diff options
Diffstat (limited to 'dhall/src/semantics/core')
| -rw-r--r-- | dhall/src/semantics/core/context.rs | 1 | ||||
| -rw-r--r-- | dhall/src/semantics/core/mod.rs | 6 | ||||
| -rw-r--r-- | dhall/src/semantics/core/value.rs | 698 | ||||
| -rw-r--r-- | dhall/src/semantics/core/var.rs | 36 | ||||
| -rw-r--r-- | dhall/src/semantics/core/visitor.rs | 167 |
5 files changed, 0 insertions, 908 deletions
diff --git a/dhall/src/semantics/core/context.rs b/dhall/src/semantics/core/context.rs deleted file mode 100644 index 8b13789..0000000 --- a/dhall/src/semantics/core/context.rs +++ /dev/null @@ -1 +0,0 @@ - diff --git a/dhall/src/semantics/core/mod.rs b/dhall/src/semantics/core/mod.rs deleted file mode 100644 index 6f577f0..0000000 --- a/dhall/src/semantics/core/mod.rs +++ /dev/null @@ -1,6 +0,0 @@ -pub mod context; -pub mod value; -pub mod var; -pub mod visitor; -pub(crate) use value::*; -pub(crate) use var::*; diff --git a/dhall/src/semantics/core/value.rs b/dhall/src/semantics/core/value.rs deleted file mode 100644 index c881a9a..0000000 --- a/dhall/src/semantics/core/value.rs +++ /dev/null @@ -1,698 +0,0 @@ -use std::cell::{Ref, RefCell, RefMut}; -use std::collections::HashMap; -use std::rc::Rc; - -use crate::error::{TypeError, TypeMessage}; -use crate::semantics::core::var::Binder; -use crate::semantics::phase::normalize::{ - apply_any, normalize_tyexpr_whnf, normalize_whnf, -}; -use crate::semantics::phase::{Normalized, NormalizedExpr, ToExprOptions}; -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 self::Form::{Unevaled, 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>>); - -/// Invariant: if `form` is `WHNF`, `value` must be in Weak Head Normal Form -#[derive(Debug)] -struct ValueInternal { - form: Form, - kind: ValueKind<Value>, - /// This is None if and only if `value` is `Sort` (which doesn't have a type) - ty: Option<Value>, - span: 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 ValueKind is the first - /// constructor of the final Normal Form (NF). - /// When all the Values in a ValueKind are 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. - WHNF, -} - -/// An unevaluated subexpression -#[derive(Debug, Clone)] -pub(crate) struct Thunk { - env: NzEnv, - body: TyExpr, -} - -/// 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 { env: NzEnv, body: TyExpr }, -} - -#[derive(Debug, Clone, PartialEq, Eq)] -pub(crate) enum ValueKind<Value> { - /// Closures - LamClosure { - binder: Binder, - annot: Value, - closure: Closure, - }, - PiClosure { - binder: Binder, - annot: Value, - closure: Closure, - }, - // Invariant: in whnf, the evaluation must not be able to progress further. - 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), - // 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>), - // Invariant: absent in whnf - Thunk(Thunk), -} - -impl Value { - fn new(kind: ValueKind<Value>, form: Form, ty: Value, span: Span) -> Value { - ValueInternal { - form, - kind, - ty: Some(ty), - span, - } - .into_value() - } - pub(crate) fn const_sort() -> Value { - ValueInternal { - form: WHNF, - kind: ValueKind::Const(Const::Sort), - ty: None, - span: Span::Artificial, - } - .into_value() - } - pub(crate) fn new_thunk(env: &NzEnv, tye: TyExpr) -> Value { - ValueInternal { - form: Unevaled, - kind: ValueKind::Thunk(Thunk::new(env, tye.clone())), - ty: tye.get_type().ok(), - span: tye.span().clone(), - } - .into_value() - } - pub(crate) fn from_kind_and_type(v: ValueKind<Value>, t: Value) -> Value { - Value::new(v, Unevaled, t, Span::Artificial) - } - pub(crate) fn from_kind_and_type_whnf( - v: ValueKind<Value>, - t: Value, - ) -> Value { - Value::new(v, WHNF, t, Span::Artificial) - } - 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 as_const(&self) -> Option<Const> { - match &*self.kind() { - ValueKind::Const(c) => Some(*c), - _ => None, - } - } - pub(crate) fn span(&self) -> Span { - self.as_internal().span.clone() - } - - fn as_internal(&self) -> Ref<ValueInternal> { - self.0.borrow() - } - fn as_internal_mut(&self) -> RefMut<ValueInternal> { - self.0.borrow_mut() - } - /// 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) -> Ref<ValueKind<Value>> { - self.normalize_whnf(); - Ref::map(self.as_internal(), ValueInternal::as_kind) - } - - /// Converts a value back to the corresponding AST expression. - pub(crate) fn to_expr(&self, opts: ToExprOptions) -> NormalizedExpr { - if opts.normalize { - self.normalize_nf(); - } - - self.to_tyexpr_noenv().to_expr(opts) - } - pub(crate) fn to_whnf_ignore_type(&self) -> ValueKind<Value> { - 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<Value> { - self.check_type(ty); - self.to_whnf_ignore_type() - } - - /// 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()) - } - - pub(crate) fn normalize_whnf(&self) { - let borrow = self.as_internal(); - match borrow.form { - Unevaled => { - drop(borrow); - self.as_internal_mut().normalize_whnf(); - } - // Already in WHNF - WHNF => {} - } - } - pub(crate) fn normalize_nf(&self) { - self.as_internal_mut().normalize_nf(); - } - - 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_whnf( - 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.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") - } - - pub fn to_tyexpr(&self, venv: VarEnv) -> TyExpr { - let tye = match &*self.kind() { - ValueKind::Var(v) => TyExprKind::Var(venv.lookup(v)), - ValueKind::LamClosure { - binder, - annot, - closure, - } => TyExprKind::Expr(ExprKind::Lam( - binder.to_label(), - annot.to_tyexpr(venv), - closure.to_tyexpr(venv), - )), - ValueKind::PiClosure { - binder, - annot, - closure, - } => TyExprKind::Expr(ExprKind::Pi( - binder.to_label(), - annot.to_tyexpr(venv), - closure.to_tyexpr(venv), - )), - ValueKind::AppliedBuiltin(closure) => closure.to_tyexprkind(venv), - ValueKind::UnionConstructor(l, kts, t) => { - TyExprKind::Expr(ExprKind::Field( - TyExpr::new( - TyExprKind::Expr(ExprKind::UnionType( - kts.into_iter() - .map(|(k, v)| { - ( - k.clone(), - v.as_ref().map(|v| v.to_tyexpr(venv)), - ) - }) - .collect(), - )), - Some(t.clone()), - Span::Artificial, - ), - l.clone(), - )) - } - ValueKind::UnionLit(l, v, kts, uniont, ctort) => { - TyExprKind::Expr(ExprKind::App( - TyExpr::new( - TyExprKind::Expr(ExprKind::Field( - TyExpr::new( - TyExprKind::Expr(ExprKind::UnionType( - kts.into_iter() - .map(|(k, v)| { - ( - k.clone(), - v.as_ref() - .map(|v| v.to_tyexpr(venv)), - ) - }) - .collect(), - )), - Some(uniont.clone()), - Span::Artificial, - ), - l.clone(), - )), - Some(ctort.clone()), - Span::Artificial, - ), - v.to_tyexpr(venv), - )) - } - ValueKind::Thunk(th) => return th.to_tyexpr(venv), - self_kind => { - let self_kind = self_kind.map_ref(|v| v.to_tyexpr(venv)); - let expr = match self_kind { - ValueKind::Var(..) - | ValueKind::LamClosure { .. } - | ValueKind::PiClosure { .. } - | ValueKind::AppliedBuiltin(..) - | ValueKind::UnionConstructor(..) - | ValueKind::UnionLit(..) - | ValueKind::Thunk(..) => unreachable!