diff options
Diffstat (limited to '')
-rw-r--r-- | dhall/src/core/value.rs | 842 |
1 files changed, 287 insertions, 555 deletions
diff --git a/dhall/src/core/value.rs b/dhall/src/core/value.rs index 0b68bf6..3cccb1d 100644 --- a/dhall/src/core/value.rs +++ b/dhall/src/core/value.rs @@ -1,595 +1,327 @@ -use std::collections::HashMap; +use std::cell::{Ref, RefCell, RefMut}; +use std::rc::Rc; -use dhall_syntax::{ - rc, Builtin, Const, ExprF, Integer, InterpolatedTextContents, Label, - NaiveDouble, Natural, X, -}; +use dhall_syntax::{Builtin, Const}; -use crate::core::thunk::{Thunk, TypeThunk}; -use crate::core::var::{AlphaLabel, AlphaVar, Shift, Subst}; -use crate::phase::normalize::{ - apply_builtin, normalize_one_layer, squash_textlit, OutputSubExpr, -}; -use crate::phase::Typed; +use crate::core::context::TypecheckContext; +use crate::core::valuef::ValueF; +use crate::core::var::{AlphaVar, Shift, Subst}; +use crate::error::{TypeError, TypeMessage}; +use crate::phase::normalize::{apply_any, normalize_whnf}; +use crate::phase::typecheck::{builtin_to_value, const_to_value}; +use crate::phase::{NormalizedExpr, Typed}; -/// A semantic value. The invariants ensure this value represents a Weak-Head -/// Normal Form (WHNF). This means that this first constructor is the first constructor of the -/// final Normal Form (NF). -/// This WHNF must be preserved by operations on `Value`s. In particular, `subst_shift` could break -/// the invariants so need to be careful to reevaluate as needed. -/// Subexpressions are Thunks, which are partially evaluated expressions that are normalized -/// on-demand. When all the Thunks in a Value are at least in WHNF, and recursively so, then the -/// Value is in NF. This is because WHNF ensures that we have the first constructor of the NF; so -/// if we have the first constructor of the NF at all levels, we actually have the NF. -/// Equality is up to alpha-equivalence (renaming of bound variables) and beta-equivalence -/// (normalization). Equality will normalize only as needed. -#[derive(Debug, Clone, PartialEq, Eq)] -pub enum Value { - /// Closures - Lam(AlphaLabel, TypeThunk, Thunk), - Pi(AlphaLabel, TypeThunk, TypeThunk), - // Invariant: the evaluation must not be able to progress further. - AppliedBuiltin(Builtin, Vec<Thunk>), - /// `λ(x: a) -> Some x` - OptionalSomeClosure(TypeThunk), - /// `λ(x : a) -> λ(xs : List a) -> [ x ] # xs` - /// `λ(xs : List a) -> [ x ] # xs` - ListConsClosure(TypeThunk, Option<Thunk>), - /// `λ(x : Natural) -> x + 1` - NaturalSuccClosure, +#[derive(Debug, Clone, Copy)] +pub(crate) enum Form { + /// No constraints; expression may not be normalized at all. + Unevaled, + /// Weak Head Normal Form, i.e. normalized up to the first constructor, but subexpressions may + /// not be normalized. This means that the first constructor of the contained ValueF is the first + /// constructor of the final Normal Form (NF). + WHNF, + /// Normal Form, i.e. completely normalized. + /// When all the Values in a ValueF are at least in WHNF, and recursively so, then the + /// ValueF is in NF. This is because WHNF ensures that we have