Move contents of dhall_syntax to dhall

1 files changed, 0 insertions, 942 deletions

diff --git a/dhall_syntax/src/parser.rs b/dhall_syntax/src/parser.rs
deleted file mode 100644
index 044d3f1..0000000
--- a/dhall_syntax/src/parser.rs
+++ /dev/null
@@ -1,942 +0,0 @@
-use itertools::Itertools;
-use pest::prec_climber as pcl;
-use pest::prec_climber::PrecClimber;
-use std::rc::Rc;
-
-use pest_consume::{match_nodes, Parser};
-
-use crate::map::{DupTreeMap, DupTreeSet};
-use crate::ExprF::*;
-use crate::*;
-
-// This file consumes the parse tree generated by pest and turns it into
-// our own AST. All those custom macros should eventually moved into
-// their own crate because they are quite general and useful. For now they
-// are here and hopefully you can figure out how they work.
-
-type ParsedText<E> = InterpolatedText<Expr<E>>;
-type ParsedTextContents<E> = InterpolatedTextContents<Expr<E>>;
-type ParseInput<'input> = pest_consume::Node<'input, Rule, Rc<str>>;
-
-pub type ParseError = pest::error::Error<Rule>;
-pub type ParseResult<T> = Result<T, ParseError>;
-
-#[derive(Debug)]
-enum Selector<E> {
-    Field(Label),
-    Projection(DupTreeSet<Label>),
-    ProjectionByExpr(Expr<E>),
-}
-
-impl crate::Builtin {
-    pub fn parse(s: &str) -> Option<Self> {
-        use crate::Builtin::*;
-        match s {
-            "Bool" => Some(Bool),
-            "Natural" => Some(Natural),
-            "Integer" => Some(Integer),
-            "Double" => Some(Double),
-            "Text" => Some(Text),
-            "List" => Some(List),
-            "Optional" => Some(Optional),
-            "None" => Some(OptionalNone),
-            "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),
-            "Natural/subtract" => Some(NaturalSubtract),
-            "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,
-        }
-    }
-}
-
-fn input_to_span(input: ParseInput) -> Span {
-    Span::make(input.user_data().clone(), input.as_pair().as_span())
-}
-fn spanned<E>(input: ParseInput, x: RawExpr<E>) -> Expr<E> {
-    Expr::new(x, input_to_span(input))
-}
-fn spanned_union<E>(span1: Span, span2: Span, x: RawExpr<E>) -> Expr<E> {
-    Expr::new(x, span1.union(&span2))
-}
-
-// Trim the shared indent off of a vec of lines, as defined by the Dhall semantics of multiline
-// literals.
-fn trim_indent<E: Clone>(lines: &mut Vec<ParsedText<E>>) {
-    let is_indent = |c: char| c == ' ' || c == '\t';
-
-    // There is at least one line so this is safe
-    let last_line_head = lines.last().unwrap().head();
-    let indent_chars = last_line_head
-        .char_indices()
-        .take_while(|(_, c)| is_indent(*c));
-    let mut min_indent_idx = match indent_chars.last() {
-        Some((i, _)) => i,
-        // If there is no indent char, then no indent needs to be stripped
-        None => return,
-    };
-
-    for line in lines.iter() {
-        // Ignore empty lines
-        if line.is_empty() {
-            continue;
-        }
-        // Take chars from line while they match the current minimum indent.
