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-rw-r--r--dhall/src/normalize.rs185
-rw-r--r--dhall/src/typecheck.rs90
-rw-r--r--dhall_core/src/core.rs23
3 files changed, 233 insertions, 65 deletions
diff --git a/dhall/src/normalize.rs b/dhall/src/normalize.rs
index 88a55a1..dd9474d 100644
--- a/dhall/src/normalize.rs
+++ b/dhall/src/normalize.rs
@@ -25,9 +25,9 @@ impl<'a> Typed<'a> {
/// leave ill-typed sub-expressions unevaluated.
///
pub fn normalize(self) -> Normalized<'a> {
- self.normalize_whnf().normalize()
+ self.partially_normalize().normalize()
}
- pub(crate) fn normalize_whnf(self) -> PartiallyNormalized<'a> {
+ pub(crate) fn partially_normalize(self) -> PartiallyNormalized<'a> {
PartiallyNormalized(
normalize_whnf(
NormalizationContext::from_typecheck_ctx(&self.2),
@@ -61,6 +61,20 @@ impl<'a> PartiallyNormalized<'a> {
self.2,
)
}
+ pub(crate) fn subst_shift(
+ &self,
+ var: &V<Label>,
+ val: &PartiallyNormalized<'static>,
+ ) -> Self {
+ PartiallyNormalized(
+ self.0.subst_shift(var, val),
+ self.1.as_ref().map(|x| x.subst_shift(var, val)),
+ self.2,
+ )
+ }
+ pub(crate) fn into_whnf(self) -> WHNF {
+ self.0
+ }
}
fn shift_mut<N, E>(delta: isize, var: &V<Label>, in_expr: &mut SubExpr<N, E>) {
@@ -273,6 +287,18 @@ impl EnvItem {
Skip(var) => Skip(var.shift0(delta, x)),
}
}
+ pub(crate) fn subst_shift(
+ &self,
+ var: &V<Label>,
+ val: &PartiallyNormalized<'static>,
+ ) -> Self {
+ use EnvItem::*;
+ match self {
+ Expr(e) => Expr(e.subst_shift(var, val)),
+ Skip(v) if v == var => Expr(val.clone().into_whnf()),
+ Skip(v) => Skip(v.shift(-1, var)),
+ }
+ }
}
#[derive(Debug, Clone)]
@@ -298,10 +324,8 @@ impl NormalizationContext {
let V(x, n) = var;
match self.0.lookup(x, *n) {
Some(EnvItem::Expr(e)) => e.clone(),
- Some(EnvItem::Skip(newvar)) => {
- WHNF::Expr(rc(ExprF::Var(newvar.clone())))
- }
- None => WHNF::Expr(rc(ExprF::Var(var.clone()))),
+ Some(EnvItem::Skip(newvar)) => WHNF::Var(newvar.clone()),
+ None => WHNF::Var(var.clone()),
}
}
fn from_typecheck_ctx(tc_ctx: &crate::typecheck::TypecheckContext) -> Self {
@@ -321,6 +345,16 @@ impl NormalizationContext {
}
NormalizationContext(Rc::new(ctx))
}
+
+ fn subst_shift(
+ &self,
+ var: &V<Label>,
+ val: &PartiallyNormalized<'static>,
+ ) -> Self {
+ NormalizationContext(Rc::new(
+ self.0.map(|_, e| e.subst_shift(var, val)),
+ ))
+ }
}
/// A semantic value. This is partially redundant with `dhall_core::Expr`, on purpose. `Expr` should
@@ -347,6 +381,7 @@ pub(crate) enum WHNF {
NaturalSuccClosure,