(), - 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, - ), - ValueKind::NEOptionalLit(n) => ExprKind::SomeLit(n), - ValueKind::EmptyListLit(n) => { - ExprKind::EmptyListLit(TyExpr::new( - TyExprKind::Expr(ExprKind::App( - Value::from_builtin(Builtin::List) - .to_tyexpr(venv), - n, - )), - Some(Value::from_const(Const::Type)), - Span::Artificial, - )) - } - ValueKind::NEListLit(elts) => ExprKind::NEListLit(elts), - ValueKind::RecordLit(kvs) => { - ExprKind::RecordLit(kvs.into_iter().collect()) - } - ValueKind::RecordType(kts) => { - ExprKind::RecordType(kts.into_iter().collect()) - } - ValueKind::UnionType(kts) => { - ExprKind::UnionType(kts.into_iter().collect()) - } - ValueKind::TextLit(elts) => { - ExprKind::TextLit(elts.into_iter().collect()) - } - ValueKind::Equivalence(x, y) => { - ExprKind::BinOp(BinOp::Equivalence, x, y) - } - ValueKind::PartialExpr(e) => e, - }; - TyExprKind::Expr(expr) - } - }; - - let self_ty = self.as_internal().ty.clone(); - let self_span = self.as_internal().span.clone(); - TyExpr::new(tye, self_ty, self_span) - } - pub fn to_tyexpr_noenv(&self) -> TyExpr { - self.to_tyexpr(VarEnv::new()) - } -} - -impl ValueInternal { - fn into_value(self) -> Value { - Value(Rc::new(RefCell::new(self))) - } - fn as_kind(&self) -> &ValueKind<Value> { - &self.kind - } - - fn normalize_whnf(&mut self) { - let dummy = ValueInternal { - form: Unevaled, - kind: ValueKind::Const(Const::Type), - ty: None, - span: Span::Artificial, - }; - let vint = std::mem::replace(self, dummy); - *self = 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: WHNF, - kind: ValueKind::Const(Const::Sort), - ty: None, - span: vint.span, - }, - // Already in WHNF - (WHNF, _) => vint, - } - } - fn normalize_nf(&mut self) { - if let Unevaled = self.form { - self.normalize_whnf(); - } - self.kind.normalize_mut(); - } - - fn get_type(&self) -> Result<&Value, TypeError> { - match &self.ty { - Some(t) => Ok(t), - None => Err(TypeError::new(TypeMessage::Sort)), - } - } -} - -impl ValueKind<Value> { - pub(crate) fn into_value_with_type(self, t: Value) -> Value { - Value::from_kind_and_type(self, t) - } - - 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::LamClosure { annot, .. } - | ValueKind::PiClosure { annot, .. } => { - annot.normalize_mut(); - } - ValueKind::AppliedBuiltin(closure) => closure.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); - } - ValueKind::Thunk(..) => { - unreachable!("Should only normalize_mut values in WHNF") - } - } - } - - pub(crate) fn from_builtin(b: Builtin) -> ValueKind<Value> { - ValueKind::from_builtin_env(b, NzEnv::new()) - } - pub(crate) fn from_builtin_env(b: Builtin, env: NzEnv) -> ValueKind<Value> { - ValueKind::AppliedBuiltin(BuiltinClosure::new(b, env)) - } -} - -impl<V> ValueKind<V> { - fn traverse_ref_with_special_handling_of_binders<'a, V2, E>( - &'a self, - visit_val: impl FnMut(&'a V) -> Result<V2, E>, - visit_under_binder: impl for<'b> FnMut( - &'a Binder, - &'b V, - &'a V, - ) -> Result<V2, E>, - ) -> Result<ValueKind<V2>, E> { - use crate::semantics::visitor; - use visitor::ValueKindVisitor; - visitor::TraverseRefWithBindersVisitor { - visit_val, - visit_under_binder, - } - .visit(self) - } - - fn map_ref_with_special_handling_of_binders<'a, V2>( - &'a self, - mut map_val: impl FnMut(&'a V) -> V2, - mut map_under_binder: impl for<'b> FnMut(&'a Binder, &'b V, &'a V) -> V2, - ) -> ValueKind<V2> { - use crate::syntax::trivial_result; - trivial_result(self.traverse_ref_with_special_handling_of_binders( - |x| Ok(map_val(x)), - |l, t, x| Ok(map_under_binder(l, t, x)), - )) - } - - fn