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-rw-r--r--dhall/src/core/context.rs33
-rw-r--r--dhall/src/core/thunk.rs52
-rw-r--r--dhall/src/phase/typecheck.rs145
3 files changed, 147 insertions, 83 deletions
diff --git a/dhall/src/core/context.rs b/dhall/src/core/context.rs
index aeec7fb..56dec03 100644
--- a/dhall/src/core/context.rs
+++ b/dhall/src/core/context.rs
@@ -1,4 +1,3 @@
-use std::borrow::Cow;
use std::rc::Rc;
use dhall_syntax::context::Context as SimpleContext;
@@ -25,28 +24,10 @@ pub(crate) struct NormalizationContext(Context<()>);
#[derive(Debug, Clone)]
pub(crate) struct TypecheckContext(Context<Type>);
-impl<T> CtxItem<T> {
- fn forget(&self) -> CtxItem<()> {
- match self {
- CtxItem::Kept(var, _) => CtxItem::Kept(var.clone(), ()),
- CtxItem::Replaced(e, _) => CtxItem::Replaced(e.clone(), ()),
- }
- }
-}
-
impl<T> Context<T> {
pub(crate) fn new() -> Self {
Context(Rc::new(SimpleContext::new()))
}
- pub(crate) fn forget(&self) -> Context<()> {
- let mut ctx = SimpleContext::new();
- for (k, vs) in self.0.iter_keys() {
- for v in vs.iter() {
- ctx = ctx.insert(k.clone(), v.forget());
- }
- }
- Context(Rc::new(ctx))
- }
pub(crate) fn insert_kept(&self, x: &Label, t: T) -> Self
where
T: Shift + Clone,
@@ -103,16 +84,18 @@ impl TypecheckContext {
e.get_type()?.into_owned(),
)))
}
- pub(crate) fn lookup(&self, var: &V<Label>) -> Option<Cow<'_, Type>> {
+ pub(crate) fn lookup(&self, var: &V<Label>) -> Option<Typed> {
match self.0.lookup(var) {
- Some(CtxItem::Kept(_, t)) => Some(Cow::Borrowed(&t)),
- Some(CtxItem::Replaced(_, t)) => Some(Cow::Borrowed(&t)),
+ Some(CtxItem::Kept(newvar, t)) => Some(Typed::from_thunk_and_type(
+ Thunk::from_value(Value::Var(newvar.clone())),
+ t.clone(),
+ )),
+ Some(CtxItem::Replaced(th, t)) => {
+ Some(Typed::from_thunk_and_type(th.clone(), t.clone()))
+ }
None => None,
}
}
- pub(crate) fn to_normalization_ctx(&self) -> NormalizationContext {
- NormalizationContext(self.0.forget())
- }
}
impl<T: Shift> Shift for CtxItem<T> {
diff --git a/dhall/src/core/thunk.rs b/dhall/src/core/thunk.rs
index b3817dc..530762b 100644
--- a/dhall/src/core/thunk.rs
+++ b/dhall/src/core/thunk.rs
@@ -1,13 +1,15 @@
use std::cell::{Ref, RefCell};
use std::rc::Rc;
+use dhall_syntax::{ExprF, Label, X};
+
use crate::core::context::NormalizationContext;
use crate::core::context::TypecheckContext;
use crate::core::value::Value;
use crate::core::var::{AlphaVar, Shift, Subst};
use crate::error::TypeError;
use crate::phase::normalize::{
- apply_any, normalize_whnf, InputSubExpr, OutputSubExpr,
+ apply_any, normalize_one_layer, normalize_whnf, InputSubExpr, OutputSubExpr,
};
use crate::phase::typecheck::mktype;
use crate::phase::{Type, Typed};
@@ -25,6 +27,10 @@ use Marker::{NF, WHNF};
enum ThunkInternal {
/// Non-normalized value alongside a normalization context
Unnormalized(NormalizationContext, InputSubExpr),
+ /// Partially normalized value whose subexpressions have been thunked (this is returned from
+ /// typechecking). Note that this is different from `Value::PartialExpr` because there is no
+ /// requirement of WHNF here.