Pi(Label, TypeThunk, TypeThunk),
+ Var(V<Label>),
Const(Const),
BoolLit(bool),
NaturalLit(Natural),
@@ -397,6 +432,8 @@ impl WHNF {
WHNF::ListConsClosure(n, Some(v)) => {
let v = v.normalize().normalize_to_expr();
let a = n.normalize().normalize_to_expr();
+ // Avoid accidental capture of the new `xs` variable
+ let v = shift0(1, &"xs".into(), &v);
dhall::subexpr!(λ(xs : List a) -> [ v ] # xs)
}
WHNF::NaturalSuccClosure => {
@@ -407,6 +444,7 @@ impl WHNF {
t.normalize().normalize_to_expr(),
e.normalize().normalize_to_expr(),
)),
+ WHNF::Var(v) => rc(ExprF::Var(v)),
WHNF::Const(c) => rc(ExprF::Const(c)),
WHNF::BoolLit(b) => rc(ExprF::BoolLit(b)),
WHNF::NaturalLit(n) => rc(ExprF::NaturalLit(n)),
@@ -539,6 +577,9 @@ impl WHNF {
fn shift(&mut self, delta: isize, var: &V<Label>) {
match self {
+ WHNF::Var(v) => {
+ std::mem::replace(v, v.shift(delta, var));
+ }
WHNF::NaturalSuccClosure
| WHNF::Const(_)
| WHNF::BoolLit(_)
@@ -609,6 +650,103 @@ impl WHNF {
WHNF::Expr(e) => shift_mut(delta, var, e),
}
}
+
+ pub(crate) fn subst_shift(
+ &self,
+ var: &V<Label>,
+ val: &PartiallyNormalized<'static>,
+ ) -> Self {
+ match self {
+ WHNF::Lam(x, t, (ctx, e)) => WHNF::Lam(
+ x.clone(),
+ t.subst_shift(var, val),
+ (ctx.subst_shift(var, val), e.clone()),
+ ),
+ WHNF::AppliedBuiltin(b, args) => WHNF::AppliedBuiltin(
+ *b,
+ args.iter().map(|v| v.subst_shift(var, val)).collect(),
+ ),
+ WHNF::NaturalSuccClosure => WHNF::NaturalSuccClosure,
+ WHNF::OptionalSomeClosure(tth) => {
+ WHNF::OptionalSomeClosure(tth.subst_shift(var, val))
+ }
+ WHNF::ListConsClosure(t, v) => WHNF::ListConsClosure(
+ t.subst_shift(var, val),
+ v.as_ref().map(|v| v.subst_shift(var, val)),
+ ),
+ WHNF::Pi(x, t, e) => WHNF::Pi(
+ x.clone(),
+ t.subst_shift(var, val),
+ e.subst_shift(&var.shift0(1, x), val),
+ ),
+ WHNF::Var(v) if v == var => val.clone().into_whnf(),
+ WHNF::Var(v) => WHNF::Var(v.shift(-1, var)),
+ WHNF::Const(c) => WHNF::Const(*c),
+ WHNF::BoolLit(b) => WHNF::BoolLit(*b),
+ WHNF::NaturalLit(n) => WHNF::NaturalLit(*n),
+ WHNF::IntegerLit(n) => WHNF::IntegerLit(*n),
+ WHNF::EmptyOptionalLit(tth) => {
+ WHNF::EmptyOptionalLit(tth.subst_shift(var, val))
+ }
+ WHNF::NEOptionalLit(th) => {
+ WHNF::NEOptionalLit(th.subst_shift(var, val))
+ }
+ WHNF::EmptyListLit(tth) => {
+ WHNF::EmptyListLit(tth.subst_shift(var, val))
+ }
+ WHNF::NEListLit(elts) => WHNF::NEListLit(
+ elts.iter().map(|v| v.subst_shift(var, val)).collect(),
+ ),
+ WHNF::RecordLit(kvs) => WHNF::RecordLit(
+ kvs.iter()