map_ref<'a, V2>( - &'a self, - map_val: impl Fn(&'a V) -> V2, - ) -> ValueKind<V2> { - self.map_ref_with_special_handling_of_binders(&map_val, |_, _, x| { - map_val(x) - }) - } -} - -impl Thunk { - pub fn new(env: &NzEnv, body: TyExpr) -> Self { - Thunk { - env: env.clone(), - body, - } - } - - pub fn eval(&self) -> Value { - normalize_tyexpr_whnf(&self.body, &self.env) - } - pub fn to_tyexpr(&self, venv: VarEnv) -> TyExpr { - self.eval().to_tyexpr(venv) - } -} - -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(env: &NzEnv, body: TyExpr) -> Self { - Closure::ConstantClosure { - env: env.clone(), - body, - } - } - - pub fn apply(&self, val: Value) -> Value { - match self { - Closure::Closure { env, body, .. } => { - body.eval(&env.insert_value(val)) - } - Closure::ConstantClosure { env, body, .. } => body.eval(env), - } - } - 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 { env, body, .. } => body.eval(env), - } - } - - /// 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, ()> { - let v = NzVar::fresh(); - match self { - Closure::Closure { .. } => { - // 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 { .. } => { - // Ok: the variable is indeed ignored - Ok(self.apply_var(v)) - } - } - } -} - -/// Compare two values for equality modulo alpha/beta-equivalence. -// TODO: use Rc comparison to shortcut on identical pointers -impl std::cmp::PartialEq for Value { - fn eq(&self, other: &Self) -> bool { - *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.as_internal(); - 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.kind); - if let Some(ty) = vint.ty.as_ref() { - x.field("type", &ty); - } else { - x.field("type", &None::<()>); - } - x.finish() - } - } -} diff --git a/dhall/src/semantics/core/var.rs b/dhall/src/semantics/core/var.rs deleted file mode 100644 index 264b81d..0000000 --- a/dhall/src/semantics/core/var.rs +++ /dev/null @@ -1,36 +0,0 @@ -use crate::syntax::Label; - -// Exactly like a Label, but equality returns always true. -// This is so that ValueKind equality is exactly alpha-equivalence. -#[derive(Clone, Eq)] -pub struct Binder { - name: Label, -} - -impl Binder { - pub(crate) fn new(name: Label) -> Self { - Binder { name } - } - pub(crate) fn to_label(&self) -> Label { - self.clone().into() - } -} - -/// Equality up to alpha-equivalence -impl std::cmp::PartialEq for Binder { - fn eq(&self, _other: &Self) -> bool { - true - } -} - -impl std::fmt::Debug for Binder { - fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { - write!(f, "Binder({})", &self.name) - } -} - -impl From<Binder> for Label { - fn from(x: Binder) -> Label { - x.name - } -} diff --git a/dhall/src/semantics/core/visitor.rs b/dhall/src/semantics/core/visitor.rs deleted file mode 100644 index d1a85d8..0000000 --- a/dhall/src/semantics/core/visitor.rs +++ /dev/null @@ -1,167 +0,0 @@ -use std::iter::FromIterator; - -use crate::semantics::{Binder, BuiltinClosure, ValueKind}; -use crate::syntax::Label; - -/// A visitor trait that can be used to traverse `ValueKind`s. We need this pattern so that Rust lets -/// us have as much mutability as we can. See the equivalent file in `crate::syntax` for more -/// details. -pub(crate) trait ValueKindVisitor<'a, V1, V2>: Sized { - type Error; - - fn visit_val(&mut self, val: &'a V1) -> Result<V2, Self::Error>; - fn visit_binder( - mut self, - _label: &'a Binder, - ty: &'a V1, - val: &'a V1, - ) -> Result<(V2, V2), Self::Error> { - Ok((self.visit_val(ty)?, self.visit_val(val)?)) - } - fn