Rename ValueF to ValueKind

1 files changed, 333 insertions, 0 deletions

diff --git a/dhall/src/semantics/core/value_kind.rs b/dhall/src/semantics/core/value_kind.rs
new file mode 100644
index 0000000..36ba068
--- /dev/null
+++ b/dhall/src/semantics/core/value_kind.rs
@@ -0,0 +1,333 @@
+use std::collections::HashMap;
+
+use crate::semantics::core::value::{ToExprOptions, Value};
+use crate::semantics::core::var::{AlphaLabel, AlphaVar, Shift, Subst};
+use crate::semantics::phase::typecheck::rc;
+use crate::semantics::phase::{Normalized, NormalizedExpr};
+use crate::syntax;
+use crate::syntax::{
+    Builtin, Const, ExprF, Integer, InterpolatedTextContents, Label,
+    NaiveDouble, Natural,
+};
+
+/// A semantic value. Subexpressions are Values, which are partially evaluated expressions that are
+/// normalized on-demand.
+/// If you compare for equality two `ValueKind`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(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(ExprF<Value, Normalized>),
+}
+
+impl ValueKind {
+    pub(crate) fn into_value_with_type(self, t: Value) -> Value {
+        Value::from_kind_and_type(self, t)
+    }
+
+    pub(crate) fn to_expr(&self, opts: ToExprOptions) -> NormalizedExpr {
+        match self {
+            ValueKind::Lam(x, t, e) => rc(ExprF::Lam(
+                x.to_label_maybe_alpha(opts.alpha),
+                t.to_expr(opts),
+                e.to_expr(opts),
+            )),
+            ValueKind::AppliedBuiltin(b, args) => args
+                .iter()
+                .map(|v| v.to_expr(opts))
+                .fold(rc(ExprF::Builtin(*b)), |acc, v| rc(ExprF::App(acc, v))),
+            ValueKind::Pi(x, t, e) => rc(ExprF::Pi(
+                x.to_label_maybe_alpha(opts.alpha),
+                t.to_expr(opts),
+                e.to_expr(opts),
+            )),
+            ValueKind::Var(v) => rc(ExprF::Var(v.to_var(opts.alpha))),
+            ValueKind::Const(c) => rc(ExprF::Const(*c)),
+            ValueKind::BoolLit(b) => rc(ExprF::BoolLit(*b)),
+            ValueKind::NaturalLit(n) => rc(ExprF::NaturalLit(*n)),
+            ValueKind::IntegerLit(n) => rc(ExprF::IntegerLit(*n)),
+            ValueKind::DoubleLit(n) => rc(ExprF::DoubleLit(*n)),
+            ValueKind::EmptyOptionalLit(n) => rc(ExprF::App(
+                rc(ExprF::Builtin(Builtin::OptionalNone)),
+                n.to_expr(opts),
+            )),
+            ValueKind::NEOptionalLit(n) => rc(ExprF::SomeLit(n.to_expr(opts))),
+            ValueKind::EmptyListLit(n) => rc(ExprF::EmptyListLit(rc(
+                ExprF::App(rc(ExprF::Builtin(Builtin::List)), n.to_expr(opts)),
+            ))),
+            ValueKind::NEListLit(elts) => rc(ExprF::NEListLit(
+                elts.iter().map(|n| n.to_expr(opts)).collect(),
+            )),
+            ValueKind::RecordLit(kvs) => rc(ExprF::RecordLit(
+                kvs.iter()
+                    .map(|(k, v)| (k.clone(), v.to_expr(opts)))
+                    .collect(),
+            )),
+            ValueKind::RecordType(kts) => rc(ExprF::RecordType(
+                kts.iter()
+                    .map(|(k, v)| (k.clone(), v.to_expr(opts)))
+                    .collect(),
+            )),
+            ValueKind::UnionType(kts) => rc(ExprF::UnionType(
+                kts.iter()
+                    .map(|(k, v)| {
+                        (k.clone(), v.as_ref().map(|v| v.to_expr(opts)))
+                    })
+                    .collect(),
+            )),
+            ValueKind::UnionConstructor(l, kts) => rc(ExprF::Field(
+                ValueKind::UnionType(kts.clone()).to_expr(opts),
+                l.clone(),
+            )),
+            ValueKind::UnionLit(l, v, kts) => rc(ExprF::App(
+                ValueKind::UnionConstructor(l.clone(), kts.clone())
+                    .to_expr(opts),
+                v.to_expr(opts),
+            )),
+            ValueKind::TextLit(elts) => rc(ExprF::TextLit(
+                elts.iter()
+                    .map(|contents| contents.map_ref(|e| e.to_expr(opts)))
+                    .collect(),
+            )),
+            ValueKind::Equivalence(x, y) => rc(ExprF::BinOp(
+                syntax::BinOp::Equivalence,
+                x.to_expr(opts),
+                y.to_expr(opts),
+            )),
+            ValueKind::PartialExpr(e) => rc(e.map_ref(|v| v.to_expr(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 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 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),
+            ),
+        }
+    }
+}