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Diffstat (limited to 'dhall/src/semantics/nze/value.rs')
| -rw-r--r-- | dhall/src/semantics/nze/value.rs | 666 |
1 files changed, 0 insertions, 666 deletions
diff --git a/dhall/src/semantics/nze/value.rs b/dhall/src/semantics/nze/value.rs deleted file mode 100644 index 607aa0d..0000000 --- a/dhall/src/semantics/nze/value.rs +++ /dev/null @@ -1,666 +0,0 @@ -use std::collections::HashMap; -use std::rc::Rc; - -use crate::error::{TypeError, TypeMessage}; -use crate::semantics::nze::lazy; -use crate::semantics::Binder; -use crate::semantics::{ - apply_any, normalize_one_layer, normalize_tyexpr_whnf, squash_textlit, - TyEnv, -}; -use crate::semantics::{type_of_builtin, typecheck, TyExpr, TyExprKind}; -use crate::semantics::{BuiltinClosure, NzEnv, NzVar, VarEnv}; -use crate::syntax::{ - BinOp, Builtin, Const, ExprKind, Integer, InterpolatedTextContents, Label, - NaiveDouble, Natural, Span, -}; -use crate::{Normalized, NormalizedExpr, ToExprOptions}; - -/// Stores a possibly unevaluated value. Gets (partially) normalized on-demand, sharing computation -/// automatically. Uses a Rc<RefCell> to share computation. -/// If you compare for equality two `Value`s, 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<ValueInternal>); - -#[derive(Debug)] -struct ValueInternal { - kind: lazy::Lazy<Thunk, ValueKind>, - /// This is None if and only if `form` is `Sort` (which doesn't have a type) - ty: Option<Value>, - span: Span, -} - -/// An unevaluated subexpression -#[derive(Debug, Clone)] -pub(crate) enum Thunk { - /// A completely unnormalized expression. - Thunk { env: NzEnv, body: TyExpr }, - /// A partially normalized expression that may need to go through `normalize_one_layer`. - PartialExpr { - env: NzEnv, - expr: ExprKind<Value, Normalized>, - ty: Value, - }, -} - -/// An unevaluated subexpression that takes an argument. -#[derive(Debug, Clone)] -pub(crate) enum Closure { - /// Normal closure - Closure { - arg_ty: Value, - env: NzEnv, - body: TyExpr, - }, - /// Closure that ignores the argument passed - ConstantClosure { body: Value }, -} - -/// A text literal with interpolations. -// Invariant: this must not contain interpolations that are themselves TextLits, and contiguous -// text values must be merged. -#[derive(Debug, Clone, PartialEq, Eq)] -pub(crate) struct TextLit(Vec<InterpolatedTextContents<Value>>); - -/// This represents a value in Weak Head Normal Form (WHNF). This means that the value is -/// normalized up to the first constructor, but subexpressions may not be fully normalized. -/// When all the Values in a ValueKind are in WHNF, and recursively so, then the ValueKind is in -/// Normal Form (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. -/// In particular, this means that once we get a `ValueKind`, it can be considered immutable, and -/// we only need to recursively normalize its sub-`Value`s to get to the NF. -#[derive(Debug, Clone, PartialEq, Eq)] -pub(crate) enum ValueKind { - /// Closures - LamClosure { - binder: Binder, - annot: Value, - closure: Closure, - }, - PiClosure { - binder: Binder, - annot: Value, - closure: Closure, - }, - AppliedBuiltin(BuiltinClosure<Value>), - - Var(NzVar), - 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>>), - // Also keep the type of the uniontype around - UnionConstructor(Label, HashMap<Label, Option<Value>>, Value), - // Also keep the type of the uniontype and the constructor around - UnionLit(Label, Value, HashMap<Label, Option<Value>>, Value, Value), - TextLit(TextLit), - Equivalence(Value, Value), - /// Invariant: evaluation must not be able to progress with `normalize_one_layer`? - PartialExpr(ExprKind<Value, Normalized>), -} - -impl Value { - pub(crate) fn const_sort() -> Value { - ValueInternal::from_whnf( - ValueKind::Const(Const::Sort), - None, - Span::Artificial, - ) - .into_value() - } - /// Construct a Value from a completely unnormalized expression. - pub(crate) fn new_thunk(env: &NzEnv, tye: TyExpr) -> Value { - ValueInternal::from_thunk( - Thunk::new(env, tye.clone()), - tye.get_type().ok(), - tye.span().clone(), - ) - .into_value() - } - /// Construct a Value from a partially normalized expression that's not in WHNF. - pub(crate) fn from_partial_expr( - e: ExprKind<Value, Normalized>, - ty: Value, - ) -> Value { - // TODO: env - let env = NzEnv::new(); - ValueInternal::from_thunk( - Thunk::from_partial_expr(env, e, ty.clone()), - Some(ty), - Span::Artificial, - ) - .into_value() - } - /// Make a Value from a ValueKind - pub(crate) fn from_kind_and_type(v: ValueKind, t: Value) -> Value { - ValueInternal::from_whnf(v, Some(t), Span::Artificial).into_value() - } - pub(crate) fn from_const(c: Const) -> Self { - let v = ValueKind::Const(c); - match c { - Const::Type => { - Value::from_kind_and_type(v, Value::from_const(Const::Kind)) - } - Const::Kind => { - Value::from_kind_and_type(v, Value::from_const(Const::Sort)) - } - Const::Sort => Value::const_sort(), - } - } - pub(crate) fn from_builtin(b: Builtin) -> Self { - Self::from_builtin_env(b, &NzEnv::new()) - } - pub(crate) fn from_builtin_env(b: Builtin, env: &NzEnv) -> Self { - Value::from_kind_and_type( - ValueKind::from_builtin_env(b, env.clone()), - typecheck(&type_of_builtin(b)).unwrap().eval_closed_expr(), - ) - } - pub(crate) fn from_text(txt: impl ToString) -> Self { - Value::from_kind_and_type( - ValueKind::TextLit(TextLit::from_text(txt.to_string())), - Value::from_builtin(Builtin::Text), - ) - } - - pub(crate) fn as_const(&self) -> Option<Const> { - match &*self.kind() { - ValueKind::Const(c) => Some(*c), - _ => None, - } - } - // pub(crate) fn span(&self) -> Span { - // self.0.span.clone() - // } - - /// 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 kind(&self) -> &ValueKind { - self.0.kind() - } - - /// Converts a value back to the corresponding AST expression. - pub(crate) fn to_expr(&self, opts: ToExprOptions) -> NormalizedExpr { - if opts.normalize { - self.normalize(); - } - - self.to_tyexpr_noenv().to_expr(opts) - } - pub(crate) fn to_expr_tyenv(&self, env: &TyEnv) -> NormalizedExpr { - self.to_tyexpr(env.as_varenv()).to_expr_tyenv(env) - } - pub(crate) fn to_whnf_ignore_type(&self) -> ValueKind { - self.kind().clone() - } - /// Before discarding type information, check that it matches the expected return type. - pub(crate) fn to_whnf_check_type(&self, ty: &Value) -> ValueKind { - self.check_type(ty); - self.to_whnf_ignore_type() - } - - /// Normalizes contents to normal form; faster than `normalize` if - /// no one else shares this. - pub(crate) fn normalize_mut(&mut self) { - match Rc::get_mut(&mut self.0) { - // Mutate directly if sole owner - Some(vint) => vint.normalize_mut(), - // Otherwise mutate through the refcell - None => self.normalize(), - } - } - pub(crate) fn normalize(&self) { - self.0.normalize() - } - - pub(crate) fn app(&self, v: Value) -> Value { - let body_t = match &*self.get_type_not_sort().kind() { - ValueKind::PiClosure { annot, closure, .. } => { - v.check_type(annot); - closure.apply(v.clone()) - } - _ => unreachable!