the first constructor of the NF; so + /// if we have the first constructor of the NF at all levels, we actually have the NF. + NF, +} +use Form::{Unevaled, NF, WHNF}; - Var(AlphaVar), - Const(Const), - BoolLit(bool), - NaturalLit(Natural), - IntegerLit(Integer), - DoubleLit(NaiveDouble), - EmptyOptionalLit(TypeThunk), - NEOptionalLit(Thunk), - // EmptyListLit(t) means `[] : List t`, not `[] : t` - EmptyListLit(TypeThunk), - NEListLit(Vec<Thunk>), - RecordLit(HashMap<Label, Thunk>), - RecordType(HashMap<Label, TypeThunk>), - UnionType(HashMap<Label, Option<TypeThunk>>), - UnionConstructor(Label, HashMap<Label, Option<TypeThunk>>), - UnionLit(Label, Thunk, HashMap<Label, Option<TypeThunk>>), - // Invariant: this must not contain interpolations that are themselves TextLits, and - // contiguous text values must be merged. - TextLit(Vec<InterpolatedTextContents<Thunk>>), - Equivalence(TypeThunk, TypeThunk), - // Invariant: this must not contain a value captured by one of the variants above. - PartialExpr(ExprF<Thunk, X>), +/// Partially normalized value. +/// Invariant: if `form` is `WHNF`, `value` must be in Weak Head Normal Form +/// Invariant: if `form` is `NF`, `value` must be fully normalized +#[derive(Debug)] +struct ValueInternal { + form: Form, + value: ValueF, + /// This is None if and only if `value` is `Sort` (which doesn't have a type) + ty: Option<Value>, } -impl Value { - pub fn into_thunk(self) -> Thunk { - Thunk::from_value(self) +/// Stores a possibly unevaluated value. Gets (partially) normalized on-demand, +/// sharing computation automatically. Uses a RefCell to share computation. +/// Can optionally store a type from typechecking to preserve type information. +#[derive(Clone)] +pub(crate) struct Value(Rc<RefCell<ValueInternal>>); + +#[derive(Copy, Clone)] +/// Controls conversion from `Value` to `Expr` +pub(crate) struct ToExprOptions { + /// Whether to convert all variables to `_` + pub(crate) alpha: bool, + /// Whether to normalize before converting + pub(crate) normalize: bool, +} + +impl ValueInternal { + fn into_value(self) -> Value { + Value(Rc::new(RefCell::new(self))) + } + fn as_valuef(&self) -> &ValueF { + &self.value } - /// Convert the value to a fully normalized syntactic expression - pub fn normalize_to_expr(&self) -> OutputSubExpr { - self.normalize_to_expr_maybe_alpha(false) - } - /// Convert the value to a fully normalized syntactic expression. Also alpha-normalize - /// if alpha is `true` - pub fn normalize_to_expr_maybe_alpha(&self, alpha: bool) -> OutputSubExpr { - // Ad-hoc macro to help construct the unapplied closures - macro_rules! make_expr { - (Natural) => { rc(ExprF::Builtin(Builtin::Natural)) }; - (var($var:ident)) => { - rc(ExprF::Var(dhall_syntax::V(stringify!($var).into(), 0))) - }; - ($var:ident) => { $var }; - (List $($rest:tt)*) => { - rc(ExprF::App( - rc(ExprF::Builtin(Builtin::List)), - make_expr!($($rest)*) - )) - }; - (Some $($rest:tt)*) => { - rc(ExprF::SomeLit( - make_expr!($($rest)*) - )) - }; - (1 + $($rest:tt)*) => { - rc(ExprF::BinOp( - dhall_syntax::BinOp::NaturalPlus, - rc(ExprF::NaturalLit(1)), - make_expr!