+ PartialExpr(ExprF<Thunk, Label, X>),
/// Partially normalized value.
/// Invariant: if the marker is `NF`, the value must be fully normalized
Value(Marker, Value),
@@ -57,6 +63,10 @@ impl ThunkInternal {
normalize_whnf(ctx.clone(), e.clone()),
)
}
+ ThunkInternal::PartialExpr(e) => {
+ *self =
+ ThunkInternal::Value(WHNF, normalize_one_layer(e.clone()))
+ }
// Already at least in WHNF
ThunkInternal::Value(_, _) => {}
}
@@ -64,7 +74,8 @@ impl ThunkInternal {
fn normalize_nf(&mut self) {
match self {
- ThunkInternal::Unnormalized(_, _) => {
+ ThunkInternal::Unnormalized(_, _)
+ | ThunkInternal::PartialExpr(_) => {
self.normalize_whnf();
self.normalize_nf();
}
@@ -80,7 +91,8 @@ impl ThunkInternal {
// Always use normalize_whnf before
fn as_whnf(&self) -> &Value {
match self {
- ThunkInternal::Unnormalized(_, _) => unreachable!(),
+ ThunkInternal::Unnormalized(_, _)
+ | ThunkInternal::PartialExpr(_) => unreachable!(),
ThunkInternal::Value(_, v) => v,
}
}
@@ -88,8 +100,9 @@ impl ThunkInternal {
// Always use normalize_nf before
fn as_nf(&self) -> &Value {
match self {
- ThunkInternal::Unnormalized(_, _) => unreachable!(),
- ThunkInternal::Value(WHNF, _) => unreachable!(),
+ ThunkInternal::Unnormalized(_, _)
+ | ThunkInternal::PartialExpr(_)
+ | ThunkInternal::Value(WHNF, _) => unreachable!(),
ThunkInternal::Value(NF, v) => v,
}
}
@@ -108,6 +121,10 @@ impl Thunk {
Thunk::new(NormalizationContext::new(), e.absurd())
}
+ pub(crate) fn from_partial_expr(e: ExprF<Thunk, Label, X>) -> Thunk {
+ ThunkInternal::PartialExpr(e).into_thunk()
+ }
+
// Normalizes contents to normal form; faster than `normalize_nf` if
// no one else shares this thunk
pub(crate) fn normalize_mut(&mut self) {
@@ -122,7 +139,8 @@ impl Thunk {
fn do_normalize_whnf(&self) {
let borrow = self.0.borrow();
match &*borrow {
- ThunkInternal::Unnormalized(_, _) => {
+ ThunkInternal::Unnormalized(_, _)
+ | ThunkInternal::PartialExpr(_) => {
drop(borrow);
self.0.borrow_mut().normalize_whnf();
}
@@ -135,6 +153,7 @@ impl Thunk {
let borrow = self.0.borrow();
match &*borrow {
ThunkInternal::Unnormalized(_, _)
+ | ThunkInternal::PartialExpr(_)
| ThunkInternal::Value(WHNF, _) => {
drop(borrow);
self.0.borrow_mut().normalize_nf();
@@ -249,6 +268,14 @@ impl Shift for ThunkInternal {
ThunkInternal::Unnormalized(ctx, e) => {
ThunkInternal::Unnormalized(ctx.shift(delta, var), e.clone())
}
+ ThunkInternal::PartialExpr(e) => ThunkInternal::PartialExpr(
+ e.map_ref_with_special_handling_of_binders(
+ |v| v.shift(delta, var),
+ |x, v| v.shift(delta, &var.shift(1, &x.into())),
+ X::clone,
+ Label::clone,
+ ),
+ ),
ThunkInternal::Value(m, v) => {
ThunkInternal::Value(*m, v.shift(delta, var))
}
@@ -278,6 +305,19 @@ impl Subst<Typed> for ThunkInternal {
ctx.subst_shift(var, val),
e.clone(),
),
+ ThunkInternal::PartialExpr(e) => ThunkInternal::PartialExpr(
+ e.map_ref_with_special_handling_of_binders(
+ |v| v.subst_shift(var, val),
+ |x, v| {
+ v.subst_shift(
+ &var.shift(1, &x.into()),
+ &val.shift(1, &x.into()),
+ )
+ },
+ X::clone,
+ Label::clone,
+ ),
+ ),
ThunkInternal::Value(_, v) => {
// The resulting value may not stay in normal form after substitution
ThunkInternal::Value(WHNF, v.subst_shift(var, val))
diff --git a/dhall/src/phase/typecheck.rs b/dhall/src/phase/typecheck.rs
index b163af6..ecc2d85 100644
--- a/dhall/src/phase/typecheck.rs
+++ b/dhall/src/phase/typecheck.rs
@@ -341,23 +341,34 @@ enum Ret {
}
/// Type-check an expression and return the expression alongside its type if type-checking
-/// succeeded, or an error if type-checking failed
+/// succeeded, or an error if type-checking failed.