("Internal type error"), - }; - Value::from_kind_and_type(apply_any(self.clone(), v, &body_t), body_t) - } - - /// 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) { - // TODO: reenable - // 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.0.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") - } - - pub fn to_tyexpr(&self, venv: VarEnv) -> TyExpr { - let map_uniontype = |kts: &HashMap<Label, Option<Value>>| { - ExprKind::UnionType( - kts.iter() - .map(|(k, v)| { - (k.clone(), v.as_ref().map(|v| v.to_tyexpr(venv))) - }) - .collect(), - ) - }; - - let tye = match &*self.kind() { - ValueKind::Var(v) => TyExprKind::Var(venv.lookup(v)), - ValueKind::AppliedBuiltin(closure) => closure.to_tyexprkind(venv), - self_kind => TyExprKind::Expr(match self_kind { - ValueKind::Var(..) | ValueKind::AppliedBuiltin(..) => { - unreachable!() - } - ValueKind::LamClosure { - binder, - annot, - closure, - } => ExprKind::Lam( - binder.to_label(), - annot.to_tyexpr(venv), - closure.to_tyexpr(venv), - ), - ValueKind::PiClosure { - binder, - annot, - closure, - } => ExprKind::Pi( - binder.to_label(), - annot.to_tyexpr(venv), - closure.to_tyexpr(venv), - ), - ValueKind::Const(c) => ExprKind::Const(*c), - ValueKind::BoolLit(b) => ExprKind::BoolLit(*b), - ValueKind::NaturalLit(n) => ExprKind::NaturalLit(*n), - ValueKind::IntegerLit(n) => ExprKind::IntegerLit(*n), - ValueKind::DoubleLit(n) => ExprKind::DoubleLit(*n), - ValueKind::EmptyOptionalLit(n) => ExprKind::App( - Value::from_builtin(Builtin::OptionalNone).to_tyexpr(venv), - n.to_tyexpr(venv), - ), - ValueKind::NEOptionalLit(n) => { - ExprKind::SomeLit(n.to_tyexpr(venv)) - } - ValueKind::EmptyListLit(n) => { - ExprKind::EmptyListLit(TyExpr::new( - TyExprKind::Expr(ExprKind::App( - Value::from_builtin(Builtin::List).to_tyexpr(venv), - n.to_tyexpr(venv), - )), - Some(Value::from_const(Const::Type)), - Span::Artificial, - )) - } - ValueKind::NEListLit(elts) => ExprKind::NEListLit( - elts.iter().map(|v| v.to_tyexpr(venv)).collect(), - ), - ValueKind::TextLit(elts) => ExprKind::TextLit( - elts.iter() - .map(|t| t.map_ref(|v| v.to_tyexpr(venv))) - .collect(), - ), - ValueKind::RecordLit(kvs) => ExprKind::RecordLit( - kvs.iter() - .map(|(k, v)| (k.clone(), v.to_tyexpr(venv))) - .collect(), - ), - ValueKind::RecordType(kts) => ExprKind::RecordType( - kts.iter() - .map(|(k, v)| (k.clone(), v.to_tyexpr(venv))) - .collect(), - ), - ValueKind::UnionType(kts) => map_uniontype(kts), - ValueKind::UnionConstructor(l, kts, t) => ExprKind::Field( - TyExpr::new( - TyExprKind::Expr(map_uniontype(kts)), - Some(t.clone()), - Span::Artificial, - ), - l.clone(), - ), - ValueKind::UnionLit(l, v, kts, uniont, ctort) => ExprKind::App( - TyExpr::new( - TyExprKind::Expr(ExprKind::Field( - TyExpr::new( - TyExprKind::Expr(map_uniontype(kts)), - Some(uniont.clone()), - Span::Artificial, - ), - l.clone(), - )), - Some(ctort.clone()), - Span::Artificial, - ), - v.to_tyexpr(venv), - ), - ValueKind::Equivalence(x, y) => ExprKind::BinOp( - BinOp::Equivalence, - x.to_tyexpr(venv), - y.to_tyexpr(venv), - ), - ValueKind::PartialExpr(e) => e.map_ref(|v| v.to_tyexpr(venv)), - }), - }; - - TyExpr::new(tye, self.0.ty.clone(), self.0.span.clone()) - } - pub fn to_tyexpr_noenv(&self) -> TyExpr { - self.to_tyexpr(VarEnv::new()) - } -} - -impl ValueInternal { - fn from_whnf(k: ValueKind, ty: