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optional fields improvements

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This commit is contained in:
Folkert 2020-07-21 15:25:21 +02:00
parent 48aebc5c59
commit b45b39af5e
14 changed files with 329 additions and 47 deletions
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24
compiler/unify/src/unify.rs
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@ -327,13 +327,24 @@ fn unify_shared_fields(
let num_shared_fields = shared_fields.len();
for (name, (actual, expected)) in shared_fields {
let problems = unify_pool(subs, pool, actual.into_inner(), expected.into_inner());
let local_problems = unify_pool(subs, pool, actual.into_inner(), expected.into_inner());
if problems.is_empty() {
if local_problems.is_empty() {
use RecordField::*;
// If either field is Required, both are Required.
// Unification of optional fields
//
// Demanded does not unify with Optional
// Unifying Required with Demanded => Demanded
// Unifying Optional with Required => Required
// Unifying X with X => X
let actual = match (actual, expected) {
(Demanded(_), Optional(_)) | (Optional(_), Demanded(_)) => {
continue;
}
(Demanded(val), Required(_))
| (Required(val), Demanded(_))
| (Demanded(val), Demanded(_)) => Demanded(val),
(Required(val), Required(_)) => Required(val),
(Required(val), Optional(_)) => Required(val),
(Optional(val), Required(_)) => Required(val),
@ -614,13 +625,14 @@ fn unify_shared_tags(
}
}
fn has_no_required_fields<'a, I, T>(fields: &mut I) -> bool
fn has_only_optional_fields<'a, I, T>(fields: &mut I) -> bool
where
I: Iterator<Item = &'a RecordField<T>>,
T: 'a,
{
fields.all(|field| match field {
RecordField::Required(_) => false,
RecordField::Demanded(_) => false,
RecordField::Optional(_) => true,
})
}
@ -638,11 +650,11 @@ fn unify_flat_type(
match (left, right) {
(EmptyRecord, EmptyRecord) => merge(subs, ctx, Structure(left.clone())),
(Record(fields, ext), EmptyRecord) if has_no_required_fields(&mut fields.values()) => {
(Record(fields, ext), EmptyRecord) if has_only_optional_fields(&mut fields.values()) => {
unify_pool(subs, pool, *ext, ctx.second)
}
(EmptyRecord, Record(fields, ext)) if has_no_required_fields(&mut fields.values()) => {
(EmptyRecord, Record(fields, ext)) if has_only_optional_fields(&mut fields.values()) => {
unify_pool(subs, pool, ctx.first, *ext)
}