+/// Some normalization is done while typechecking, so the returned expression might be partially
+/// normalized as well.
fn type_with(
ctx: &TypecheckContext,
e: SubExpr<Span, Normalized>,
) -> Result<Typed, TypeError> {
use dhall_syntax::ExprF::{
- Annot, App, Embed, Lam, Let, OldOptionalLit, Pi, SomeLit,
+ Annot, App, Embed, Lam, Let, OldOptionalLit, Pi, SomeLit, Var,
};
use Ret::*;
- let ret = match e.as_ref() {
+ Ok(match e.as_ref() {
Lam(x, t, b) => {
let tx = mktype(ctx, t.clone())?;
let ctx2 = ctx.insert_type(x, tx.clone());
let b = type_with(&ctx2, b.clone())?;
+ let v = Value::Lam(
+ x.clone().into(),
+ TypeThunk::from_type(tx.clone()),
+ b.to_thunk(),
+ );
let tb = b.get_type()?.into_owned();
- Ok(RetTypeIntermediate(TypeIntermediate::Pi(x.clone(), tx, tb)))
+ let ti = TypeIntermediate::Pi(x.clone(), tx, tb);
+ Typed::from_thunk_and_type(
+ Thunk::from_value(v),
+ ti.typecheck(ctx)?.to_type(),
+ )
}
Pi(x, ta, tb) => {
let ta = mktype(ctx, ta.clone())?;
@@ -390,24 +401,44 @@ fn type_with(
let e = e.rewrap(Annot(x, t));
return type_with(ctx, e);
}
- Embed(p) => Ok(RetTyped(p.clone().into())),
- _ => type_last_layer(
- ctx,
+ Embed(p) => p.clone().into(),
+ Var(var) => match ctx.lookup(&var) {
+ Some(typed) => typed,
+ None => {
+ return Err(TypeError::new(
+ ctx,
+ TypeMessage::UnboundVariable(var.clone()),
+ ))
+ }
+ },
+ _ => {
// Typecheck recursively all subexpressions
- e.as_ref()
- .traverse_ref_simple(|e| Ok(type_with(ctx, e.clone())?))?,
- ),
- }?;
- Ok(match ret {
- RetType(typ) => Typed::from_thunk_and_type(
- Thunk::new(ctx.to_normalization_ctx(), e),
- typ,
- ),
- RetTypeIntermediate(ti) => Typed::from_thunk_and_type(
- Thunk::new(ctx.to_normalization_ctx(), e),
- ti.typecheck(ctx)?.to_type(),
- ),
- RetTyped(tt) => tt,
+ let expr =
+ e.as_ref().traverse_ref_with_special_handling_of_binders(
+ |e| type_with(ctx, e.clone()),
+ |_, _| unreachable!(),
+ |_| unreachable!(),
+ |l| Ok(Label::clone(l)),
+ )?;
+ let ret = type_last_layer(ctx, &expr)?;
+ let ret = match ret {
+ RetTypeIntermediate(ti) => {
+ RetType(ti.typecheck(ctx)?.to_type())
+ }
+ ret => ret,
+ };
+ match ret {
+ RetTypeIntermediate(_) => unreachable!(),
+ RetType(typ) => {
+ let expr = expr.map_ref_simple(|typed| typed.to_thunk());
+ Typed::from_thunk_and_type(
+ Thunk::from_partial_expr(expr),
+ typ,
+ )
+ }
+ RetTyped(tt) => tt,
+ }
+ }
})
}
@@ -415,7 +446,7 @@ fn type_with(
/// layer.