($($rest)*) - )) - }; - ([ $($head:tt)* ] # $($tail:tt)*) => { - rc(ExprF::BinOp( - dhall_syntax::BinOp::ListAppend, - rc(ExprF::NEListLit(vec![make_expr!($($head)*)])), - make_expr!($($tail)*) - )) - }; - (λ($var:ident : $($ty:tt)*) -> $($rest:tt)*) => { - rc(ExprF::Pi( - stringify!($var).into(), - make_expr!($($ty)*), - make_expr!($($rest)*) - )) - }; + fn normalize_whnf(&mut self) { + take_mut::take_or_recover( + self, + // Dummy value in case the other closure panics + || ValueInternal { + form: Unevaled, + value: ValueF::Const(Const::Type), + ty: None, + }, + |vint| match (&vint.form, &vint.ty) { + (Unevaled, Some(ty)) => ValueInternal { + form: WHNF, + value: normalize_whnf(vint.value, &ty), + ty: vint.ty, + }, + // `value` is `Sort` + (Unevaled, None) => ValueInternal { + form: NF, + value: ValueF::Const(Const::Sort), + ty: None, + }, + // Already in WHNF + (WHNF, _) | (NF, _) => vint, + }, + ) + } + fn normalize_nf(&mut self) { + match self.form { + Unevaled => { + self.normalize_whnf(); + self.normalize_nf(); + } + WHNF => { + self.value.normalize_mut(); + self.form = NF; + } + // Already in NF + NF => {} } + } - match self { - Value::Lam(x, t, e) => rc(ExprF::Lam( - x.to_label_maybe_alpha(alpha), - t.normalize_to_expr_maybe_alpha(alpha), - e.normalize_to_expr_maybe_alpha(alpha), - )), - Value::AppliedBuiltin(b, args) => { - let mut e = rc(ExprF::Builtin(*b)); - for v in args { - e = rc(ExprF::App( - e, - v.normalize_to_expr_maybe_alpha(alpha), - )); - } - e - } - Value::OptionalSomeClosure(n) => { - let a = n.normalize_to_expr_maybe_alpha(alpha); - make_expr!(λ(x: a) -> Some var(x)) - } - Value::ListConsClosure(a, None) => { - // Avoid accidental capture of the new `x` variable - let a1 = a.under_binder(Label::from("x")); - let a1 = a1.normalize_to_expr_maybe_alpha(alpha); - let a = a.normalize_to_expr_maybe_alpha(alpha); - make_expr!(λ(x : a) -> λ(xs : List a1) -> [ var(x) ] # var(xs)) - } - Value::ListConsClosure(n, Some(v)) => { - // Avoid accidental capture of the new `xs` variable - let v = v.under_binder(Label::from("xs")); - let v = v.normalize_to_expr_maybe_alpha(alpha); - let a = n.normalize_to_expr_maybe_alpha(alpha); - make_expr!(λ(xs : List a) -> [ v ] # var(xs)) - } - Value::NaturalSuccClosure => { - make_expr!(λ(x : Natural) -> 1 + var(x)) - } - Value::Pi(x, t, e) => rc(ExprF::Pi( - x.to_label_maybe_alpha(alpha), - t.normalize_to_expr_maybe_alpha(alpha), - e.normalize_to_expr_maybe_alpha(alpha), - )), - Value::Var(v) => rc(ExprF::Var(v.to_var(alpha))), - Value::Const(c) => rc(ExprF::Const(*c)), - Value::BoolLit(b) => rc(ExprF::BoolLit(*b)), - Value::NaturalLit(n) => rc(ExprF::NaturalLit(*n)), - Value::IntegerLit(n) => rc(ExprF::IntegerLit(*n)), - Value::DoubleLit(n) => rc(ExprF::DoubleLit(*n)), - Value::EmptyOptionalLit(n) => rc(ExprF::App( - rc(ExprF::Builtin(Builtin::OptionalNone)), - n.normalize_to_expr_maybe_alpha(alpha), - )), - Value::NEOptionalLit(n) => { - rc(ExprF::SomeLit(n.normalize_to_expr_maybe_alpha(alpha))) - } - Value::EmptyListLit(n) => rc(ExprF::EmptyListLit(rc(ExprF::App( - rc(ExprF::Builtin(Builtin::List)), - n.normalize_to_expr