diff options
Diffstat (limited to 'src')
-rw-r--r-- | src/core.rs | 120 |
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 |