diff options
author | Nadrieril Feneanar | 2019-12-20 19:39:16 +0000 |
---|---|---|
committer | GitHub | 2019-12-20 19:39:16 +0000 |
commit | de0dd59204e979e29445d634a0739394110261ef (patch) | |
tree | a75ce010c7ea771a03cb51cc2b828dad6ea1a9f7 /dhall/src/semantics/core/value.rs | |
parent | 91ef0cf697d56c91a8d15937aa4669dc221cd6c1 (diff) | |
parent | 64cca1837cc97b7679c4e2ffd54a22ad50f05cfd (diff) |
Merge pull request #118 from Nadrieril/clarify-types
Clarify naming and file organization
Diffstat (limited to 'dhall/src/semantics/core/value.rs')
-rw-r--r-- | dhall/src/semantics/core/value.rs | 497 |
1 files changed, 374 insertions, 123 deletions
diff --git a/dhall/src/semantics/core/value.rs b/dhall/src/semantics/core/value.rs index 6e6739f..ca7c4bc 100644 --- a/dhall/src/semantics/core/value.rs +++ b/dhall/src/semantics/core/value.rs @@ -1,125 +1,93 @@ use std::cell::{Ref, RefCell, RefMut}; +use std::collections::HashMap; use std::rc::Rc; +use crate::error::{TypeError, TypeMessage}; use crate::semantics::core::context::TypecheckContext; -use crate::semantics::core::valuef::ValueF; -use crate::semantics::core::var::{AlphaVar, Shift, Subst}; -use crate::semantics::error::{TypeError, TypeMessage}; +use crate::semantics::core::var::{AlphaLabel, AlphaVar, Shift, Subst}; use crate::semantics::phase::normalize::{apply_any, normalize_whnf}; use crate::semantics::phase::typecheck::{builtin_to_value, const_to_value}; -use crate::semantics::phase::{NormalizedExpr, Typed}; -use crate::syntax::{Builtin, Const, Span}; +use crate::semantics::phase::{Normalized, NormalizedExpr, Typed}; +use crate::semantics::to_expr; +use crate::syntax::{ + Builtin, Const, ExprKind, Integer, InterpolatedTextContents, Label, + NaiveDouble, Natural, Span, +}; -#[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}; +use self::Form::{Unevaled, NF, WHNF}; + +/// 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. +/// If you compare for equality two `Value`s in WHNF, then equality will be up to alpha-equivalence +/// (renaming of bound variables) and beta-equivalence (normalization). It will recursively +/// normalize as needed. +#[derive(Clone)] +pub(crate) struct Value(Rc<RefCell<ValueInternal>>); -/// 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, + kind: ValueKind, /// This is None if and only if `value` is `Sort` (which doesn't have a type) ty: Option<Value>, span: Span, } -/// 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, +#[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 ValueKind is the first + /// constructor of the final Normal Form (NF). + WHNF, + /// Normal Form, i.e. completely normalized. + /// When all the Values in a ValueKind are at least in WHNF, and recursively so, then the + /// ValueKind 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, } -impl ValueInternal { - fn into_value(self) -> Value { - Value(Rc::new(RefCell::new(self))) - } - fn as_valuef(&self) -> &ValueF { - &self.value - } - - 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, - span: Span::Artificial, - }, - |vint| match (&vint.form, &vint.ty) { - (Unevaled, Some(ty)) => ValueInternal { - form: WHNF, - value: normalize_whnf(vint.value, &ty), - ty: vint.ty, - span: vint.span, - }, - // `value` is `Sort` - (Unevaled, None) => ValueInternal { - form: NF, - value: ValueF::Const(Const::Sort), - ty: None, - span: vint.span, - }, - // 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 => {} - } - } +#[derive(Debug, Clone, PartialEq, Eq)] +pub(crate) enum ValueKind { + /// Closures + Lam(AlphaLabel, Value, Value), + Pi(AlphaLabel, Value, Value), + // Invariant: in whnf, the evaluation must not be able to progress further. + AppliedBuiltin(Builtin, Vec<Value>), - fn get_type(&self) -> Result<&Value, TypeError> { - match &self.ty { - Some(t) => Ok(t), - None => { - Err(TypeError::new(&TypecheckContext::new(), TypeMessage::Sort)) - } - } - } + Var(AlphaVar), + Const(Const), + BoolLit(bool), + NaturalLit(Natural), + IntegerLit(Integer), + DoubleLit(NaiveDouble), + EmptyOptionalLit(Value), + NEOptionalLit(Value), + // EmptyListLit(t) means `[] : List t`, not `[] : t` + EmptyListLit(Value), + NEListLit(Vec<Value>), + RecordType(HashMap<Label, Value>), + RecordLit(HashMap<Label, Value>), + UnionType(HashMap<Label, Option<Value>>), + UnionConstructor(Label, HashMap<Label, Option<Value>>), + UnionLit(Label, Value, HashMap<Label, Option<Value>>), + // Invariant: in whnf, this must not contain interpolations that are themselves TextLits, and + // contiguous text values must be merged. + TextLit(Vec<InterpolatedTextContents<Value>>), + Equivalence(Value, Value), + // Invariant: in whnf, this must not contain a value captured by one of the variants above. + PartialExpr(ExprKind<Value, Normalized>), } impl Value { - fn new(value: ValueF, form: Form, ty: Value, span: Span) -> Value { + fn new(kind: ValueKind, form: Form, ty: Value, span: Span) -> Value { ValueInternal { form, - value, + kind, ty: Some(ty), span, } @@ -128,23 +96,23 @@ impl Value { pub(crate) fn const_sort() -> Value { ValueInternal { form: NF, - value: ValueF::Const(Const::Sort), + kind: ValueKind::Const(Const::Sort), ty: None, span: Span::Artificial, } .into_value() } - pub(crate) fn from_valuef_and_type(v: ValueF, t: Value) -> Value { + pub(crate) fn from_kind_and_type(v: ValueKind, t: Value) -> Value { Value::new(v, Unevaled, t, Span::Artificial) } - pub(crate) fn from_valuef_and_type_and_span( - v: ValueF, + pub(crate) fn from_kind_and_type_and_span( + v: ValueKind, t: Value, span: Span, ) -> Value { Value::new(v, Unevaled, t, span) } - pub(crate) fn from_valuef_and_type_whnf(v: ValueF, t: Value) -> Value { + pub(crate) fn from_kind_and_type_whnf(v: ValueKind, t: Value) -> Value { Value::new(v, WHNF, t, Span::Artificial) } pub(crate) fn from_const(c: Const) -> Self { @@ -160,7 +128,7 @@ impl Value { pub(crate) fn as_const(&self) -> Option<Const> { match &*self.as_whnf() { - ValueF::Const(c) => Some(*c), + ValueKind::Const(c) => Some(*c), _ => None, } } @@ -174,30 +142,31 @@ impl Value { 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 + /// WARNING: The returned ValueKind may be entirely unnormalized, in particular 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) + pub(crate) fn as_kind(&self) -> Ref<ValueKind> { + Ref::map(self.as_internal(), ValueInternal::as_kind) } /// 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> { + pub(crate) fn as_whnf(&self) -> Ref<ValueKind> { self.normalize_whnf(); - self.as_valuef() + self.as_kind() } - 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 { + /// Converts a value back to the corresponding AST expression. + pub(crate) fn to_expr( + &self, + opts: to_expr::ToExprOptions, + ) -> NormalizedExpr { + to_expr::value_to_expr(self, opts) + } + pub(crate) fn to_whnf_ignore_type(&self) -> ValueKind { 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 { + pub(crate) fn to_whnf_check_type(&self, ty: &Value) -> ValueKind { self.check_type(ty); self.to_whnf_ignore_type() } @@ -234,13 +203,13 @@ impl Value { pub(crate) fn app(&self, v: Value) -> Value { let body_t = match &*self.get_type_not_sort().as_whnf() { - ValueF::Pi(x, t, e) => { + ValueKind::Pi(x, t, e) => { v.check_type(t); e.subst_shift(&x.into(), &v) } _ => unreachable!("Internal type error"), }; - Value::from_valuef_and_type_whnf( + Value::from_kind_and_type_whnf( apply_any(self.clone(), v, &body_t), body_t, ) @@ -265,6 +234,156 @@ impl Value { } } +impl ValueInternal { + fn into_value(self) -> Value { + Value(Rc::new(RefCell::new(self))) + } + fn as_kind(&self) -> &ValueKind { + &self.kind + } + + fn normalize_whnf(&mut self) { + take_mut::take_or_recover( + self, + // Dummy value in case the other closure panics + || ValueInternal { + form: Unevaled, + kind: ValueKind::Const(Const::Type), + ty: None, + span: Span::Artificial, + }, + |vint| match (&vint.form, &vint.ty) { + (Unevaled, Some(ty)) => ValueInternal { + form: WHNF, + kind: normalize_whnf(vint.kind, &ty), + ty: vint.ty, + span: vint.span, + }, + // `value` is `Sort` + (Unevaled, None) => ValueInternal { + form: NF, + kind: ValueKind::Const(Const::Sort), + ty: None, + span: vint.span, + }, + // Already in WHNF + (WHNF, _) | (NF, _) => vint, + }, + ) + } + fn normalize_nf(&mut self) { + match self.form { + Unevaled => { + self.normalize_whnf(); + self.normalize_nf(); + } + WHNF => { + self.kind.normalize_mut(); + self.form = NF; + } + // Already in NF + NF => {} + } + } + + fn get_type(&self) -> Result<&Value, TypeError> { + match &self.ty { + Some(t) => Ok(t), + None => { + Err(TypeError::new(&TypecheckContext::new(), TypeMessage::Sort)) + } + } + } +} + +impl ValueKind { + pub(crate) fn into_value_with_type(self, t: Value) -> Value { + Value::from_kind_and_type(self, t) + } + + /// Converts a value back to the corresponding AST expression. + pub(crate) fn to_expr( + &self, + opts: to_expr::ToExprOptions, + ) -> NormalizedExpr { + to_expr::kind_to_expr(self, opts) + } + + pub(crate) fn normalize_mut(&mut self) { + match self { + ValueKind::Var(_) + | ValueKind::Const(_) + | ValueKind::BoolLit(_) + | ValueKind::NaturalLit(_) + | ValueKind::IntegerLit(_) + | ValueKind::DoubleLit(_) => {} + + ValueKind::EmptyOptionalLit(tth) | ValueKind::EmptyListLit(tth) => { + tth.normalize_mut(); + } + + ValueKind::NEOptionalLit(th) => { + th.normalize_mut(); + } + ValueKind::Lam(_, t, e) => { + t.normalize_mut(); + e.normalize_mut(); + } + ValueKind::Pi(_, t, e) => { + t.normalize_mut(); + e.normalize_mut(); + } + ValueKind::AppliedBuiltin(_, args) => { + for x in args.iter_mut() { + x.normalize_mut(); + } + } + ValueKind::NEListLit(elts) => { + for x in elts.iter_mut() { + x.normalize_mut(); + } + } + ValueKind::RecordLit(kvs) => { + for x in kvs.values_mut() { + x.normalize_mut(); + } + } + ValueKind::RecordType(kvs) => { + for x in kvs.values_mut() { + x.normalize_mut(); + } + } + ValueKind::UnionType(kts) | ValueKind::UnionConstructor(_, kts) => { + for x in kts.values_mut().flat_map(|opt| opt) { + x.normalize_mut(); + } + } + ValueKind::UnionLit(_, v, kts) => { + v.normalize_mut(); + for x in kts.values_mut().flat_map(|opt| opt) { + x.normalize_mut(); + } + } + ValueKind::TextLit(elts) => { + for x in elts.iter_mut() { + x.map_mut(Value::normalize_mut); + } + } + ValueKind::Equivalence(x, y) => { + x.normalize_mut(); + y.normalize_mut(); + } + ValueKind::PartialExpr(e) => { + e.map_mut(Value::normalize_mut); + } + } + } + + pub(crate) fn from_builtin(b: Builtin) -> ValueKind { + ValueKind::AppliedBuiltin(b, vec![]) + } +} + impl Shift for Value { fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> { Some(Value(self.0.shift(delta, var)?)) @@ -275,19 +394,84 @@ impl Shift for ValueInternal { fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> { Some(ValueInternal { form: self.form, - value: self.value.shift(delta, var)?, + kind: self.kind.shift(delta, var)?, ty: self.ty.shift(delta, var)?, span: self.span.clone(), }) } } +impl Shift for ValueKind { + fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> { + Some(match self { + ValueKind::Lam(x, t, e) => ValueKind::Lam( + x.clone(), + t.shift(delta, var)?, + e.shift(delta, &var.under_binder(x))?, + ), + ValueKind::AppliedBuiltin(b, args) => { + ValueKind::AppliedBuiltin(*b, args.shift(delta, var)?) + } + ValueKind::Pi(x, t, e) => ValueKind::Pi( + x.clone(), + t.shift(delta, var)?, + e.shift(delta, &var.under_binder(x))?, + ), + ValueKind::Var(v) => ValueKind::Var(v.shift(delta, var)?), + ValueKind::Const(c) => ValueKind::Const(*c), + ValueKind::BoolLit(b) => ValueKind::BoolLit(*b), + ValueKind::NaturalLit(n) => ValueKind::NaturalLit(*n), + ValueKind::IntegerLit(n) => ValueKind::IntegerLit(*n), + ValueKind::DoubleLit(n) => ValueKind::DoubleLit(*n), + ValueKind::EmptyOptionalLit(tth) => { + ValueKind::EmptyOptionalLit(tth.shift(delta, var)?) + } + ValueKind::NEOptionalLit(th) => { + ValueKind::NEOptionalLit(th.shift(delta, var)?) + } + ValueKind::EmptyListLit(tth) => { + ValueKind::EmptyListLit(tth.shift(delta, var)?) + } + ValueKind::NEListLit(elts) => { + ValueKind::NEListLit(elts.shift(delta, var)?) + } + ValueKind::RecordLit(kvs) => { + ValueKind::RecordLit(kvs.shift(delta, var)?) + } + ValueKind::RecordType(kvs) => { + ValueKind::RecordType(kvs.shift(delta, var)?) + } + ValueKind::UnionType(kts) => { + ValueKind::UnionType(kts.shift(delta, var)?) + } + ValueKind::UnionConstructor(x, kts) => { + ValueKind::UnionConstructor(x.clone(), kts.shift(delta, var)?) + } + ValueKind::UnionLit(x, v, kts) => ValueKind::UnionLit( + x.clone(), + v.shift(delta, var)?, + kts.shift(delta, var)?, + ), + ValueKind::TextLit(elts) => { + ValueKind::TextLit(elts.shift(delta, var)?) + } + ValueKind::Equivalence(x, y) => ValueKind::Equivalence( + x.shift(delta, var)?, + y.shift(delta, var)?, + ), + ValueKind::PartialExpr(e) => { + ValueKind::PartialExpr(e.shift(delta, var)?) + } + }) + } +} + impl Subst<Value> for Value { fn subst_shift(&self, var: &AlphaVar, val: &Value) -> Self { - match &*self.as_valuef() { + match &*self.as_kind() { // 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 => { + ValueKind::Var(v) if v == var => { if let Ok(self_ty) = self.get_type() { val.check_type(&self_ty.subst_shift(var, val)); } @@ -303,13 +487,80 @@ impl Subst<Value> for ValueInternal { ValueInternal { // The resulting value may not stay in wnhf after substitution form: Unevaled, - value: self.value.subst_shift(var, val), + kind: self.kind.subst_shift(var, val), ty: self.ty.subst_shift(var, val), span: self.span.clone(), } } } +impl Subst<Value> for ValueKind { + fn subst_shift(&self, var: &AlphaVar, val: &Value) -> Self { + match self { + ValueKind::AppliedBuiltin(b, args) => { + ValueKind::AppliedBuiltin(*b, args.subst_shift(var, val)) + } + ValueKind::PartialExpr(e) => { + ValueKind::PartialExpr(e.subst_shift(var, val)) + } + ValueKind::TextLit(elts) => { + ValueKind::TextLit(elts.subst_shift(var, val)) + } + ValueKind::Lam(x, t, e) => ValueKind::Lam( + x.clone(), + t.subst_shift(var, val), + e.subst_shift(&var.under_binder(x), &val.under_binder(x)), + ), + ValueKind::Pi(x, t, e) => ValueKind::Pi( + x.clone(), + t.subst_shift(var, val), + e.subst_shift(&var.under_binder(x), &val.under_binder(x)), + ), + ValueKind::Var(v) if v == var => val.to_whnf_ignore_type(), + ValueKind::Var(v) => ValueKind::Var(v.shift(-1, var).unwrap()), + ValueKind::Const(c) => ValueKind::Const(*c), + ValueKind::BoolLit(b) => ValueKind::BoolLit(*b), + ValueKind::NaturalLit(n) => ValueKind::NaturalLit(*n), + ValueKind::IntegerLit(n) => ValueKind::IntegerLit(*n), + ValueKind::DoubleLit(n) => ValueKind::DoubleLit(*n), + ValueKind::EmptyOptionalLit(tth) => { + ValueKind::EmptyOptionalLit(tth.subst_shift(var, val)) + } + ValueKind::NEOptionalLit(th) => { + ValueKind::NEOptionalLit(th.subst_shift(var, val)) + } + ValueKind::EmptyListLit(tth) => { + ValueKind::EmptyListLit(tth.subst_shift(var, val)) + } + ValueKind::NEListLit(elts) => { + ValueKind::NEListLit(elts.subst_shift(var, val)) + } + ValueKind::RecordLit(kvs) => { + ValueKind::RecordLit(kvs.subst_shift(var, val)) + } + ValueKind::RecordType(kvs) => { + ValueKind::RecordType(kvs.subst_shift(var, val)) + } + ValueKind::UnionType(kts) => { + ValueKind::UnionType(kts.subst_shift(var, val)) + } + ValueKind::UnionConstructor(x, kts) => ValueKind::UnionConstructor( + x.clone(), + kts.subst_shift(var, val), + ), + ValueKind::UnionLit(x, v, kts) => ValueKind::UnionLit( + x.clone(), + v.subst_shift(var, val), + kts.subst_shift(var, val), + ), + ValueKind::Equivalence(x, y) => ValueKind::Equivalence( + x.subst_shift(var, val), + y.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 { @@ -321,11 +572,11 @@ 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 { + if let ValueKind::Const(c) = &vint.kind { write!(fmt, "{:?}", c) } else { let mut x = fmt.debug_struct(&format!("Value@{:?}", &vint.form)); - x.field("value", &vint.value); + x.field("value", &vint.kind); if let Some(ty) = vint.ty.as_ref() { x.field("type", &ty); } else { |