_maybe_alpha(alpha), - )))), - Value::NEListLit(elts) => rc(ExprF::NEListLit( - elts.iter() - .map(|n| n.normalize_to_expr_maybe_alpha(alpha)) - .collect(), - )), - Value::RecordLit(kvs) => rc(ExprF::RecordLit( - kvs.iter() - .map(|(k, v)| { - (k.clone(), v.normalize_to_expr_maybe_alpha(alpha)) - }) - .collect(), - )), - Value::RecordType(kts) => rc(ExprF::RecordType( - kts.iter() - .map(|(k, v)| { - (k.clone(), v.normalize_to_expr_maybe_alpha(alpha)) - }) - .collect(), - )), - Value::UnionType(kts) => rc(ExprF::UnionType( - kts.iter() - .map(|(k, v)| { - ( - k.clone(), - v.as_ref().map(|v| { - v.normalize_to_expr_maybe_alpha(alpha) - }), - ) - }) - .collect(), - )), - Value::UnionConstructor(l, kts) => { - let kts = kts - .iter() - .map(|(k, v)| { - ( - k.clone(), - v.as_ref().map(|v| { - v.normalize_to_expr_maybe_alpha(alpha) - }), - ) - }) - .collect(); - rc(ExprF::Field(rc(ExprF::UnionType(kts)), l.clone())) - } - Value::UnionLit(l, v, kts) => rc(ExprF::App( - Value::UnionConstructor(l.clone(), kts.clone()) - .normalize_to_expr_maybe_alpha(alpha), - v.normalize_to_expr_maybe_alpha(alpha), - )), - Value::TextLit(elts) => { - use InterpolatedTextContents::{Expr, Text}; - rc(ExprF::TextLit( - elts.iter() - .map(|contents| match contents { - Expr(e) => { - Expr(e.normalize_to_expr_maybe_alpha(alpha)) - } - Text(s) => Text(s.clone()), - }) - .collect(), - )) - } - Value::Equivalence(x, y) => rc(ExprF::BinOp( - dhall_syntax::BinOp::Equivalence, - x.normalize_to_expr_maybe_alpha(alpha), - y.normalize_to_expr_maybe_alpha(alpha), - )), - Value::PartialExpr(e) => { - rc(e.map_ref_simple(|v| v.normalize_to_expr_maybe_alpha(alpha))) + fn get_type(&self) -> Result<&Value, TypeError> { + match &self.ty { + Some(t) => Ok(t), + None => { + Err(TypeError::new(&TypecheckContext::new(), TypeMessage::Sort)) } } } +} - // Deprecated - pub fn normalize(&self) -> Value { - let mut v = self.clone(); - v.normalize_mut(); - v +impl Value { + fn new(value: ValueF, form: Form, ty: Value) -> Value { + ValueInternal { + form, + value, + ty: Some(ty), + } + .into_value() + } + pub(crate) fn const_sort() -> Value { + ValueInternal { + form: NF, + value: ValueF::Const(Const::Sort), + ty: None, + } + .into_value() + } + pub(crate) fn from_valuef_and_type(v: ValueF, t: Value) -> Value { + Value::new(v, Unevaled, t) + } + pub(crate) fn from_valuef_and_type_whnf(v: ValueF, t: Value) -> Value { + Value::new(v, WHNF, t) + } + pub(crate) fn from_const(c: Const) -> Self { + const_to_value(c) + } + pub(crate) fn from_builtin(b: Builtin) -> Self { + builtin_to_value(b) } - pub fn normalize_mut(&mut self) { - match self { - Value::NaturalSuccClosure - | Value::Var(_) - | Value::Const(_) - | Value::BoolLit(_) - | Value::NaturalLit(_) - | Value::IntegerLit(_) - | Value::DoubleLit(_) => {} + pub(crate) fn as_const(&self) -> Option<Const> { + match &*self.as_whnf() { + ValueF::Const(c) => Some(*c), + _ => None, + } + } - Value::EmptyOptionalLit(tth) - | Value::OptionalSomeClosure(tth) - | Value::EmptyListLit(tth) => { - tth.normalize_mut(); - } + fn as_internal(&self) -> Ref<ValueInternal> { + self.0.borrow() + } + fn