-        let indent_chars = last_line_head[0..=min_indent_idx]
-            .char_indices()
-            .zip(line.head().chars())
-            .take_while(|((_, c1), c2)| c1 == c2);
-        match indent_chars.last() {
-            Some(((i, _), _)) => min_indent_idx = i,
-            // If there is no indent char, then no indent needs to be stripped
-            None => return,
-        };
-    }
-
-    // Remove the shared indent from non-empty lines
-    for line in lines.iter_mut() {
-        if !line.is_empty() {
-            line.head_mut().replace_range(0..=min_indent_idx, "");
-        }
-    }
-}
-
-lazy_static::lazy_static! {
-    static ref PRECCLIMBER: PrecClimber<Rule> = {
-        use Rule::*;
-        // In order of precedence
-        let operators = vec![
-            import_alt,
-            bool_or,
-            natural_plus,
-            text_append,
-            list_append,
-            bool_and,
-            combine,
-            prefer,
-            combine_types,
-            natural_times,
-            bool_eq,
-            bool_ne,
-            equivalent,
-        ];
-        PrecClimber::new(
-            operators
-                .into_iter()
-                .map(|op| pcl::Operator::new(op, pcl::Assoc::Left))
-                .collect(),
-        )
-    };
-}
-
-#[derive(Parser)]
-#[grammar = "dhall.pest"]
-struct DhallParser;
-
-#[pest_consume::parser(parser = DhallParser, rule = Rule)]
-impl DhallParser {
-    fn EOI(_input: ParseInput) -> ParseResult<()> {
-        Ok(())
-    }
-
-    #[alias(label)]
-    fn simple_label(input: ParseInput) -> ParseResult<Label> {
-        Ok(Label::from(input.as_str()))
-    }
-    #[alias(label)]
-    fn quoted_label(input: ParseInput) -> ParseResult<Label> {
-        Ok(Label::from(input.as_str()))
-    }
-
-    fn double_quote_literal<E: Clone>(
-        input: ParseInput,
-    ) -> ParseResult<ParsedText<E>> {
-        Ok(match_nodes!(input.into_children();
-            [double_quote_chunk(chunks)..] => {
-                chunks.collect()
-            }
-        ))
-    }
-
-    fn double_quote_chunk<E: Clone>(
-        input: ParseInput,
-    ) -> ParseResult<ParsedTextContents<E>> {
-        Ok(match_nodes!(input.into_children();
-            [expression(e)] => {
-                InterpolatedTextContents::Expr(e)
-            },
-            [double_quote_char(s)] => {
-                InterpolatedTextContents::Text(s)
-            },
-        ))
-    }
-    #[alias(double_quote_char)]
-    fn double_quote_escaped(input: ParseInput) -> ParseResult<String> {
-        Ok(match input.as_str() {
-            "\"" => "\"".to_owned(),
-            "$" => "$".to_owned(),
-            "\\" => "\\".to_owned(),
-            "/" => "/".to_owned(),
-            "b" => "\u{0008}".to_owned(),
-            "f" => "\u{000C}".to_owned(),
-            "n" => "\n".to_owned(),
-            "r" => "\r".to_owned(),
-            "t" => "\t".to_owned(),
-            // "uXXXX" or "u{XXXXX}"
-            s => {
-                use std::convert::{TryFrom, TryInto};
-
-                let s = &s[1..];
-                let s = if &s[0..1] == "{" {
-                    &s[1..s.len() - 1]
-                } else {
-                    &s[0..s.len()]
-                };
-
-                if s.len() > 8 {
-                    Err(input.error(format!(
-                        "Escape sequences can't have more than 8 chars: \"{}\"",
-                        s
-                    )))?
-                }
-
-                // pad with zeroes
-                let s: String = std::iter::repeat('0')
-                    .take(8 - s.len())
-                    .chain(s.chars())
-                    .collect();
-
-                // `s` has length 8, so `bytes` has length 4
-                let bytes: &[u8] = &hex::decode(s).unwrap();
-                let i = u32::from_be_bytes(bytes.try_into().unwrap());
-                let c = char::try_from(i).unwrap();
-                match i {
-                    0xD800..=0xDFFF => {
-                        let c_ecapsed = c.escape_unicode();
-                        Err(input.error(format!("Escape sequences can't contain surrogate pairs: \"{}\"", c_ecapsed)))?
-                    }
-                    0x0FFFE..=0x0FFFF
-                    | 0x1FFFE..=0x1FFFF
-                    | 0x2FFFE..=0x2FFFF
-                    | 0x3FFFE..=0x3FFFF
-                    | 0x4FFFE..=0x4FFFF
-                    | 0x5FFFE..=0x5FFFF
-                    | 0x6FFFE..=0x6FFFF
-                    | 0x7FFFE..=0x7FFFF
-                    | 0x8FFFE..=0x8FFFF
-                    | 0x9FFFE..=0x9FFFF
-                    | 0xAFFFE..=0xAFFFF
-                    | 0xBFFFE..=0xBFFFF
-                    | 0xCFFFE..=0xCFFFF
-                    | 0xDFFFE..=0xDFFFF
-                    | 0xEFFFE..=0xEFFFF
-                    | 0xFFFFE..=0xFFFFF
-                    | 0x10_FFFE..=0x10_FFFF => {
-                        let c_ecapsed = c.escape_unicode();
-                        Err(input.error(format!("Escape sequences can't contain non-characters: \"{}\"", c_ecapsed)))?