fn type_last_layer(
ctx: &TypecheckContext,
- e: ExprF<Typed, Label, Normalized>,
+ e: &ExprF<Typed, Label, X>,
) -> Result<Ret, TypeError> {
use crate::error::TypeMessage::*;
use dhall_syntax::BinOp::*;
@@ -429,10 +460,7 @@ fn type_last_layer(
Pi(_, _, _) => unreachable!(),
Let(_, _, _, _) => unreachable!(),
Embed(_) => unreachable!(),
- Var(var) => match ctx.lookup(&var) {
- Some(e) => Ok(RetType(e.into_owned())),
- None => Err(mkerr(UnboundVariable(var.clone()))),
- },
+ Var(_) => unreachable!(),
App(f, a) => {
let tf = f.get_type()?;
let tf_internal = tf.internal_whnf();
@@ -448,7 +476,11 @@ fn type_last_layer(
_ => return Err(mkerr(NotAFunction(f.clone()))),
};
ensure_equal!(a.get_type()?, tx, {
- mkerr(TypeMismatch(f.clone(), tx.clone().to_normalized(), a))
+ mkerr(TypeMismatch(
+ f.clone(),
+ tx.clone().to_normalized(),
+ a.clone(),
+ ))
});
Ok(RetType(tb.subst_shift(&x.into(), &a)))
@@ -458,7 +490,7 @@ fn type_last_layer(
ensure_equal!(
&t,
x.get_type()?,
- mkerr(AnnotMismatch(x, t.to_normalized()))
+ mkerr(AnnotMismatch(x.clone(), t.to_normalized()))
);
Ok(RetType(x.get_type()?.into_owned()))
}
@@ -466,23 +498,23 @@ fn type_last_layer(
ensure_equal!(
x.get_type()?,
&builtin_to_type(Bool)?,
- mkerr(InvalidPredicate(x)),
+ mkerr(InvalidPredicate(x.clone())),
);
ensure_simple_type!(
y.get_type()?,
- mkerr(IfBranchMustBeTerm(true, y)),
+ mkerr(IfBranchMustBeTerm(true, y.clone())),
);
ensure_simple_type!(
z.get_type()?,
- mkerr(IfBranchMustBeTerm(false, z)),
+ mkerr(IfBranchMustBeTerm(false, z.clone())),
);
ensure_equal!(
y.get_type()?,
z.get_type()?,
- mkerr(IfBranchMismatch(y, z))
+ mkerr(IfBranchMismatch(y.clone(), z.clone()))
);
Ok(RetType(y.get_type()?.into_owned()))
@@ -492,7 +524,7 @@ fn type_last_layer(
Ok(RetTypeIntermediate(TypeIntermediate::ListType(t)))
}
NEListLit(xs) => {
- let mut iter = xs.into_iter().enumerate();
+ let mut iter = xs.iter().enumerate();
let (_, x) = iter.next().unwrap();
for (i, y) in iter {
ensure_equal!(
@@ -501,7 +533,7 @@ fn type_last_layer(
mkerr(InvalidListElement(
i,
x.get_type()?.to_normalized(),
- y
+ y.clone()
))
);
}
@@ -514,17 +546,17 @@ fn type_last_layer(
}
RecordType(kts) => {
let kts: BTreeMap<_, _> = kts
- .into_iter()
- .map(|(x, t)| Ok((x, t.to_type())))
+ .iter()
+ .map(|(x, t)| Ok((x.clone(), t.to_type())))
.collect::<Result<_, _>>()?;
Ok(RetTyped(TypeIntermediate::RecordType(kts).typecheck(ctx)?))