visit_vec(&mut self, x: &'a [V1]) -> Result<Vec<V2>, Self::Error> { - x.iter().map(|e| self.visit_val(e)).collect() - } - fn visit_opt( - &mut self, - x: &'a Option<V1>, - ) -> Result<Option<V2>, Self::Error> { - Ok(match x { - Some(x) => Some(self.visit_val(x)?), - None => None, - }) - } - fn visit_map<T>( - &mut self, - x: impl IntoIterator<Item = (&'a Label, &'a V1)>, - ) -> Result<T, Self::Error> - where - V1: 'a, - T: FromIterator<(Label, V2)>, - { - x.into_iter() - .map(|(k, x)| Ok((k.clone(), self.visit_val(x)?))) - .collect() - } - fn visit_optmap<T>( - &mut self, - x: impl IntoIterator<Item = (&'a Label, &'a Option<V1>)>, - ) -> Result<T, Self::Error> - where - V1: 'a, - T: FromIterator<(Label, Option<V2>)>, - { - x.into_iter() - .map(|(k, x)| Ok((k.clone(), self.visit_opt(x)?))) - .collect() - } - - fn visit( - self, - input: &'a ValueKind<V1>, - ) -> Result<ValueKind<V2>, Self::Error> { - visit_ref(self, input) - } -} - -fn visit_ref<'a, Visitor, V1, V2>( - mut v: Visitor, - input: &'a ValueKind<V1>, -) -> Result<ValueKind<V2>, Visitor::Error> -where - Visitor: ValueKindVisitor<'a, V1, V2>, -{ - use ValueKind::*; - Ok(match input { - LamClosure { - binder, - annot, - closure, - } => LamClosure { - binder: binder.clone(), - annot: v.visit_val(annot)?, - closure: closure.clone(), - }, - PiClosure { - binder, - annot, - closure, - } => PiClosure { - binder: binder.clone(), - annot: v.visit_val(annot)?, - closure: closure.clone(), - }, - AppliedBuiltin(BuiltinClosure { - b, - args, - types, - env, - }) => AppliedBuiltin(BuiltinClosure { - b: *b, - args: v.visit_vec(args)?, - types: v.visit_vec(types)?, - env: env.clone(), - }), - Var(v) => Var(*v), - Const(k) => Const(*k), - BoolLit(b) => BoolLit(*b), - NaturalLit(n) => NaturalLit(*n), - IntegerLit(n) => IntegerLit(*n), - DoubleLit(n) => DoubleLit(*n), - EmptyOptionalLit(t) => EmptyOptionalLit(v.visit_val(t)?), - NEOptionalLit(x) => NEOptionalLit(v.visit_val(x)?), - EmptyListLit(t) => EmptyListLit(v.visit_val(t)?), - NEListLit(xs) => NEListLit(v.visit_vec(xs)?), - RecordType(kts) => RecordType(v.visit_map(kts)?), - RecordLit(kvs) => RecordLit(v.visit_map(kvs)?), - UnionType(kts) => UnionType(v.visit_optmap(kts)?), - UnionConstructor(l, kts, uniont) => UnionConstructor( - l.clone(), - v.visit_optmap(kts)?, - v.visit_val(uniont)?, - ), - UnionLit(l, x, kts, uniont, ctort) => UnionLit( - l.clone(), - v.visit_val(x)?, - v.visit_optmap(kts)?, - v.visit_val(uniont)?, - v.visit_val(ctort)?, - ), - TextLit(ts) => TextLit( - ts.iter() - .map(|t| t.traverse_ref(|e| v.visit_val(e))) - .collect::<Result<_, _>>()?, - ), - Equivalence(x, y) => Equivalence(v.visit_val(x)?, v.visit_val(y)?), - PartialExpr(e) => PartialExpr(e.traverse_ref(|e| v.visit_val(e))?), - Thunk(th) => Thunk(th.clone()), - }) -} - -pub struct TraverseRefWithBindersVisitor<F1, F2> { - pub visit_val: F1, - pub visit_under_binder: F2, -} - -impl<'a, V1, V2, Err, F1, F2> ValueKindVisitor<'a, V1, V2> - for TraverseRefWithBindersVisitor<F1, F2> -where - V1: 'a, - F1: FnMut(&'a V1) -> Result<V2, Err>, - F2: for<'b> FnOnce(&'a Binder, &'b V1, &'a V1) -> Result<V2, Err>, -{ - type Error = Err; - - fn visit_val(&mut self, val: &'a V1) -> Result<V2, Self::Error> { - (self.visit_val)(val) - } - fn visit_binder<'b>( - mut self, - label: &'a Binder, - ty: &'a V1, - val: &'a V1, - ) -> Result<(V2, V2), Self::Error> { - let val = (self.visit_under_binder)(label, ty, val)?; - let ty = (self.visit_val)(ty)?; - Ok((ty, val)) - } -} |