as_internal_mut(&self) -> RefMut<ValueInternal> { + self.0.borrow_mut() + } + /// WARNING: The returned ValueF may be entirely unnormalized, in aprticular it may just be an + /// unevaled PartialExpr. You probably want to use `as_whnf`. + fn as_valuef(&self) -> Ref<ValueF> { + Ref::map(self.as_internal(), ValueInternal::as_valuef) + } + /// This is what you want if you want to pattern-match on the value. + /// WARNING: drop this ref before normalizing the same value or you will run into BorrowMut + /// panics. + pub(crate) fn as_whnf(&self) -> Ref<ValueF> { + self.normalize_whnf(); + self.as_valuef() + } - Value::NEOptionalLit(th) => { - th.normalize_mut(); - } - Value::Lam(_, t, e) => { - t.normalize_mut(); - e.normalize_mut(); - } - Value::Pi(_, t, e) => { - t.normalize_mut(); - e.normalize_mut(); - } - Value::AppliedBuiltin(_, args) => { - for x in args.iter_mut() { - x.normalize_mut(); - } - } - Value::ListConsClosure(t, v) => { - t.normalize_mut(); - for x in v.iter_mut() { - x.normalize_mut(); - } - } - Value::NEListLit(elts) => { - for x in elts.iter_mut() { - x.normalize_mut(); - } - } - Value::RecordLit(kvs) => { - for x in kvs.values_mut() { - x.normalize_mut(); - } - } - Value::RecordType(kvs) => { - for x in kvs.values_mut() { - x.normalize_mut(); - } - } - Value::UnionType(kts) | Value::UnionConstructor(_, kts) => { - for x in kts.values_mut().flat_map(|opt| opt) { - x.normalize_mut(); - } - } - Value::UnionLit(_, v, kts) => { - v.normalize_mut(); - for x in kts.values_mut().flat_map(|opt| opt) { - x.normalize_mut(); - } - } - Value::TextLit(elts) => { - for x in elts.iter_mut() { - use InterpolatedTextContents::{Expr, Text}; - match x { - Expr(n) => n.normalize_mut(), - Text(_) => {} - } - } - } - Value::Equivalence(x, y) => { - x.normalize_mut(); - y.normalize_mut(); - } - Value::PartialExpr(e) => { - // TODO: need map_mut_simple - e.map_ref_simple(|v| { - v.normalize_nf(); - }); - } + pub(crate) fn to_expr(&self, opts: ToExprOptions) -> NormalizedExpr { + if opts.normalize { + self.normalize_whnf(); } + self.as_valuef().to_expr(opts) + } + pub(crate) fn to_whnf_ignore_type(&self) -> ValueF { + self.as_whnf().clone() + } + /// Before discarding type information, check that it matches the expected return type. + pub(crate) fn to_whnf_check_type(&self, ty: &Value) -> ValueF { + self.check_type(ty); + self.to_whnf_ignore_type() + } + pub(crate) fn into_typed(self) -> Typed { + Typed::from_value(self) } - /// Apply to a value - pub fn app(self, val: Value) -> Value { - self.app_val(val) + /// Mutates the contents. If no one else shares this, this avoids a RefCell lock. + fn mutate_internal(&mut self, f: impl FnOnce(&mut ValueInternal)) { + match Rc::get_mut(&mut self.0) { + // Mutate directly if sole owner + Some(refcell) => f(RefCell::get_mut(refcell)), + // Otherwise mutate through the refcell + None => f(&mut self.as_internal_mut()), + } + } + /// Normalizes contents to normal form; faster than `normalize_nf` if + /// no one else shares this. + pub(crate) fn normalize_mut(&mut self) { + self.mutate_internal(|vint| vint.normalize_nf()) } - /// Apply