}
UnionType(kts) => {
let kts: BTreeMap<_, _> = kts
- .into_iter()
+ .iter()
.map(|(x, t)| {
Ok((
- x,
+ x.clone(),
match t {
None => None,
Some(t) => Some(t.to_type()),
@@ -536,24 +568,24 @@ fn type_last_layer(
}
RecordLit(kvs) => {
let kts = kvs
- .into_iter()
- .map(|(x, v)| Ok((x, v.get_type()?.into_owned())))
+ .iter()
+ .map(|(x, v)| Ok((x.clone(), v.get_type()?.into_owned())))
.collect::<Result<_, _>>()?;
Ok(RetTypeIntermediate(TypeIntermediate::RecordType(kts)))
}
UnionLit(x, v, kvs) => {
let mut kts: std::collections::BTreeMap<_, _> = kvs
- .into_iter()
+ .iter()
.map(|(x, v)| {
let t = match v {
Some(x) => Some(x.to_type()),
None => None,
};
- Ok((x, t))
+ Ok((x.clone(), t))
})
.collect::<Result<_, _>>()?;
let t = v.get_type()?.into_owned();
- kts.insert(x, Some(t));
+ kts.insert(x.clone(), Some(t));
Ok(RetTypeIntermediate(TypeIntermediate::UnionType(kts)))
}
Field(r, x) => {
@@ -562,7 +594,8 @@ fn type_last_layer(
Some(tth) => {
Ok(RetType(tth.to_type(ctx)?))
},
- None => Err(mkerr(MissingRecordField(x, r.clone()))),
+ None => Err(mkerr(MissingRecordField(x.clone(),
+ r.clone()))),
},
// TODO: branch here only when r.get_type() is a Const
_ => {
@@ -584,14 +617,14 @@ fn type_last_layer(
},
None => {
Err(mkerr(MissingUnionField(
- x,
+ x.clone(),
r.to_normalized(),
)))
},
},
_ => {
Err(mkerr(NotARecord(
- x,
+ x.clone(),
r.to_normalized()
)))
},
@@ -603,9 +636,9 @@ fn type_last_layer(
// ))),
}
}
- Const(c) => Ok(RetTyped(Typed::from_const(c))),
+ Const(c) => Ok(RetTyped(Typed::from_const(*c))),
Builtin(b) => {
- Ok(RetType(mktype(ctx, rc(type_of_builtin(b)).absurd())?))
+ Ok(RetType(mktype(ctx, rc(type_of_builtin(*b)).absurd())?))
}
BoolLit(_) => Ok(RetType(builtin_to_type(Bool)?)),
NaturalLit(_) => Ok(RetType(builtin_to_type(Natural)?)),
@@ -628,13 +661,13 @@ fn type_last_layer(
BinOp(o @ ListAppend, l, r) => {
match l.get_type()?.internal_whnf() {
Some(Value::AppliedBuiltin(List, _)) => {}
- _ => return Err(mkerr(BinOpTypeMismatch(o, l.clone()))),
+ _ => return Err(mkerr(BinOpTypeMismatch(*o, l.clone()))),
}
ensure_equal!(
l.get_type()?,
r.get_type()?,
- mkerr(BinOpTypeMismatch(o, r))
+ mkerr(BinOpTypeMismatch(*o, r.clone()))
);
Ok(RetType(l.get_type()?.into_owned()))
@@ -652,9 +685,17 @@ fn type_last_layer(
_ => return Err(mkerr(Unimplemented)),
})?;
- ensure_equal!(l.get_type()?, &t, mkerr(BinOpTypeMismatch(o, l)));
+ ensure_equal!(
+ l.get_type()?,
+ &t,
+ mkerr(BinOpTypeMismatch(*o, l.clone()))
+ );
- ensure_equal!(r.get_type()?, &t, mkerr(BinOpTypeMismatch(o, r)));
+ ensure_equal!(
+ r.get_type()?,
+ &t,
+ mkerr(BinOpTypeMismatch(*o, r.clone()))
+ );
Ok(RetType(t))
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-24 00:04:28 +0000