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type inference for pattern guards

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This commit is contained in:
Folkert 2020-03-21 00:39:52 +01:00
parent 655dc32098
commit 920928399a
9 changed files with 230 additions and 57 deletions
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47
compiler/constrain/src/uniq.rs
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@ -4,7 +4,7 @@ use roc_can::constraint::Constraint::{self, *};
use roc_can::constraint::LetConstraint;
use roc_can::def::{Declaration, Def};
use roc_can::expected::{Expected, PExpected};
use roc_can::expr::{Expr, Field};
use roc_can::expr::{Expr, Field, WhenBranch};
use roc_can::pattern::{Pattern, RecordDestruct};
use roc_collections::all::{ImMap, ImSet, SendMap};
use roc_module::ident::{Ident, Lowercase};
@ -1006,15 +1006,14 @@ pub fn constrain_expr(
Expected::FromAnnotation(name, arity, _, typ) => {
constraints.push(Eq(Type::Variable(*expr_var), expected.clone(), region));
for (index, (loc_pattern, loc_expr)) in branches.iter().enumerate() {
for (index, when_branch) in branches.iter().enumerate() {
let branch_con = constrain_when_branch(
var_store,
var_usage,
applied_usage_constraint,
env,
region,
&loc_pattern,
loc_expr,
when_branch,
PExpected::ForReason(
PReason::WhenMatch { index },
cond_type.clone(),
@ -1040,15 +1039,14 @@ pub fn constrain_expr(
let branch_type = Variable(*expr_var);
let mut branch_cons = Vec::with_capacity(branches.len());
for (index, (loc_pattern, loc_expr)) in branches.iter().enumerate() {
for (index, when_branch) in branches.iter().enumerate() {
let branch_con = constrain_when_branch(
var_store,
var_usage,
applied_usage_constraint,
env,
region,
&loc_pattern,
loc_expr,
when_branch,
PExpected::ForReason(
PReason::WhenMatch { index },
cond_type.clone(),
@ -1440,8 +1438,7 @@ fn constrain_when_branch(
applied_usage_constraint: &mut ImSet<Symbol>,
env: &Env,
region: Region,
loc_pattern: &Located<Pattern>,
loc_expr: &Located<Expr>,
when_branch: &WhenBranch,
pattern_expected: PExpected<Type>,
expr_expected: Expected<Type>,
) -> Constraint {
@ -1451,7 +1448,7 @@ fn constrain_when_branch(
var_usage,
applied_usage_constraint,
region,
&loc_expr.value,
&when_branch.value.value,
expr_expected,
);
@ -1461,8 +1458,34 @@ fn constrain_when_branch(
constraints: Vec::with_capacity(1),
};
// mutates the state, so return value is not used
constrain_pattern(var_store, &mut state, &loc_pattern, pattern_expected);
for loc_pattern in &when_branch.patterns {
// mutates the state, so return value is not used
constrain_pattern(
var_store,
&mut state,
&loc_pattern,
pattern_expected.clone(),
);
}
if let Some(loc_guard) = &when_branch.guard {
let guard_uniq_var = var_store.fresh();
state.vars.push(guard_uniq_var);
let bool_type = attr_type(
Bool::variable(guard_uniq_var),
Type::Variable(Variable::BOOL),
);
state.constraints.push(constrain_expr(
env,
var_store,
var_usage,
applied_usage_constraint,
loc_guard.region,
&loc_guard.value,
Expected::ForReason(Reason::WhenGuard, bool_type, loc_guard.region),
));
}
Constraint::Let(Box::new(LetConstraint {
rigid_vars: Vec::new(),