oops

4 files changed, 497 insertions, 0 deletions

diff --git a/dhall_core/src/import.rs b/dhall_core/src/import.rs
new file mode 100644
index 0000000..3e2fbe8
--- /dev/null
+++ b/dhall_core/src/import.rs
@@ -0,0 +1,38 @@
+use std::path::PathBuf;
+
+/// The beginning of a file path which anchors subsequent path components
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum FilePrefix {
+    /// Absolute path
+    Absolute,
+    /// Path relative to .
+    Here,
+    /// Path relative to ..
+    Parent,
+    /// Path relative to ~
+    Home,
+}
+
+/// The location of import (i.e. local vs. remote vs. environment)
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum ImportLocation {
+    Local(FilePrefix, PathBuf),
+    // TODO: other import types
+}
+
+/// How to interpret the import's contents (i.e. as Dhall code or raw text)
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum ImportMode {
+    Code,
+    // TODO
+    // RawText,
+}
+
+/// Reference to an external resource
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Import {
+    pub mode: ImportMode,
+    pub location: ImportLocation,
+    // TODO
+    pub hash: Option<()>,
+}
diff --git a/dhall_core/src/label.rs b/dhall_core/src/label.rs
new file mode 100644
index 0000000..3633b93
--- /dev/null
+++ b/dhall_core/src/label.rs
@@ -0,0 +1,38 @@
+use std::fmt::{self, Display};
+use std::rc::Rc;
+
+// The type for labels throughout the AST
+// It owns the data because otherwise lifetimes would make recursive imports impossible
+#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub struct Label(Rc<str>);
+
+impl From<String> for Label {
+    fn from(s: String) -> Self {
+        let s: &str = &s;
+        Label(s.into())
+    }
+}
+
+impl<'a> From<&'a str> for Label {
+    fn from(s: &'a str) -> Self {
+        Label(Rc::from(s))
+    }
+}
+
+impl From<Label> for String {
+    fn from(x: Label) -> String {
+        x.0.as_ref().to_owned()
+    }
+}
+
+impl Display for Label {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        self.0.as_ref().fmt(f)
+    }
+}
+
+impl Label {
+    pub fn from_str(s: &str) -> Label {
+        Label(s.into())
+    }
+}
diff --git a/dhall_core/src/printer.rs b/dhall_core/src/printer.rs
new file mode 100644
index 0000000..b72f32b
--- /dev/null
+++ b/dhall_core/src/printer.rs
@@ -0,0 +1,329 @@
+use crate::*;
+use std::fmt::{self, Display};
+
+//  There used to be a one-to-one correspondence between the formatters in this section
+//  and the grammar.  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.
+//
+//  WARNING: 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<S, A: Display> Display for Expr<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<S, A: Display> Expr<S, A> {
+    fn fmt_b(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        use crate::Expr::*;
+        match self {
+            &Lam(ref 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)
+            }
+            // TODO: wait for decision on label types
+            // &Pi("_", ref b, ref c) => {
+            //     b.fmt_c(f)?;
+            //     write!(f, " → ")?;
+            //     c.fmt_b(f)
+            // }
+            &Pi(ref a, ref b, ref c) => {
+                write!(f, "∀({} : ", a)?;
+                b.fmt(f)?;
+                write!(f, ") → ")?;
+                c.fmt_b(f)
+            }
+            &Let(ref a, None, ref c, ref d) => {
+                write!(f, "let {} = ", a)?;
+                c.fmt(f)?;
+                write!(f, " in ")?;
+                d.fmt_b(f)
+            }
+            &Let(ref a, Some(ref b), ref c, ref d) => {
+                write!(f, "let {} : ", a)?;
+                b.fmt(f)?;
+                write!(f, " = ")?;
+                c.fmt(f)?;
+                write!(f, " in ")?;
+                d.fmt_b(f)
+            }
+            &EmptyListLit(ref t) => {
+                write!(f, "[] : List ")?;
+                t.fmt_e(f)
+            }
+            &NEListLit(ref es) => {
+                fmt_list("[", ", ", "]", es, f, |e, f| e.fmt(f))
+            }
+            &EmptyOptionalLit(ref t) => {
+                write!(f, "None ")?;
+                t.fmt_e(f)?;
+                Ok(())
+            }
+            &NEOptionalLit(ref e) => {
+                write!(f, "Some ")?;
+                e.fmt_e(f)?;
+                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(op, ref a, ref b) => {
+                write!(f, "(")?;
+                a.fmt_d(f)?;
+                write!(
+                    f,
+                    " {} ",
+                    match op {
+                        BoolOr => "||",
+                        TextAppend => "++",
+                        NaturalPlus => "+",
+                        BoolAnd => "&&",
+                        Combine => "/\\",
+                        NaturalTimes => "*",
+                        BoolEQ => "==",
+                        BoolNE => "!=",
+                        CombineTypes => "//\\\\",
+                        ImportAlt => "?",
+                        Prefer => "//",
+                        ListAppend => "#",
+                    }
+                )?;
+                b.fmt_c(f)?;
+                write!(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 args) => {
+                a.fmt_d(f)?;
+                for x in args {
+                    f.write_str(" ")?;
+                    x.fmt_e(f)?;
+                }
+                Ok(())
+            }
+            &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, ref 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"),
