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-rw-r--r--src/core.rs120
1 files changed, 46 insertions, 74 deletions
diff --git a/src/core.rs b/src/core.rs
index 39bca18..71b6b14 100644
--- a/src/core.rs
+++ b/src/core.rs
@@ -584,11 +584,7 @@ fn map_record_value<'a, I, K, V, U, F>(it: I, f: F) -> BTreeMap<K, U>
/// descend into a lambda or let expression that binds a variable of the same
/// name in order to avoid shifting the bound variables by mistake.
///
-pub fn shift<'i, S, T, A>(d: isize, v: V, e: &Expr<'i, S, A>) -> Expr<'i, T, A>
- where S: fmt::Debug,
- T: fmt::Debug,
- A: Clone + fmt::Debug,
-{
+pub fn shift<'i, S, T, A: Clone>(d: isize, v: V, e: &Expr<'i, S, A>) -> Expr<'i, T, A> {
use Expr::*;
let V(x, n) = v;
match e {
@@ -617,88 +613,64 @@ pub fn shift<'i, S, T, A>(d: isize, v: V, e: &Expr<'i, S, A>) -> Expr<'i, T, A>
let r2 = shift(d, V(x, n), r);
Let(f, mt2, bx(r2), bx(e2))
}
-/*
-shift d v (Annot a b) = Annot a' b'
- where
- a' = shift d v a
- b' = shift d v b
- */
+ &Annot(ref a, ref b) => shift_op2(Annot, d, v, a, b),
&BuiltinType(t) => BuiltinType(t),
&BuiltinValue(v) => BuiltinValue(v),
&BoolLit(a) => BoolLit(a),
- &BoolAnd(ref a, ref b) => BoolAnd(bx(shift(d, v, a)), bx(shift(d, v, b))),
-/*
-shift d v (BoolOr a b) = BoolOr a' b'
- where
- a' = shift d v a
- b' = shift d v b
-shift d v (BoolEQ a b) = BoolEQ a' b'
- where
- a' = shift d v a
- b' = shift d v b
-shift d v (BoolNE a b) = BoolNE a' b'
- where
- a' = shift d v a
- b' = shift d v b
-shift d v (BoolIf a b c) = BoolIf a' b' c'
- where
- a' = shift d v a
- b' = shift d v b
- c' = shift d v c
-*/
+ &BoolAnd(ref a, ref b) => shift_op2(BoolAnd, d, v, a, b),
+ &BoolOr(ref a, ref b) => shift_op2(BoolOr, d, v, a, b),
+ &BoolEQ(ref a, ref b) => shift_op2(BoolEQ, d, v, a, b),
+ &BoolNE(ref a, ref b) => shift_op2(BoolNE, d, v, a, b),
+ &BoolIf(ref a, ref b, ref c) => {
+ BoolIf(bx(shift(d, v, a)), bx(shift(d, v, b)), bx(shift(d, v, c)))
+ }
&NaturalLit(a) => NaturalLit(a),
&NaturalPlus(ref a, ref b) => NaturalPlus(bx(shift(d, v, a)), bx(shift(d, v, b))),
-/*
-shift d v (NaturalTimes a b) = NaturalTimes a' b'
- where
- a' = shift d v a
- b' = shift d v b
-shift _ _ (IntegerLit a) = IntegerLit a
-shift _ _ (DoubleLit a) = DoubleLit a
-shift _ _ (TextLit a) = TextLit a
-shift d v (TextAppend a b) = TextAppend a' b'
- where
- a' = shift d v a
- b' = shift d v b
-shift d v (ListLit a b) = ListLit a' b'
- where
- a' = shift d v a
- b' = fmap (shift d v) b
-shift d v (OptionalLit a b) = OptionalLit a' b'
- where
- a' = shift d v a
- b' = fmap (shift d v) b
-*/
- &Record(ref a) =>
- Record(map_record_value(a, |val| shift(d, v, val))),
- &RecordLit(ref a) =>
- RecordLit(map_record_value(a, |val| shift(d, v, val))),
- &Union(ref a) =>
- Union(map_record_value(a, |val| shift(d, v, val))),
- /*
-shift d v (UnionLit a b c) = UnionLit a b' c'
- where
- b' = shift d v b
- c' = fmap (shift d v) c
-shift d v (Combine a b) = Combine a' b'
- where
- a' = shift d v a
- b' = shift d v b
-shift d v (Merge a b c) = Merge a' b' c'
- where
- a' = shift d v a
- b' = shift d v b
- c' = shift d v c
- */
+ &NaturalTimes(ref a, ref b) => shift_op2(NaturalTimes, d, v, a, b),
+ &IntegerLit(a) => IntegerLit(a),
+ &DoubleLit(a) => DoubleLit(a),
+ &TextLit(ref a) => TextLit(a.clone()),
+ &TextAppend(ref a, ref b) => shift_op2(TextAppend, d, v, a, b),
+ &ListLit(ref t, ref es) => {
+ ListLit(bx(shift(d, v, t)),
+ es.iter().map(|e| shift(d, v, e)).collect())
+ }
+ &OptionalLit(ref t, ref es) => {
+ OptionalLit(bx(shift(d, v, t)),
+ es.iter().map(|e| shift(d, v, e)).collect())
+ }
+ &Record(ref a) => Record(map_record_value(a, |val| shift(d, v, val))),
+ &RecordLit(ref a) => RecordLit(map_record_value(a, |val| shift(d, v, val))),
+ &Union(ref a) => Union(map_record_value(a, |val| shift(d, v, val))),
+ &UnionLit(k, ref uv, ref a) => {
+ UnionLit(k,
+ bx(shift(d, v, uv)),
+ map_record_value(a, |val| shift(d, v, val)))
+ }
+ &Combine(ref a, ref b) => shift_op2(Combine, d, v, a, b),
+ &Merge(ref a, ref b, ref c) => {
+ Merge(bx(shift(d, v, a)), bx(shift(d, v, b)), bx(shift(d, v, c)))
+ }
&Field(ref a, b) => Field(bx(shift(d, v, a)), b),
&Note(_, ref b) => shift(d, v, b),
// The Dhall compiler enforces that all embedded values are closed expressions
// and `shift` does nothing to a closed expression
&Embed(ref p) => Embed(p.clone()),
- e => panic!("Unimplemented shift case: {:?}", (d, v, e)),
}
}
+fn shift_op2<'i, S, T, A, F>(f: F,
+ d: isize,
+ v: V,
+ a: &Expr<'i, S, A>,
+ b: &Expr<'i, S, A>)
+ -> Expr<'i, T, A>
+ where F: FnOnce(Box<Expr<'i, T, A>>, Box<Expr<'i, T, A>>) -> Expr<'i, T, A>,
+ A: Clone
+{
+ f(bx(shift(d, v, a)), bx(shift(d, v, b)))
+}
+
/// Substitute all occurrences of a variable with an expression
///
/// ```c