to a value - pub fn app_val(self, val: Value) -> Value { - self.app_thunk(val.into_thunk()) + pub(crate) fn normalize_whnf(&self) { + let borrow = self.as_internal(); + match borrow.form { + Unevaled => { + drop(borrow); + self.as_internal_mut().normalize_whnf(); + } + // Already at least in WHNF + WHNF | NF => {} + } + } + pub(crate) fn normalize_nf(&self) { + let borrow = self.as_internal(); + match borrow.form { + Unevaled | WHNF => { + drop(borrow); + self.as_internal_mut().normalize_nf(); + } + // Already in NF + NF => {} + } } - /// Apply to a thunk - pub fn app_thunk(self, th: Thunk) -> Value { - Thunk::from_value(self).app_thunk(th) + pub(crate) fn app(&self, v: Value) -> Value { + let body_t = match &*self.get_type_not_sort().as_whnf() { + ValueF::Pi(x, t, e) => { + v.check_type(t); + e.subst_shift(&x.into(), &v) + } + _ => unreachable!("Internal type error"), + }; + Value::from_valuef_and_type_whnf( + apply_any(self.clone(), v, &body_t), + body_t, + ) } - pub fn from_builtin(b: Builtin) -> Value { - Value::AppliedBuiltin(b, vec![]) + /// In debug mode, panic if the provided type doesn't match the value's type. + /// Otherwise does nothing. + pub(crate) fn check_type(&self, ty: &Value) { + debug_assert_eq!( + Some(ty), + self.get_type().ok().as_ref(), + "Internal type error" + ); + } + pub(crate) fn get_type(&self) -> Result<Value, TypeError> { + Ok(self.as_internal().get_type()?.clone()) + } + /// When we know the value isn't `Sort`, this gets the type directly + pub(crate) fn get_type_not_sort(&self) -> Value { + self.get_type() + .expect("Internal type error: value is `Sort` but shouldn't be") } } impl Shift for Value { fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> { - Some(match self { - Value::Lam(x, t, e) => Value::Lam( - x.clone(), - t.shift(delta, var)?, - e.shift(delta, &var.under_binder(x))?, - ), - Value::AppliedBuiltin(b, args) => Value::AppliedBuiltin( - *b, - args.iter() - .map(|v| Ok(v.shift(delta, var)?)) - .collect::<Result<_, _>>()?, - ), - Value::NaturalSuccClosure => Value::NaturalSuccClosure, - Value::OptionalSomeClosure(tth) => { - Value::OptionalSomeClosure(tth.shift(delta, var)?) - } - Value::ListConsClosure(t, v) => Value::ListConsClosure( - t.shift(delta, var)?, - v.as_ref().map(|v| Ok(v.shift(delta, var)?)).transpose()?, - ), - Value::Pi(x, t, e) => Value::Pi( - x.clone(), - t.shift(delta, var)?, - e.shift(delta, &var.under_binder(x))?, - ), - Value::Var(v) => Value::Var(v.shift(delta, var)?), - Value::Const(c) => Value::Const(*c), - Value::BoolLit(b) => Value::BoolLit(*b), - Value::NaturalLit(n) => Value::NaturalLit(*n), - Value::IntegerLit(n) => Value::IntegerLit(*n), - Value::DoubleLit(n) => Value::DoubleLit(*n), - Value::EmptyOptionalLit(tth) => { - Value::EmptyOptionalLit(tth.shift(delta, var)?) - } - Value::NEOptionalLit(th) => { - Value::NEOptionalLit(th.shift(delta, var)?) - } - Value::EmptyListLit(tth) => { - Value::EmptyListLit(tth.shift(delta, var)?) - } - Value::NEListLit(elts) => Value::NEListLit( - elts.iter() - .map(|v| Ok(v.shift(delta, var)?)) - .collect::<Result<_, _>>()?, - ), - Value::RecordLit(kvs) => Value