-                    }
-                    _ => {}
-                }
-                std::iter::once(c).collect()
-            }
-        })
-    }
-    fn double_quote_char(input: ParseInput) -> ParseResult<String> {
-        Ok(input.as_str().to_owned())
-    }
-
-    fn single_quote_literal<E: Clone>(
-        input: ParseInput,
-    ) -> ParseResult<ParsedText<E>> {
-        Ok(match_nodes!(input.into_children();
-            [single_quote_continue(lines)] => {
-                let newline: ParsedText<E> = "\n".to_string().into();
-
-                // Reverse lines and chars in each line
-                let mut lines: Vec<ParsedText<E>> = lines
-                    .into_iter()
-                    .rev()
-                    .map(|l| l.into_iter().rev().collect::<ParsedText<E>>())
-                    .collect();
-
-                trim_indent(&mut lines);
-
-                lines
-                    .into_iter()
-                    .intersperse(newline)
-                    .flat_map(InterpolatedText::into_iter)
-                    .collect::<ParsedText<E>>()
-            }
-        ))
-    }
-    fn single_quote_char(input: ParseInput) -> ParseResult<&str> {
-        Ok(input.as_str())
-    }
-    #[alias(single_quote_char)]
-    fn escaped_quote_pair(_input: ParseInput) -> ParseResult<&str> {
-        Ok("''")
-    }
-    #[alias(single_quote_char)]
-    fn escaped_interpolation(_input: ParseInput) -> ParseResult<&str> {
-        Ok("${")
-    }
-
-    // Returns a vec of lines in reversed order, where each line is also in reversed order.
-    fn single_quote_continue<E: Clone>(
-        input: ParseInput,
-    ) -> ParseResult<Vec<Vec<ParsedTextContents<E>>>> {
-        Ok(match_nodes!(input.into_children();
-            [expression(e), single_quote_continue(lines)] => {
-                let c = InterpolatedTextContents::Expr(e);
-                let mut lines = lines;
-                lines.last_mut().unwrap().push(c);
-                lines
-            },
-            [single_quote_char(c), single_quote_continue(lines)] => {
-                let mut lines = lines;
-                if c == "\n" || c == "\r\n" {
-                    lines.push(vec![]);
-                } else {
-                    // TODO: don't allocate for every char
-                    let c = InterpolatedTextContents::Text(c.to_owned());
-                    lines.last_mut().unwrap().push(c);
-                }
-                lines
-            },
-            [] => {
-                vec![vec![]]
-            },
-        ))
-    }
-
-    #[alias(expression)]
-    fn builtin<E: Clone>(input: ParseInput) -> ParseResult<Expr<E>> {
-        let s = input.as_str();
-        let e = match crate::Builtin::parse(s) {
-            Some(b) => Builtin(b),
-            None => match s {
-                "True" => BoolLit(true),
-                "False" => BoolLit(false),
-                "Type" => Const(crate::Const::Type),
-                "Kind" => Const(crate::Const::Kind),
-                "Sort" => Const(crate::Const::Sort),
-                _ => {
-                    Err(input.error(format!("Unrecognized builtin: '{}'", s)))?
