(
 where
     S: Clone + ::std::fmt::Debug + 'i,
 {
-    use crate::BinOp::*;
+    use dhall_core::BinOp::*;
     match *e {
         Const(c) => axiom(c).map(Const), //.map(Cow::Owned),
         Var(V(x, n)) => {
diff --git a/dhall/tests/macros.rs b/dhall/tests/macros.rs
index 66b9dbf..777a2f6 100644
--- a/dhall/tests/macros.rs
+++ b/dhall/tests/macros.rs
@@ -91,6 +91,7 @@ macro_rules! make_spec_test {
         #[allow(unused_imports)]
         fn $name() {
             use dhall::*;
+            use dhall_core::*;
             use std::thread;
 
             thread::Builder::new()