::RecordLit( - kvs.iter() - .map(|(k, v)| Ok((k.clone(), v.shift(delta, var)?))) - .collect::<Result<_, _>>()?, - ), - Value::RecordType(kvs) => Value::RecordType( - kvs.iter() - .map(|(k, v)| Ok((k.clone(), v.shift(delta, var)?))) - .collect::<Result<_, _>>()?, - ), - Value::UnionType(kts) => Value::UnionType( - kts.iter() - .map(|(k, v)| { - Ok(( - k.clone(), - v.as_ref() - .map(|v| Ok(v.shift(delta, var)?)) - .transpose()?, - )) - }) - .collect::<Result<_, _>>()?, - ), - Value::UnionConstructor(x, kts) => Value::UnionConstructor( - x.clone(), - kts.iter() - .map(|(k, v)| { - Ok(( - k.clone(), - v.as_ref() - .map(|v| Ok(v.shift(delta, var)?)) - .transpose()?, - )) - }) - .collect::<Result<_, _>>()?, - ), - Value::UnionLit(x, v, kts) => Value::UnionLit( - x.clone(), - v.shift(delta, var)?, - kts.iter() - .map(|(k, v)| { - Ok(( - k.clone(), - v.as_ref() - .map(|v| Ok(v.shift(delta, var)?)) - .transpose()?, - )) - }) - .collect::<Result<_, _>>()?, - ), - Value::TextLit(elts) => Value::TextLit( - elts.iter() - .map(|contents| { - use InterpolatedTextContents::{Expr, Text}; - Ok(match contents { - Expr(th) => Expr(th.shift(delta, var)?), - Text(s) => Text(s.clone()), - }) - }) - .collect::<Result<_, _>>()?, - ), - Value::Equivalence(x, y) => { - Value::Equivalence(x.shift(delta, var)?, y.shift(delta, var)?) - } - Value::PartialExpr(e) => Value::PartialExpr( - e.traverse_ref_with_special_handling_of_binders( - |v| Ok(v.shift(delta, var)?), - |x, v| Ok(v.shift(delta, &var.under_binder(x))?), - |x| Ok(X::clone(x)), - )?, - ), + Some(Value(self.0.shift(delta, var)?)) + } +} + +impl Shift for ValueInternal { + fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> { + Some(ValueInternal { + form: self.form, + value: self.value.shift(delta, var)?, + ty: self.ty.shift(delta, var)?, }) } } -impl Subst<Typed> for Value { - fn subst_shift(&self, var: &AlphaVar, val: &Typed) -> Self { - match self { - // Retry normalizing since substituting may allow progress - Value::AppliedBuiltin(b, args) => apply_builtin( - *b, - args.iter().map(|v| v.subst_shift(var, val)).collect(), - ), - // Retry normalizing since substituting may allow progress - Value::PartialExpr(e) => { - normalize_one_layer(e.map_ref_with_special_handling_of_binders( - |v| v.subst_shift(var, val), - |x, v| { - v.subst_shift( - &var.under_binder(x), - &val.under_binder(x), - ) - }, - X::clone, - )) - } - // Retry normalizing since substituting may allow progress - Value::TextLit(elts) => { - Value::TextLit(squash_textlit(elts.iter().map(|contents| { - use InterpolatedTextContents::{Expr, Text}; - match contents { - Expr(th) => Expr(th.subst_shift(var, val)), - Text(s) => Text(s.clone()), - } - }))) - } - Value::Lam(x, t, e) => Value::Lam( - x.clone(), - t.subst_shift(var, val), - e.subst_shift(&var.under_binder(x), &val.under_binder(x)), - ), - Value::NaturalSuccClosure => Value::NaturalSuccClosure, - Value::OptionalSomeClosure(tth) => { - Value::OptionalSomeClosure(tth.subst_shift(var, val)) - } - Value::ListConsClosure(t, v) => Value::ListConsClosure( - t.subst_shift(var, val), - v.as_ref().map(|v| v.subst_shift(var, val)), - ), - Value::Pi(x, t, e) => Value::Pi( - x.clone(), - t.subst_shift(var, val), - e.subst_shift(&var.under_binder(x), &val.under_binder(x)), - ), - Value::Var(v) => match