-                }
-            },
-        };
-        Ok(spanned(input, e))
-    }
-
-    #[alias(double_literal)]
-    fn NaN(_input: ParseInput) -> ParseResult<core::Double> {
-        Ok(std::f64::NAN.into())
-    }
-    #[alias(double_literal)]
-    fn minus_infinity_literal(_input: ParseInput) -> ParseResult<core::Double> {
-        Ok(std::f64::NEG_INFINITY.into())
-    }
-    #[alias(double_literal)]
-    fn plus_infinity_literal(_input: ParseInput) -> ParseResult<core::Double> {
-        Ok(std::f64::INFINITY.into())
-    }
-
-    #[alias(double_literal)]
-    fn numeric_double_literal(input: ParseInput) -> ParseResult<core::Double> {
-        let s = input.as_str().trim();
-        match s.parse::<f64>() {
-            Ok(x) if x.is_infinite() => Err(input.error(format!(
-                "Overflow while parsing double literal '{}'",
-                s
-            ))),
-            Ok(x) => Ok(NaiveDouble::from(x)),
-            Err(e) => Err(input.error(format!("{}", e))),
-        }
-    }
-
-    fn natural_literal(input: ParseInput) -> ParseResult<core::Natural> {
-        input
-            .as_str()
-            .trim()
-            .parse()
-            .map_err(|e| input.error(format!("{}", e)))
-    }
-
-    fn integer_literal(input: ParseInput) -> ParseResult<core::Integer> {
-        input
-            .as_str()
-            .trim()
-            .parse()
-            .map_err(|e| input.error(format!("{}", e)))
-    }
-
-    #[alias(expression, shortcut = true)]
-    fn identifier<E: Clone>(input: ParseInput) -> ParseResult<Expr<E>> {
-        Ok(match_nodes!(input.children();
-            [variable(v)] => spanned(input, Var(v)),
-            [expression(e)] => e,
-        ))
-    }
-
-    fn variable(input: ParseInput) -> ParseResult<V<Label>> {
-        Ok(match_nodes!(input.into_children();
-            [label(l), natural_literal(idx)] => V(l, idx),
-            [label(l)] => V(l, 0),
-        ))
-    }
-
-    #[alias(path_component)]
-    fn unquoted_path_component(input: ParseInput) -> ParseResult<String> {
-        Ok(input.as_str().to_string())
-    }
-    #[alias(path_component)]
-    fn quoted_path_component(input: ParseInput) -> ParseResult<String> {
-        #[rustfmt::skip]
-        const RESERVED: &percent_encoding::AsciiSet =
-            &percent_encoding::CONTROLS
-            .add(b'=').add(b':').add(b'/').add(b'?')
-            .add(b'#').add(b'[').add(b']').add(b'@')
-            .add(b'!').add(b'$').add(b'&').add(b'\'')
-            .add(b'(').add(b')').add(b'*').add(b'+')
-            .add(b',').add(b';');
-        Ok(input
-            .as_str()
-            .chars()
-            .map(|c| {
-                // Percent-encode ascii chars
-                if c.is_ascii() {
-                    percent_encoding::utf8_percent_encode(
-                        &c.to_string(),
-                        RESERVED,
-                    )
-                    .to_string()
-                } else {
-                    c.to_string()
-                }
-            })
-            .collect())
-    }
-    fn path(input: ParseInput) -> ParseResult<FilePath> {
-        Ok(match_nodes!(input.into_children();
-            [path_component(components)..] => {
-                FilePath { file_path: components.collect() }
-            }
-        ))
-    }
-
-    #[alias(import_type)]
-    fn local<E: Clone>(
-        input: ParseInput,
-    ) -> ParseResult<ImportLocation<Expr<E>>> {
-        Ok(match_nodes!(input.into_children();
-            [local_path((prefix, p))] => ImportLocation::Local(prefix, p),
-        ))
-    }
-
-    #[alias(local_path)]
-    fn parent_path(input: ParseInput) -> ParseResult<(FilePrefix, FilePath)> {
-        Ok(match_nodes!(input.into_children();
