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Constrain optional record fields

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This commit is contained in:
Richard Feldman 2020-07-18 13:12:04 -04:00
parent 8fc9a450b3
commit 1409421de2
2 changed files with 55 additions and 27 deletions
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69
compiler/constrain/src/pattern.rs
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@ -2,13 +2,13 @@ use crate::builtins;
use roc_can::constraint::Constraint;
use roc_can::expected::{Expected, PExpected};
use roc_can::pattern::Pattern::{self, *};
use roc_can::pattern::RecordDestruct;
use roc_can::pattern::{DestructType, RecordDestruct};
use roc_collections::all::{Index, SendMap};
use roc_module::ident::Lowercase;
use roc_module::symbol::Symbol;
use roc_region::all::{Located, Region};
use roc_types::subs::Variable;
use roc_types::types::{Category, PReason, PatternCategory, Type};
use roc_types::types::{Category, PReason, PatternCategory, RecordField, Type};
pub struct PatternState {
pub headers: SendMap<Symbol, Located<Type>>,
@ -61,12 +61,20 @@ fn headers_from_annotation_help(
RecordDestructure { destructs, .. } => match annotation.value.shallow_dealias() {
Type::Record(fields, _) => {
for destruct in destructs {
// NOTE ignores the .guard field.
if let Some(field_type) = fields.get(&destruct.value.label) {
for loc_destruct in destructs {
let destruct = &loc_destruct.value;
// NOTE: We ignore both Guard and optionality when
// determining the type of the assigned def (which is what
// gets added to the header here).
//
// For example, no matter whether it's `{ x } = rec` or
// `{ x ? 0 } = rec` or `{ x: 5 } -> ...` in all cases
// the type of `x` within the binding itself is the same.
if let Some(field_type) = fields.get(&destruct.label) {
headers.insert(
destruct.value.symbol,
Located::at(annotation.region, field_type.clone()),
destruct.symbol,
Located::at(annotation.region, field_type.clone().into_inner()),
);
} else {
return false;
@ -179,7 +187,7 @@ pub fn constrain_pattern(
state.vars.push(*ext_var);
let ext_type = Type::Variable(*ext_var);
let mut field_types: SendMap<Lowercase, Type> = SendMap::default();
let mut field_types: SendMap<Lowercase, RecordField<Type>> = SendMap::default();
for Located {
value:
@ -187,7 +195,7 @@ pub fn constrain_pattern(
var,
label,
symbol,
guard,
typ,
},
..
} in destructs
@ -201,23 +209,36 @@ pub fn constrain_pattern(
.insert(*symbol, Located::at(region, pat_type.clone()));
}
field_types.insert(label.clone(), pat_type.clone());
let field_type = match typ {
DestructType::Guard(guard_var, loc_guard) => {
state.constraints.push(Constraint::Pattern(
region,
PatternCategory::PatternGuard,
Type::Variable(*guard_var),
PExpected::ForReason(
PReason::PatternGuard,
pat_type.clone(),
loc_guard.region,
),
));
state.vars.push(*guard_var);
if let Some((guard_var, loc_guard)) = guard {
state.constraints.push(Constraint::Pattern(
region,
PatternCategory::PatternGuard,
Type::Variable(*guard_var),
PExpected::ForReason(
PReason::PatternGuard,
pat_type.clone(),
loc_guard.region,
),
));
state.vars.push(*guard_var);
constrain_pattern(&loc_guard.value, loc_guard.region, expected, state);
constrain_pattern(&loc_guard.value, loc_guard.region, expected, state);
}
RecordField::Required(pat_type)
}
DestructType::Optional(_var) => {
todo!("Add a constraint for the default value.");
// RecordField::Optional(pat_type)
}
DestructType::Required => {
// No extra constraints necessary.
RecordField::Required(pat_type)
}
};
field_types.insert(label.clone(), field_type);
state.vars.push(*var);
}