+            &NaturalLit(a) => a.fmt(f),
+            &IntegerLit(a) if *a >= 0 => {
+                f.write_str("+")?;
+                a.fmt(f)
+            }
+            &IntegerLit(a) => a.fmt(f),
+            &DoubleLit(a) => a.fmt(f),
+            &TextLit(ref a) => {
+                f.write_str("\"")?;
+                for x in a.iter() {
+                    match x {
+                        InterpolatedTextContents::Text(a) => {
+                            // TODO Format all escapes properly
+                            f.write_str(
+                                &a.replace("\n", "\\n")
+                                    .replace("\t", "\\t")
+                                    .replace("\r", "\\r")
+                                    .replace("\"", "\\\""),
+                            )?;
+                        }
+                        InterpolatedTextContents::Expr(e) => {
+                            f.write_str("${ ")?;
+                            e.fmt(f)?;
+                            f.write_str(" }")?;
+                        }
+                    }
+                }
+                f.write_str("\"")?;
+                Ok(())
+            }
+            &RecordType(ref a) if a.is_empty() => f.write_str("{}"),
+            &RecordType(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)
+                })
+            }
+            &UnionType(ref a) => {
+                fmt_list("< ", " | ", " >", a, f, |(k, v), f| {
+                    write!(f, "{} : {}", k, v)
+                })
+            }
+            &UnionLit(ref a, ref b, ref c) => {
+                f.write_str("< ")?;
+                write!(f, "{} = {}", a, b)?;
+                for (k, v) in c {
+                    f.write_str(" | ")?;
+                    write!(f, "{} : {}", k, v)?;
+                }
+                f.write_str(" >")
+            }
+            &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,
+    sep: &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(sep)?;
+        }
+        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 Import {
+    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",
+            OptionalSome => "Some",
+            OptionalNone => "None",
+            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 Display for V {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        let V(ref x, ref n) = *self;
+        x.fmt(f)?;
+        if *n != 0 {
+            write!(f, "@{}", n)?;
+        }
+        Ok(())
+    }
+}
+
+impl Display for X {
+    fn fmt(&self, _: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        match *self {}
+    }
+}
diff --git a/dhall_core/src/text.rs b/dhall_core/src/text.rs
new file mode 100644
index 0000000..cd5fef3
--- /dev/null
+++ b/dhall_core/src/text.rs
@@ -0,0 +1,92 @@
+use crate::*;
+use std::iter::FromIterator;
+use std::ops::Add;
+use std::rc::Rc;
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct InterpolatedText<Note, Embed> {
+    head: String,
+    tail: Vec<(Rc<Expr<Note, Embed>>, String)>,
+}
+
+impl<N, E> From<(String, Vec<(Rc<Expr<N, E>>, String)>)>
+    for InterpolatedText<N, E>
+{
+    fn from(x: (String, Vec<(Rc<Expr<N, E>>, String)>)) -> Self {
+        InterpolatedText {
+            head: x.0,
+            tail: x.1,
+        }
+    }
+}
+
+impl<N, E> From<String> for InterpolatedText<N, E> {
+    fn from(s: String) -> Self {
+        InterpolatedText {
+            head: s,
+            tail: vec![],
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+pub enum InterpolatedTextContents<'a, Note, Embed> {
+    Text(&'a str),
+    Expr(SubExpr<Note, Embed>),
+}
+
+impl<N, E> InterpolatedText<N, E> {
+    pub fn map<N2, E2, F>(&self, mut f: F) -> InterpolatedText<N2, E2>
+    where
+        F: FnMut(&Rc<Expr<N, E>>) -> Rc<Expr<N2, E2>>,
+    {
+        InterpolatedText {
+            head: self.head.clone(),
+            tail: self.tail.iter().map(|(e, s)| (f(e), s.clone())).collect(),
+        }
+    }
+
+    pub fn iter(&self) -> impl Iterator<Item = InterpolatedTextContents<N, E>> {
+        use std::iter::once;
+        once(InterpolatedTextContents::Text(self.head.as_ref())).chain(
+            self.tail.iter().flat_map(|(e, s)| {
+                once(InterpolatedTextContents::Expr(Rc::clone(e)))
+                    .chain(once(InterpolatedTextContents::Text(s)))
+            }),
+        )
+    }
+}
+
+impl<'a, N: 'a, E: 'a> FromIterator<InterpolatedTextContents<'a, N, E>>
+    for InterpolatedText<N, E>
+{
+    fn from_iter<T>(iter: T) -> Self
+    where
+        T: IntoIterator<Item = InterpolatedTextContents<'a, N, E>>,
+    {
+        let mut res = InterpolatedText {
+            head: "".to_owned(),
+            tail: vec![],
+        };
+        // let mut empty_string = "".to_owned();
+        let mut crnt_str = &mut res.head;
+        for x in iter.into_iter() {
+            match x {
+                InterpolatedTextContents::Text(s) => crnt_str.push_str(s),
+                InterpolatedTextContents::Expr(e) => {
+                    // crnt_str = &mut empty_string;
+                    res.tail.push((e.clone(), "".to_owned()));
+                    crnt_str = &mut res.tail.last_mut().unwrap().1;
+                }
+            }
+        }
+        res
+    }
+}
+
+impl<N, E> Add for &InterpolatedText<N, E> {
+    type Output = InterpolatedText<N, E>;
+    fn add(self, rhs: &InterpolatedText<N, E>) -> Self::Output {
+        self.iter().chain(rhs.iter()).collect()
+    }
+}