-            [path(p)] => (FilePrefix::Parent, p)
-        ))
-    }
-    #[alias(local_path)]
-    fn here_path(input: ParseInput) -> ParseResult<(FilePrefix, FilePath)> {
-        Ok(match_nodes!(input.into_children();
-            [path(p)] => (FilePrefix::Here, p)
-        ))
-    }
-    #[alias(local_path)]
-    fn home_path(input: ParseInput) -> ParseResult<(FilePrefix, FilePath)> {
-        Ok(match_nodes!(input.into_children();
-            [path(p)] => (FilePrefix::Home, p)
-        ))
-    }
-    #[alias(local_path)]
-    fn absolute_path(input: ParseInput) -> ParseResult<(FilePrefix, FilePath)> {
-        Ok(match_nodes!(input.into_children();
-            [path(p)] => (FilePrefix::Absolute, p)
-        ))
-    }
-
-    fn scheme(input: ParseInput) -> ParseResult<Scheme> {
-        Ok(match input.as_str() {
-            "http" => Scheme::HTTP,
-            "https" => Scheme::HTTPS,
-            _ => unreachable!(),
-        })
-    }
-
-    fn http_raw<E: Clone>(input: ParseInput) -> ParseResult<URL<Expr<E>>> {
-        Ok(match_nodes!(input.into_children();
-            [scheme(sch), authority(auth), path(p)] => URL {
-                scheme: sch,
-                authority: auth,
-                path: p,
-                query: None,
-                headers: None,
-            },
-            [scheme(sch), authority(auth), path(p), query(q)] => URL {
-                scheme: sch,
-                authority: auth,
-                path: p,
-                query: Some(q),
-                headers: None,
-            },
-        ))
-    }
-
-    fn authority(input: ParseInput) -> ParseResult<String> {
-        Ok(input.as_str().to_owned())
-    }
-
-    fn query(input: ParseInput) -> ParseResult<String> {
-        Ok(input.as_str().to_owned())
-    }
-
-    #[alias(import_type)]
-    fn http<E: Clone>(
-        input: ParseInput,
-    ) -> ParseResult<ImportLocation<Expr<E>>> {
-        Ok(ImportLocation::Remote(match_nodes!(input.into_children();
-            [http_raw(url)] => url,
-            [http_raw(url), expression(e)] => URL { headers: Some(e), ..url },
-        )))
-    }
-
-    #[alias(import_type)]
-    fn env<E: Clone>(
-        input: ParseInput,
-    ) -> ParseResult<ImportLocation<Expr<E>>> {
-        Ok(match_nodes!(input.into_children();
-            [environment_variable(v)] => ImportLocation::Env(v),
-        ))
-    }
-    #[alias(environment_variable)]
-    fn bash_environment_variable(input: ParseInput) -> ParseResult<String> {
-        Ok(input.as_str().to_owned())
-    }
-    #[alias(environment_variable)]
-    fn posix_environment_variable(input: ParseInput) -> ParseResult<String> {
-        Ok(match_nodes!(input.into_children();
-            [posix_environment_variable_character(chars)..] => {
-                chars.collect()
-            },
-        ))
-    }
-    fn posix_environment_variable_character(
-        input: ParseInput,
-    ) -> ParseResult<&str> {
-        Ok(match input.as_str() {
-            "\\\"" => "\"",
-            "\\\\" => "\\",
-            "\\a" => "\u{0007}",
-            "\\b" => "\u{0008}",
-            "\\f" => "\u{000C}",
-            "\\n" => "\n",
-            "\\r" => "\r",
-            "\\t" => "\t",
-            "\\v" => "\u{000B}",
-            s => s,
-        })
-    }
-
-    #[alias(import_type)]
-    fn missing<E: Clone>(
-        _input: ParseInput,
-    ) -> ParseResult<ImportLocation<Expr<E>>> {
-        Ok(ImportLocation::Missing)
-    }
-
-    fn hash(input: ParseInput) -> ParseResult<Hash> {
-        let s = input.as_str().trim();
-        let protocol = &s[..6];
-        let hash = &s[7..];
-        if protocol != "sha256" {
-            Err(input.error(format!("Unknown hashing protocol '{}'", protocol)))?