Option<Value>, span: Span) -> Self { - ValueInternal { - kind: lazy::Lazy::new_completed(k), - ty, - span, - } - } - fn from_thunk(th: Thunk, ty: Option<Value>, span: Span) -> Self { - ValueInternal { - kind: lazy::Lazy::new(th), - ty, - span, - } - } - fn into_value(self) -> Value { - Value(Rc::new(self)) - } - - fn kind(&self) -> &ValueKind { - &self.kind - } - fn normalize(&self) { - self.kind().normalize(); - } - // TODO: deprecated - fn normalize_mut(&mut self) { - self.normalize(); - } - - fn get_type(&self) -> Result<&Value, TypeError> { - match &self.ty { - Some(t) => Ok(t), - None => Err(TypeError::new(TypeMessage::Sort)), - } - } -} - -impl ValueKind { - pub(crate) fn into_value_with_type(self, t: Value) -> Value { - Value::from_kind_and_type(self, t) - } - - pub(crate) fn normalize(&self) { - match self { - ValueKind::Var(..) - | ValueKind::Const(_) - | ValueKind::BoolLit(_) - | ValueKind::NaturalLit(_) - | ValueKind::IntegerLit(_) - | ValueKind::DoubleLit(_) => {} - - ValueKind::EmptyOptionalLit(tth) | ValueKind::EmptyListLit(tth) => { - tth.normalize(); - } - - ValueKind::NEOptionalLit(th) => { - th.normalize(); - } - ValueKind::LamClosure { annot, closure, .. } - | ValueKind::PiClosure { annot, closure, .. } => { - annot.normalize(); - closure.normalize(); - } - ValueKind::AppliedBuiltin(closure) => closure.normalize(), - ValueKind::NEListLit(elts) => { - for x in elts.iter() { - x.normalize(); - } - } - ValueKind::RecordLit(kvs) => { - for x in kvs.values() { - x.normalize(); - } - } - ValueKind::RecordType(kvs) => { - for x in kvs.values() { - x.normalize(); - } - } - ValueKind::UnionType(kts) - | ValueKind::UnionConstructor(_, kts, _) => { - for x in kts.values().flat_map(|opt| opt) { - x.normalize(); - } - } - ValueKind::UnionLit(_, v, kts, _, _) => { - v.normalize(); - for x in kts.values().flat_map(|opt| opt) { - x.normalize(); - } - } - ValueKind::TextLit(tlit) => tlit.normalize(), - ValueKind::Equivalence(x, y) => { - x.normalize(); - y.normalize(); - } - ValueKind::PartialExpr(e) => { - e.map_ref(Value::normalize); - } - } - } - - pub(crate) fn from_builtin(b: Builtin) -> ValueKind { - ValueKind::from_builtin_env(b, NzEnv::new()) - } - pub(crate) fn from_builtin_env(b: Builtin, env: NzEnv) -> ValueKind { - ValueKind::AppliedBuiltin(BuiltinClosure::new(b, env)) - } -} - -impl Thunk { - pub fn new(env: &NzEnv, body: TyExpr) -> Self { - Thunk::Thunk { - env: env.clone(), - body, - } - } - pub fn from_partial_expr( - env: NzEnv, - expr: ExprKind<Value, Normalized>, - ty: Value, - ) -> Self { - Thunk::PartialExpr { env, expr, ty } - } - pub fn eval(self) -> ValueKind { - match self { - Thunk::Thunk { env, body } => normalize_tyexpr_whnf(&body, &env), - Thunk::PartialExpr { env, expr, ty } => { - normalize_one_layer(expr, &ty, &env) - } - } - } -} - -impl Closure { - pub fn new(arg_ty: Value, env: &NzEnv, body: TyExpr) -> Self { - Closure::Closure { - arg_ty, - env: env.clone(), - body, - } - } - /// New closure that ignores its argument - pub fn new_constant(body: Value) -> Self { - Closure::ConstantClosure { body } - } - - pub fn apply(&self, val: Value) -> Value { - match self { - Closure::Closure { env, body, .. } => { - body.eval(&env.insert_value(val)) - } - Closure::ConstantClosure { body, .. } => body.clone(), - } - } - fn apply_var(&self, var: NzVar) -> Value { - match self { - Closure::Closure { arg_ty, .. } => { - let val = Value::from_kind_and_type( - ValueKind::Var(var), - arg_ty.clone(), - ); - self.apply(val) - } - Closure::ConstantClosure { body, .. } => body.clone(), - } - } - - // TODO: somehow normalize the body. Might require to pass an env. - pub fn normalize(&self) {} - /// Convert this closure to a TyExpr - pub fn to_tyexpr(&self, venv: VarEnv) -> TyExpr { - self.apply_var(NzVar::new(venv.size())) - .to_tyexpr(venv.insert()) - } - /// If the closure variable is free in the closure, return Err. Otherwise, return the value - /// with that free variable remove. - pub fn remove_binder(&self) -> Result<Value, ()> { - match self { - Closure::Closure { .. } => { - let v = NzVar::fresh(); - // TODO: handle case where variable is used in closure - // TODO: return information about where the variable is used - Ok(self.apply_var(v)) - } - Closure::ConstantClosure { body, .. } => Ok(body.clone()), - } - } -} - -impl TextLit { - pub fn new( - elts: impl Iterator<Item = InterpolatedTextContents<Value>>, - ) -> Self { - TextLit(squash_textlit(elts)) - } - pub fn interpolate(v: Value) -> TextLit { - TextLit(vec![InterpolatedTextContents::Expr(v)]) - } - pub fn from_text(s: String) -> TextLit { - TextLit(vec![InterpolatedTextContents::Text(s)]) - } - - pub fn concat(&self, other: &TextLit) -> TextLit { - TextLit::new(self.iter().chain(other.iter()).cloned()) - } - pub fn is_empty(&self) -> bool { - self.0.is_empty() - } - /// If the literal consists of only one interpolation and not text, return the interpolated - /// value. - pub fn as_single_expr(&self) -> Option<&Value> { - use InterpolatedTextContents::Expr; - if let [Expr(v)] = self.0.as_slice() { - Some(v) - } else { - None - } - } - /// If there are no interpolations, return the corresponding text value. - pub fn as_text(&self) -> Option<String> { - use InterpolatedTextContents::Text; - if self.is_empty() { - Some(String::new()) - } else if let [Text(s)] = self.0.as_slice() { - Some(s.clone()) - } else { - None - } - } - pub fn iter( - &self, - ) -> impl Iterator<Item = &InterpolatedTextContents<Value>> { - self.0.iter() - } - /// Normalize the contained values. This does not break the invariant because we have already - /// ensured that no contained values normalize to a TextLit. - pub fn normalize(&self) { - for x in self.0.iter() { - x.map_ref(Value::normalize); - } - } -} - -impl lazy::Eval<ValueKind> for Thunk { - fn eval(self) -> ValueKind { - self.eval() - } -} - -/// Compare two values for equality modulo alpha/beta-equivalence. -impl std::cmp::PartialEq for Value { - fn eq(&self, other: &Self) -> bool { - Rc::ptr_eq(&self.0, &other.0) || self.kind() == other.kind() - } -} -impl std::cmp::Eq for Value {} - -impl std::cmp::PartialEq for Thunk { - fn eq(&self, _other: &Self) -> bool { - unreachable!( - "Trying to compare thunks but we should only compare WHNFs" - ) - } -} -impl std::cmp::Eq for Thunk {} - -impl std::cmp::PartialEq for Closure { - fn eq(&self, other: &Self) -> bool { - let v = NzVar::fresh(); - self.apply_var(v) == other.apply_var(v) - } -} -impl std::cmp::Eq for Closure {} - -impl std::fmt::Debug for Value { - fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { - let vint: &ValueInternal = &self.0; - let kind = vint.kind(); - if let ValueKind::Const(c) = kind { - return write!(fmt, "{:?}", c); - } - let mut x = fmt.debug_struct(&format!("Value@WHNF")); - x.field("kind", kind); - if let Some(ty) = vint.ty.as_ref() { - x.field("type", &ty); - } else { - x.field("type", &None::<()>); - } - x.finish() - } -} |