v.shift(-1, var) { - None => val.to_value().clone(), - Some(newvar) => Value::Var(newvar), - }, - Value::Const(c) => Value::Const(*c), - Value::BoolLit(b) => Value::BoolLit(*b), - Value::NaturalLit(n) => Value::NaturalLit(*n), - Value::IntegerLit(n) => Value::IntegerLit(*n), - Value::DoubleLit(n) => Value::DoubleLit(*n), - Value::EmptyOptionalLit(tth) => { - Value::EmptyOptionalLit(tth.subst_shift(var, val)) - } - Value::NEOptionalLit(th) => { - Value::NEOptionalLit(th.subst_shift(var, val)) - } - Value::EmptyListLit(tth) => { - Value::EmptyListLit(tth.subst_shift(var, val)) +impl Subst<Value> for Value { + fn subst_shift(&self, var: &AlphaVar, val: &Value) -> Self { + match &*self.as_valuef() { + // If the var matches, we can just reuse the provided value instead of copying it. + // We also check that the types match, if in debug mode. + ValueF::Var(v) if v == var => { + if let Ok(self_ty) = self.get_type() { + val.check_type(&self_ty.subst_shift(var, val)); + } + val.clone() } - Value::NEListLit(elts) => Value::NEListLit( - elts.iter().map(|v| v.subst_shift(var, val)).collect(), - ), - Value::RecordLit(kvs) => Value::RecordLit( - kvs.iter() - .map(|(k, v)| (k.clone(), v.subst_shift(var, val))) - .collect(), - ), - Value::RecordType(kvs) => Value::RecordType( - kvs.iter() - .map(|(k, v)| (k.clone(), v.subst_shift(var, val))) - .collect(), - ), - Value::UnionType(kts) => Value::UnionType( - kts.iter() - .map(|(k, v)| { - (k.clone(), v.as_ref().map(|v| v.subst_shift(var, val))) - }) - .collect(), - ), - Value::UnionConstructor(x, kts) => Value::UnionConstructor( - x.clone(), - kts.iter() - .map(|(k, v)| { - (k.clone(), v.as_ref().map(|v| v.subst_shift(var, val))) - }) - .collect(), - ), - Value::UnionLit(x, v, kts) => Value::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(), - ), - Value::Equivalence(x, y) => Value::Equivalence( - x.subst_shift(var, val), - y.subst_shift(var, val), - ), + _ => Value(self.0.subst_shift(var, val)), + } + } +} + +impl Subst<Value> for ValueInternal { + fn subst_shift(&self, var: &AlphaVar, val: &Value) -> Self { + ValueInternal { + // The resulting value may not stay in wnhf after substitution + form: Unevaled, + value: self.value.subst_shift(var, val), + ty: self.ty.subst_shift(var, val), + } + } +} + +// TODO: use Rc comparison to shortcut on identical pointers +impl std::cmp::PartialEq for Value { + fn eq(&self, other: &Self) -> bool { + *self.as_whnf() == *other.as_whnf() + } +} +impl std::cmp::Eq for Value {} + +impl std::fmt::Debug for Value { + fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { + let vint: &ValueInternal = &self.as_internal(); + if let ValueF::Const(c) = &vint.value { + write!(fmt, "{:?}", c) + } else { + let mut x = fmt.debug_struct(&format!("Value@{:?}", &vint.form)); + x.field("value", &vint.value); + if let Some(ty) = vint.ty.as_ref() { + x.field("type", &ty); + } else { + x.field("type", &None::<()>); + } + x.finish() } } } |