-        }
-        Ok(Hash::SHA256(hex::decode(hash).unwrap()))
-    }
-
-    fn import_hashed<E: Clone>(
-        input: ParseInput,
-    ) -> ParseResult<crate::Import<Expr<E>>> {
-        use crate::Import;
-        let mode = ImportMode::Code;
-        Ok(match_nodes!(input.into_children();
-            [import_type(location)] => Import { mode, location, hash: None },
-            [import_type(location), hash(h)] => Import { mode, location, hash: Some(h) },
-        ))
-    }
-
-    #[alias(import_mode)]
-    fn Text(_input: ParseInput) -> ParseResult<ImportMode> {
-        Ok(ImportMode::RawText)
-    }
-    #[alias(import_mode)]
-    fn Location(_input: ParseInput) -> ParseResult<ImportMode> {
-        Ok(ImportMode::Location)
-    }
-
-    #[alias(expression)]
-    fn import<E: Clone>(input: ParseInput) -> ParseResult<Expr<E>> {
-        use crate::Import;
-        let import = match_nodes!(input.children();
-            [import_hashed(imp)] => {
-                Import { mode: ImportMode::Code, ..imp }
-            },
-            [import_hashed(imp), import_mode(mode)] => {
-                Import { mode, ..imp }
-            },
-        );
-        Ok(spanned(input, Import(import)))
-    }
-
-    fn lambda(_input: ParseInput) -> ParseResult<()> {
-        Ok(())
-    }
-    fn forall(_input: ParseInput) -> ParseResult<()> {
-        Ok(())
-    }
-    fn arrow(_input: ParseInput) -> ParseResult<()> {
-        Ok(())
-    }
-    fn merge(_input: ParseInput) -> ParseResult<()> {
-        Ok(())
-    }
-    fn assert(_input: ParseInput) -> ParseResult<()> {
-        Ok(())
-    }
-    fn if_(_input: ParseInput) -> ParseResult<()> {
-        Ok(())
-    }
-    fn toMap(_input: ParseInput) -> ParseResult<()> {
-        Ok(())
-    }
-
-    #[alias(expression)]
-    fn empty_list_literal<E: Clone>(input: ParseInput) -> ParseResult<Expr<E>> {
-        Ok(match_nodes!(input.children();
-            [expression(e)] => spanned(input, EmptyListLit(e)),
-        ))
-    }
-
-    fn expression<E: Clone>(input: ParseInput) -> ParseResult<Expr<E>> {
-        Ok(match_nodes!(input.children();
-            [lambda(()), label(l), expression(typ),
-                    arrow(()), expression(body)] => {
-                spanned(input, Lam(l, typ, body))
-            },
-            [if_(()), expression(cond), expression(left),
-                    expression(right)] => {
-                spanned(input, BoolIf(cond, left, right))
-            },
-            [let_binding(bindings).., expression(final_expr)] => {
-                bindings.rev().fold(
-                    final_expr,
-                    |acc, x| {
-                        spanned_union(
-                            acc.span(),
-                            x.3,
-                            Let(x.0, x.1, x.2, acc)
-                        )
-                    }
-                )
-            },
-            [forall(()), label(l), expression(typ),
-                    arrow(()), expression(body)] => {
-                spanned(input, Pi(l, typ, body))
-            },
-            [expression(typ), arrow(()), expression(body)] => {
-                spanned(input, Pi("_".into(), typ, body))
-            },
-            [merge(()), expression(x), expression(y), expression(z)] => {
-                spanned(input, Merge(x, y, Some(z)))
-            },
-            [assert(()), expression(x)] => {
-                spanned(input, Assert(x))
-            },
-            [toMap(()), expression(x), expression(y)] => {
-                spanned(input, ToMap(x, Some(y)))
-            },
-            [expression(e), expression(annot)] => {
-                spanned(input, Annot(e, annot))
-            },
-            [expression(e)] => e,
-        ))
-    }
-
-    fn let_binding<E: Clone>(
-        input: ParseInput,
-    ) -> ParseResult<(Label, Option<Expr<E>>, Expr<E>, Span)> {
-        Ok(match_nodes!(input.children();
-            [label(name), expression(annot), expression(expr)] =>
-                (name, Some(annot), expr, input_to_span(input)),
-            [label(name), expression(expr)] =>
-                (name, None, expr, input_to_span(input)),
-        ))
-    }
-
-    #[alias(expression, shortcut = true)]
-    #[prec_climb(expression, PRECCLIMBER)]
-    fn operator_expression<E: Clone>(
-        l: Expr<E>,
-        op: ParseInput,
-        r: Expr<E>,
-    ) -> ParseResult<Expr<E>> {
-        use crate::BinOp::*;
-        use Rule::*;
-        let op = match op.as_rule() {
-            import_alt => ImportAlt,
-            bool_or => BoolOr,
-            natural_plus => NaturalPlus,
-            text_append => TextAppend,
-            list_append => ListAppend,
-            bool_and => BoolAnd,
-            combine => RecursiveRecordMerge,
-            prefer => RightBiasedRecordMerge,
-            combine_types => RecursiveRecordTypeMerge,
-            natural_times => NaturalTimes,
-            bool_eq => BoolEQ,
-            bool_ne => BoolNE,
-            equivalent => Equivalence,
-            r => Err(op.error(format!("Rule {:?} isn't an operator", r)))?,
-        };
-
-        Ok(spanned_union(l.span(), r.span(), BinOp(op, l, r)))
-    }
-
-    fn Some_(_input: ParseInput) -> ParseResult<()> {
-        Ok(())
-    }
-
-    #[alias(expression, shortcut = true)]
-    fn application_expression<E: Clone>(
-        input: ParseInput,
-    ) -> ParseResult<Expr<E>> {
-        Ok(match_nodes!(input.children();
-            [expression(e)] => e,
-            [expression(first), expression(rest)..] => {
-                rest.fold(
-                    first,
-                    |acc, e| {
-                        spanned_union(
-                            acc.span(),
-                            e.span(),
-                            App(acc, e)
-                        )
-                    }
-                )
-            },
-        ))
-    }
-
-    #[alias(expression, shortcut = true)]
-    fn first_application_expression<E: Clone>(
-        input: ParseInput,
-    ) -> ParseResult<Expr<E>> {
-        Ok(match_nodes!(input.children();
-            [Some_(()), expression(e)] => {
-                spanned(input, SomeLit(e))
-            },
-            [merge(()), expression(x), expression(y)] => {
-                spanned(input, Merge(x, y, None))
-            },
-            [toMap(()), expression(x)] => {
-                spanned(input, ToMap(x, None))
-            },
-            [expression(e)] => e,
-        ))
-    }
-
-    #[alias(expression, shortcut = true)]
-    fn selector_expression<E: Clone>(
-        input: ParseInput,
-    ) -> ParseResult<Expr<E>> {
-        Ok(match_nodes!(input.children();
-            [expression(e)] => e,
-            [expression(first), selector(rest)..] => {
-                rest.fold(
-                    first,
-                    |acc, e| {
-                        spanned_union(
-                            acc.span(),
-                            e.1,
-                            match e.0 {
-                                Selector::Field(l) => Field(acc, l),
-                                Selector::Projection(ls) => Projection(acc, ls),
-                                Selector::ProjectionByExpr(e) => ProjectionByExpr(acc, e)
-                            }
-                        )
-                    }
-                )
-            },
-        ))
-    }
-
-    fn selector<E: Clone>(
-        input: ParseInput,
-    ) -> ParseResult<(Selector<E>, Span)> {
-        let stor = match_nodes!(input.children();
-            [label(l)] => Selector::Field(l),
-            [labels(ls)] => Selector::Projection(ls),
-            [expression(e)] => Selector::ProjectionByExpr(e),
-        );
-        Ok((stor, input_to_span(input)))
-    }
-
-    fn labels(input: ParseInput) -> ParseResult<DupTreeSet<Label>> {
-        Ok(match_nodes!(input.into_children();
-            [label(ls)..] => ls.collect(),
-        ))
-    }
-
-    #[alias(expression, shortcut = true)]
-    fn primitive_expression<E: Clone>(
-        input: ParseInput,
-    ) -> ParseResult<Expr<E>> {
-        Ok(match_nodes!(input.children();
-            [double_literal(n)] => spanned(input, DoubleLit(n)),