+ .map(|(k, v)| (k.clone(), v.subst_shift(var, val)))
+ .collect(),
+ ),
+ WHNF::RecordType(kvs) => WHNF::RecordType(
+ kvs.iter()
+ .map(|(k, v)| (k.clone(), v.subst_shift(var, val)))
+ .collect(),
+ ),
+ WHNF::UnionType(kts) => WHNF::UnionType(
+ kts.iter()
+ .map(|(k, v)| {
+ (k.clone(), v.as_ref().map(|v| v.subst_shift(var, val)))
+ })
+ .collect(),
+ ),
+ WHNF::UnionConstructor(x, kts) => WHNF::UnionConstructor(
+ x.clone(),
+ kts.iter()
+ .map(|(k, v)| {
+ (k.clone(), v.as_ref().map(|v| v.subst_shift(var, val)))
+ })
+ .collect(),
+ ),
+ WHNF::UnionLit(x, v, kts) => WHNF::UnionLit(
+ x.clone(),
+ v.subst_shift(var, val),
+ kts.iter()
+ .map(|(k, v)| {
+ (k.clone(), v.as_ref().map(|v| v.subst_shift(var, val)))
+ })
+ .collect(),
+ ),
+ WHNF::TextLit(elts) => WHNF::TextLit(
+ elts.iter()
+ .map(|contents| {
+ use InterpolatedTextContents::{Expr, Text};
+ match contents {
+ Expr(th) => Expr(th.subst_shift(var, val)),
+ Text(s) => Text(s.clone()),
+ }
+ })
+ .collect(),
+ ),
+ WHNF::Expr(e) => WHNF::Expr(
+ e.subst_shift(var, &val.clone().normalize().as_expr()),
+ ),
+ }
+ }
}
/// Contains either a (partially) normalized value or a
@@ -641,6 +779,21 @@ impl Thunk {
Thunk::Unnormalized(_, e) => shift_mut(delta, var, e),
}
}
+
+ pub(crate) fn subst_shift(
+ &self,
+ var: &V<Label>,
+ val: &PartiallyNormalized<'static>,
+ ) -> Self {
+ match self {
+ Thunk::Normalized(v) => {
+ Thunk::Normalized(Box::new(v.subst_shift(var, val)))
+ }
+ Thunk::Unnormalized(ctx, e) => {
+ Thunk::Unnormalized(ctx.subst_shift(var, val), e.clone())
+ }
+ }
+ }
}
/// A thunk in type position.
@@ -667,14 +820,11 @@ impl TypeThunk {
TypeThunk::from_thunk(Thunk::from_whnf(v))
}
- fn normalize(self) -> WHNF {
+ pub(crate) fn normalize(self) -> WHNF {
match self {
TypeThunk::Thunk(th) => th.normalize(),
- // TODO: let's hope for the best with the unwraps
- TypeThunk::Type(t) => normalize_whnf(
- NormalizationContext::new(),
- t.into_normalized().unwrap().0.embed_absurd(),
- ),
+ // TODO: let's hope for the best with the unwrap
+ TypeThunk::Type(t) => t.partially_normalize().unwrap().into_whnf(),
}
}
@@ -687,6 +837,17 @@ impl TypeThunk {
}
}
}
+
+ pub(crate) fn subst_shift(
+ &self,
+ var: &V<Label>,
+ val: &PartiallyNormalized<'static>,
+ ) -> Self {
+ match self {
+ TypeThunk::Thunk(th) => TypeThunk::Thunk(th.subst_shift(var, val)),
+ TypeThunk::Type(t) => TypeThunk::Type(t.subst_shift(var, val)),
+ }
+ }
}
/// Reduces the imput expression to WHNF. See doc on `WHNF` for details.
