diff options
Diffstat (limited to 'dhall/src/semantics/core/value.rs')
| -rw-r--r-- | dhall/src/semantics/core/value.rs | 270 |
1 files changed, 264 insertions, 6 deletions
diff --git a/dhall/src/semantics/core/value.rs b/dhall/src/semantics/core/value.rs index 1e3b965..ca7c4bc 100644 --- a/dhall/src/semantics/core/value.rs +++ b/dhall/src/semantics/core/value.rs @@ -1,21 +1,27 @@ 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::value_kind::ValueKind; -use crate::semantics::core::var::{AlphaVar, Shift, Subst}; +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::semantics::phase::{Normalized, NormalizedExpr, Typed}; use crate::semantics::to_expr; -use crate::syntax::{Builtin, Const, Span}; +use crate::syntax::{ + Builtin, Const, ExprKind, Integer, InterpolatedTextContents, Label, + NaiveDouble, Natural, Span, +}; 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. +/// 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>>); @@ -45,6 +51,38 @@ pub(crate) enum Form { 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>), + + 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(kind: ValueKind, form: Form, ty: Value, span: Span) -> Value { ValueInternal { @@ -258,6 +296,94 @@ impl ValueInternal { } } +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)?)) @@ -275,6 +401,71 @@ impl Shift for ValueInternal { } } +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_kind() { @@ -303,6 +494,73 @@ impl Subst<Value> for ValueInternal { } } +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 { |