-            [natural_literal(n)] => spanned(input, NaturalLit(n)),
-            [integer_literal(n)] => spanned(input, IntegerLit(n)),
-            [double_quote_literal(s)] => spanned(input, TextLit(s)),
-            [single_quote_literal(s)] => spanned(input, TextLit(s)),
-            [expression(e)] => e,
-        ))
-    }
-
-    #[alias(expression)]
-    fn empty_record_literal<E: Clone>(
-        input: ParseInput,
-    ) -> ParseResult<Expr<E>> {
-        Ok(spanned(input, RecordLit(Default::default())))
-    }
-
-    #[alias(expression)]
-    fn empty_record_type<E: Clone>(input: ParseInput) -> ParseResult<Expr<E>> {
-        Ok(spanned(input, RecordType(Default::default())))
-    }
-
-    #[alias(expression)]
-    fn non_empty_record_type_or_literal<E: Clone>(
-        input: ParseInput,
-    ) -> ParseResult<Expr<E>> {
-        let e = match_nodes!(input.children();
-            [label(first_label), non_empty_record_type(rest)] => {
-                let (first_expr, mut map) = rest;
-                map.insert(first_label, first_expr);
-                RecordType(map)
-            },
-            [label(first_label), non_empty_record_literal(rest)] => {
-                let (first_expr, mut map) = rest;
-                map.insert(first_label, first_expr);
-                RecordLit(map)
-            },
-        );
-        Ok(spanned(input, e))
-    }
-
-    fn non_empty_record_type<E: Clone>(
-        input: ParseInput,
-    ) -> ParseResult<(Expr<E>, DupTreeMap<Label, Expr<E>>)> {
-        Ok(match_nodes!(input.into_children();
-            [expression(expr), record_type_entry(entries)..] => {
-                (expr, entries.collect())
-            }
-        ))
-    }
-
-    fn record_type_entry<E: Clone>(
-        input: ParseInput,
-    ) -> ParseResult<(Label, Expr<E>)> {
-        Ok(match_nodes!(input.into_children();
-            [label(name), expression(expr)] => (name, expr)
-        ))
-    }
-
-    fn non_empty_record_literal<E: Clone>(
-        input: ParseInput,
-    ) -> ParseResult<(Expr<E>, DupTreeMap<Label, Expr<E>>)> {
-        Ok(match_nodes!(input.into_children();
-            [expression(expr), record_literal_entry(entries)..] => {
-                (expr, entries.collect())
-            }
-        ))
-    }
-
-    fn record_literal_entry<E: Clone>(
-        input: ParseInput,
-    ) -> ParseResult<(Label, Expr<E>)> {
-        Ok(match_nodes!(input.into_children();
-            [label(name), expression(expr)] => (name, expr)
-        ))
-    }
-
-    #[alias(expression)]
-    fn union_type<E: Clone>(input: ParseInput) -> ParseResult<Expr<E>> {
-        let map = match_nodes!(input.children();
-            [empty_union_type(_)] => Default::default(),
-            [union_type_entry(entries)..] => entries.collect(),
-        );
-        Ok(spanned(input, UnionType(map)))
-    }
-
-    fn empty_union_type(_input: ParseInput) -> ParseResult<()> {
-        Ok(())
-    }
-
-    fn union_type_entry<E: Clone>(
-        input: ParseInput,
-    ) -> ParseResult<(Label, Option<Expr<E>>)> {
-        Ok(match_nodes!(input.children();
-            [label(name), expression(expr)] => (name, Some(expr)),
-            [label(name)] => (name, None),
-        ))
-    }
-
-    #[alias(expression)]
-    fn non_empty_list_literal<E: Clone>(
-        input: ParseInput,
-    ) -> ParseResult<Expr<E>> {
-        Ok(match_nodes!(input.children();
-            [expression(items)..] => spanned(
-                input,
-                NEListLit(items.collect())
-            )
-        ))
-    }
-
-    #[alias(expression)]
-    fn final_expression<E: Clone>(input: ParseInput) -> ParseResult<Expr<E>> {
-        Ok(match_nodes!(input.into_children();
-            [expression(e), EOI(_)] => e
-        ))
-    }
-}
-
-pub fn parse_expr<E: Clone>(input_str: &str) -> ParseResult<Expr<E>> {
-    let rc_input_str = input_str.to_string().into();
-    let inputs = DhallParser::parse_with_userdata(
-        Rule::final_expression,
-        input_str,
-        rc_input_str,
-    )?;
-    Ok(match_nodes!(<DhallParser>; inputs;
-        [expression(e)] => e,
-    ))
-}