diff --git a/dhall/src/typecheck.rs b/dhall/src/typecheck.rs
index e04bf0d..8fbebf0 100644
--- a/dhall/src/typecheck.rs
+++ b/dhall/src/typecheck.rs
@@ -108,6 +108,11 @@ impl<'a> Type<'a> {
fn normalize_whnf(self) -> Result<WHNF, TypeError> {
self.0.normalize_whnf()
}
+ pub(crate) fn partially_normalize(
+ self,
+ ) -> Result<PartiallyNormalized<'a>, TypeError> {
+ self.0.partially_normalize()
+ }
fn internal(&self) -> &TypeInternal<'a> {
&self.0
}
@@ -120,37 +125,12 @@ impl<'a> Type<'a> {
pub(crate) fn shift(&self, delta: isize, var: &V<Label>) -> Self {
Type(self.0.shift(delta, var))
}
- fn subst(
- self,
- ctx: &TypecheckContext,
- x: &Label,
- val: Normalized<'static>,
- ) -> Result<Self, TypeError> {
- let tval = val.get_type()?.into_owned();
- let ctx_type = ctx.insert_type(x, tval);
- let ctx_val = ctx.insert_value(x, val);
-
- let pnzed = match self.0 {
- TypeInternal::PNzed(e) => e,
- internal => return Ok(Type(internal)),
- };
- let nzed = pnzed.normalize();
- let pnzed = Typed(nzed.0.embed_absurd(), nzed.1, ctx_val, nzed.2)
- .normalize_whnf();
-
- Ok(match &pnzed.0 {
- WHNF::Expr(e) => {
- let e = e.clone();
- match e.as_ref() {
- ExprF::Pi(_, _, _) | ExprF::RecordType(_) => {
- type_with(&ctx_type, e.embed_absurd())?
- .normalize_to_type()
- }
- _ => pnzed.normalize_to_type(),
- }
- }
- _ => pnzed.normalize_to_type(),
- })
+ pub(crate) fn subst_shift(
+ &self,
+ var: &V<Label>,
+ val: &PartiallyNormalized<'static>,
+ ) -> Self {
+ Type(self.0.subst_shift(var, val))
}
fn const_sort() -> Self {
@@ -198,9 +178,15 @@ pub(crate) enum TypeInternal<'a> {
impl<'a> TypeInternal<'a> {
pub(crate) fn into_normalized(self) -> Result<Normalized<'a>, TypeError> {
+ Ok(self.partially_normalize()?.normalize())
+ }
+ fn normalize_whnf(self) -> Result<WHNF, TypeError> {
+ Ok(self.partially_normalize()?.into_whnf())
+ }
+ fn partially_normalize(self) -> Result<PartiallyNormalized<'a>, TypeError> {
Ok(match self {
- TypeInternal::PNzed(e) => e.normalize(),
- TypeInternal::Const(c) => const_to_normalized(c),
+ TypeInternal::PNzed(e) => *e,
+ TypeInternal::Const(c) => const_to_pnormalized(c),
TypeInternal::SuperType => {
return Err(TypeError::new(
&TypecheckContext::new(),
@@ -210,10 +196,6 @@ impl<'a> TypeInternal<'a> {
}
})
}
- fn normalize_whnf(self) -> Result<WHNF, TypeError> {
- let typed: Typed = self.into_normalized()?.into();
- Ok(typed.normalize_whnf().0)
- }
fn whnf(&self) -> Option<&WHNF> {
match self {
TypeInternal::PNzed(e) => Some(&e.0),
@@ -231,6 +213,18 @@ impl<'a> TypeInternal<'a> {
SuperType => SuperType,
}
}
+ fn subst_shift(
+ &self,
+ var: &V<Label>,
+ val: &PartiallyNormalized<'static>,
+ ) -> Self {
+ use TypeInternal::*;
+ match self {
+ PNzed(e) => PNzed(Box::new(e.subst_shift(var, val))),
+ Const(c) => Const(*c),
+ SuperType => SuperType,
+ }
+ }
}
impl<'a> Eq for TypeInternal<'a> {}
@@ -260,7 +254,9 @@ impl TypedOrType {
}
fn normalize_to_type(self) -> Type<'static> {
match self {
- TypedOrType::Typed(e) => e.normalize_whnf().normalize_to_type(),
