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Merge pull request #1302 from rtfeldman/constrain_expr2_var
Constrain Expr2::Var
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commit
0ff7c98def
@ -21,7 +21,7 @@ use roc_types::{
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pub enum Constraint<'a> {
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Eq(Type2, Expected<Type2>, Category, Region),
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// Store(Type, Variable, &'static str, u32),
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// Lookup(Symbol, Expected<Type>, Region),
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Lookup(Symbol, Expected<Type2>, Region),
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// Pattern(Region, PatternCategory, Type, PExpected<Type>),
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And(BumpVec<'a, Constraint<'a>>),
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Let(&'a LetConstraint<'a>),
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@ -52,6 +52,7 @@ pub fn constrain_expr<'a>(
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Expr2::SmallStr(_) => Eq(str_type(env.pool), expected, Category::Str, region),
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Expr2::Blank => True,
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Expr2::EmptyRecord => constrain_empty_record(expected, region),
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Expr2::Var(symbol) => Lookup(*symbol, expected, region),
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Expr2::SmallInt { var, .. } => {
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let mut flex_vars = BumpVec::with_capacity_in(1, arena);
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@ -1,7 +1,7 @@
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#![allow(clippy::all)]
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#![allow(dead_code)]
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use crate::lang::constrain::Constraint::{self, *};
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use crate::lang::pool::Pool;
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use crate::lang::pool::{Pool, ShallowClone};
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use crate::lang::types::Type2;
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use bumpalo::Bump;
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use roc_can::expected::{Expected, PExpected};
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@ -270,75 +270,79 @@ fn solve<'a>(
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// }
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// }
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// }
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// Lookup(symbol, expectation, region) => {
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// match env.vars_by_symbol.get(&symbol) {
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// Some(var) => {
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// // Deep copy the vars associated with this symbol before unifying them.
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// // Otherwise, suppose we have this:
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// //
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// // identity = \a -> a
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// //
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// // x = identity 5
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// //
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// // When we call (identity 5), it's important that we not unify
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// // on identity's original vars. If we do, the type of `identity` will be
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// // mutated to be `Int -> Int` instead of `a -> `, which would be incorrect;
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// // the type of `identity` is more general than that!
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// //
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// // Instead, we want to unify on a *copy* of its vars. If the copy unifies
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// // successfully (in this case, to `Int -> Int`), we can use that to
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// // infer the type of this lookup (in this case, `Int`) without ever
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// // having mutated the original.
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// //
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// // If this Lookup is targeting a value in another module,
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// // then we copy from that module's Subs into our own. If the value
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// // is being looked up in this module, then we use our Subs as both
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// // the source and destination.
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// let actual = deep_copy_var(subs, rank, pools, *var);
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// let expected = type_to_var(
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// subs,
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// rank,
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// pools,
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// cached_aliases,
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// expectation.get_type_ref(),
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// );
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// match unify(subs, actual, expected) {
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// Success(vars) => {
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// introduce(subs, rank, pools, &vars);
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//
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// state
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// }
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//
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// Failure(vars, actual_type, expected_type) => {
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// introduce(subs, rank, pools, &vars);
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//
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// let problem = TypeError::BadExpr(
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// *region,
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// Category::Lookup(*symbol),
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// actual_type,
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// expectation.clone().replace(expected_type),
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// );
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//
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// problems.push(problem);
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//
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// state
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// }
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// BadType(vars, problem) => {
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// introduce(subs, rank, pools, &vars);
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//
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// problems.push(TypeError::BadType(problem));
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//
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// state
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// }
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// }
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// }
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// None => {
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// problems.push(TypeError::UnexposedLookup(*symbol));
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//
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// state
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// }
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// }
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// }
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Lookup(symbol, expectation, region) => {
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match env.vars_by_symbol.get(&symbol) {
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Some(var) => {
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// Deep copy the vars associated with this symbol before unifying them.
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// Otherwise, suppose we have this:
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//
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// identity = \a -> a
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//
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// x = identity 5
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//
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// When we call (identity 5), it's important that we not unify
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// on identity's original vars. If we do, the type of `identity` will be
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// mutated to be `Int -> Int` instead of `a -> `, which would be incorrect;
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// the type of `identity` is more general than that!
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//
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// Instead, we want to unify on a *copy* of its vars. If the copy unifies
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// successfully (in this case, to `Int -> Int`), we can use that to
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// infer the type of this lookup (in this case, `Int`) without ever
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// having mutated the original.
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//
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// If this Lookup is targeting a value in another module,
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// then we copy from that module's Subs into our own. If the value
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// is being looked up in this module, then we use our Subs as both
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// the source and destination.
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let actual = deep_copy_var(subs, rank, pools, *var);
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let expected = type_to_var(
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arena,
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mempool,
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subs,
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rank,
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pools,
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cached_aliases,
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expectation.get_type_ref(),
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);
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match unify(subs, actual, expected) {
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Success(vars) => {
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introduce(subs, rank, pools, &vars);
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state
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}
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Failure(vars, actual_type, expected_type) => {
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introduce(subs, rank, pools, &vars);
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let problem = TypeError::BadExpr(
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*region,
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Category::Lookup(*symbol),
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actual_type,
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expectation.shallow_clone().replace(expected_type),
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);
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problems.push(problem);
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state
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}
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BadType(vars, problem) => {
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introduce(subs, rank, pools, &vars);
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problems.push(TypeError::BadType(problem));
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state
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}
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}
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}
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None => {
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problems.push(TypeError::UnexposedLookup(*symbol));
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state
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}
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}
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}
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And(sub_constraints) => {
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let mut state = state;
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