+ TypedOrType::Typed(e) => {
+ e.partially_normalize().normalize_to_type()
+ }
TypedOrType::Type(t) => t,
}
}
@@ -276,10 +272,12 @@ impl TypedOrType {
TypedOrType::Type(t) => Ok(t.get_type()?.into_owned()),
}
}
- fn normalize(self) -> Result<Normalized<'static>, TypeError> {
+ fn partially_normalize(
+ self,
+ ) -> Result<PartiallyNormalized<'static>, TypeError> {
match self {
- TypedOrType::Typed(e) => Ok(e.normalize()),
- TypedOrType::Type(t) => Ok(t.into_normalized()?),
+ TypedOrType::Typed(e) => Ok(e.partially_normalize()),
+ TypedOrType::Type(t) => Ok(t.partially_normalize()?),
}
}
}
@@ -443,8 +441,8 @@ where
}
}
-fn const_to_normalized<'a>(c: Const) -> Normalized<'a> {
- Normalized(rc(ExprF::Const(c)), Some(type_of_const(c)), PhantomData)
+fn const_to_pnormalized<'a>(c: Const) -> PartiallyNormalized<'a> {
+ PartiallyNormalized(WHNF::Const(c), Some(type_of_const(c)), PhantomData)
}
fn const_to_type<'a>(c: Const) -> Type<'a> {
@@ -897,7 +895,9 @@ fn type_last_layer(
mkerr(TypeMismatch(f.clone(), tx.clone().into_normalized()?, a))
});
- Ok(RetType(tb.clone().subst(&ctx, x, a.normalize()?)?))
+ Ok(RetType(
+ tb.subst_shift(&V(x.clone(), 0), &a.partially_normalize()?),
+ ))
}
Annot(x, t) => {
let t = t.normalize_to_type();
@@ -1147,9 +1147,9 @@ pub(crate) enum TypeMessage<'a> {
/// A structured type error that includes context
#[derive(Debug)]
pub struct TypeError {
+ type_message: TypeMessage<'static>,
context: TypecheckContext,
current: SubExpr<X, Normalized<'static>>,
- type_message: TypeMessage<'static>,
}
impl TypeError {
diff --git a/dhall_core/src/core.rs b/dhall_core/src/core.rs
index 72b42f8..a20f6d1 100644
--- a/dhall_core/src/core.rs
+++ b/dhall_core/src/core.rs
@@ -433,6 +433,17 @@ impl<N, E> SubExpr<N, E> {
{
rc(self.as_ref().visit(&mut visitor::UnNoteVisitor))
}
+
+ pub fn subst_shift(&self, var: &V<Label>, val: &Self) -> Self {
+ match self.as_ref() {
+ ExprF::Var(v) if v == var => val.clone(),
+ ExprF::Var(v) => rc(ExprF::Var(v.shift(-1, var))),
+ _ => self.map_subexprs_with_special_handling_of_binders(
+ |e| e.subst_shift(var, val),
+ |x: &Label, e| e.subst_shift(&var.shift0(1, x), val),
+ ),
+ }
+ }
}
impl<N: Clone> SubExpr<N, X> {
@@ -499,15 +510,11 @@ pub fn shift<N, E>(
var: &V<Label>,
in_expr: &SubExpr<N, E>,
) -> SubExpr<N, E> {
- use crate::ExprF::*;
match in_expr.as_ref() {
- Var(v) => rc(Var(v.shift(delta, var))),
+ ExprF::Var(v) => rc(ExprF::Var(v.shift(delta, var))),
_ => in_expr.map_subexprs_with_special_handling_of_binders(
|e| shift(delta, var, e),
- |l: &Label, e| {
- let newvar = var.shift0(1, l);
- shift(delta, &newvar, e)
- },
+ |x: &Label, e| shift(delta, &var.shift0(1, x), e),
),
}
}
@@ -540,8 +547,8 @@ fn shift0_multiple_inner<N, E>(
}
_ => in_expr.map_subexprs_with_special_handling_of_binders(
|e| shift0_multiple_inner(ctx, deltas, e),
- |l: &Label, e| {
- shift0_multiple_inner(&ctx.insert(l.clone(), ()), deltas, e)
+ |x: &Label, e| {
+ shift0_multiple_inner(&ctx.insert(x.clone(), ()), deltas, e)
},
),
}