diff options
author | FintanH | 2019-07-31 12:05:48 +0100 |
---|---|---|
committer | FintanH | 2019-08-01 00:03:32 +0100 |
commit | a53fc6e6767bba80bf1697d732d88c4a1e0e9e42 (patch) | |
tree | 34fb4f39e4dd90f75c48f1f70065f25b6fadcd56 /dhall/src/phase | |
parent | 2a6a37398394a33e281fa4f2055a3b33c21502c3 (diff) |
Add the typechecking of RecursiveRecordMerge.
This introduces an external function for HashMaps to perform an outer
join so that you can do a unionWith but with more power by having a new
tagert type.
Using outer_join and recursively looking through records of records we
have an implementation for combining records.
Diffstat (limited to 'dhall/src/phase')
-rw-r--r-- | dhall/src/phase/normalize.rs | 53 | ||||
-rw-r--r-- | dhall/src/phase/typecheck.rs | 81 |
2 files changed, 126 insertions, 8 deletions
diff --git a/dhall/src/phase/normalize.rs b/dhall/src/phase/normalize.rs index be2ba51..e3c5d68 100644 --- a/dhall/src/phase/normalize.rs +++ b/dhall/src/phase/normalize.rs @@ -372,6 +372,59 @@ enum Ret<'a> { Expr(ExprF<Thunk, X>), } +/// Performs an outer join of two HashMaps. +/// +/// # Arguments +/// +/// * `ft` - Will convert the values of the first map +/// into the target value. +/// +/// * `fu` - Will convert the values of the second map +/// into the target value. +/// +/// * `ftu` - Will convert the key and values from both maps +/// into the target type. +/// +/// # Description +/// +/// If the key is present in both maps then the final value for +/// that key is computed via the `ftu` function. Otherwise, the +/// final value will be calculated by either the `ft` or `fu` value +/// depending on which map the key is present in. +/// +/// The final map will contain all keys from the two input maps with +/// also values computed as per above. +pub(crate) fn outer_join<K, T, U, V>( + mut ft: impl FnMut(&T) -> V, + mut fu: impl FnMut(&U) -> V, + mut ftu: impl FnMut(&K, &T, &U) -> V, + map1: &HashMap<K, T>, + map2: &HashMap<K, U>, +) -> HashMap<K, V> +where + K: std::hash::Hash + Eq + Clone, +{ + let mut kus = HashMap::new(); + for (k1, t) in map1 { + let v = if let Some(u) = map2.get(k1) { + // The key exists in both maps + // so use all values for computation + ftu(k1, t, u) + } else { + // Key only exists in map1 + ft(t) + }; + kus.insert(k1.clone(), v); + } + + for (k1, u) in map2 { + // Insert if key was missing in map1 + kus.entry(k1.clone()).or_insert(fu(u)); + } + + kus +} + fn merge_maps<K, V>( map1: &HashMap<K, V>, map2: &HashMap<K, V>, diff --git a/dhall/src/phase/typecheck.rs b/dhall/src/phase/typecheck.rs index 419b2e2..7aaee42 100644 --- a/dhall/src/phase/typecheck.rs +++ b/dhall/src/phase/typecheck.rs @@ -598,6 +598,71 @@ fn type_last_layer( } Ok(RetTypeOnly(text_type)) } + BinOp(RecursiveRecordMerge, l, r) => { + // A recursive function to dig down into + // records of records when merging. + fn combine_record_types( + ctx: &TypecheckContext, + kts_l: HashMap<Label, TypeThunk>, + kts_r: HashMap<Label, TypeThunk>, + ) -> Result<Typed, TypeError> { + use crate::phase::normalize::outer_join; + + // If the Label exists for both records and Type for the values + // are records themselves, then we hit the recursive case. + // Otherwise we have a field collision. + let combine = |k: &Label, inner_l: &TypeThunk, inner_r: &TypeThunk| + -> Result<Typed, TypeError> { + match (inner_l.to_value(), inner_r.to_value()) { + (Value::RecordType(inner_l_kvs), Value::RecordType(inner_r_kvs)) => + combine_record_types(ctx, inner_l_kvs, inner_r_kvs), + (_, _) => Err(TypeError::new(ctx, FieldCollision(k.clone()))), + } + }; + + let kts: HashMap<Label, Result<Typed, TypeError>> = outer_join( + |l| Ok(l.to_type()), + |r| Ok(r.to_type()), + |k: &Label, l: &TypeThunk, r: &TypeThunk| combine(k, l, r), + &kts_l, + &kts_r, + ); + + Ok(tck_record_type( + ctx, + kts.into_iter().map(|(x, v)| v.map(|r| (x.clone(), r))) + )? + .into_type()) + }; + + let l_type = l.get_type()?; + let l_kind = l_type.get_type()?; + let r_type = r.get_type()?; + let r_kind = r_type.get_type()?; + + // Check the equality of kinds. + // This is to disallow expression such as: + // "{ x = Text } // { y = 1 }" + ensure_equal!( + l_kind, + r_kind, + mkerr(RecordMismatch(l.clone(), r.clone())), + ); + + // Extract the LHS record type + let kts_x = match l_type.to_value() { + Value::RecordType(kts) => kts, + _ => return Err(mkerr(MustCombineRecord(l.clone()))), + }; + + // Extract the RHS record type + let kts_y = match r_type.to_value() { + Value::RecordType(kts) => kts, + _ => return Err(mkerr(MustCombineRecord(r.clone()))), + }; + + combine_record_types(ctx, kts_x, kts_y).map(|r| RetTypeOnly(r)) + } BinOp(o @ ListAppend, l, r) => { match l.get_type()?.to_value() { Value::AppliedBuiltin(List, _) => {} @@ -1120,14 +1185,14 @@ mod spec_tests { ti_success!(ti_success_unit_RecordTypeNestedKind, "unit/RecordTypeNestedKind"); ti_success!(ti_success_unit_RecordTypeNestedKindLike, "unit/RecordTypeNestedKindLike"); ti_success!(ti_success_unit_RecordTypeType, "unit/RecordTypeType"); - // ti_success!(ti_success_unit_RecursiveRecordMergeLhsEmpty, "unit/RecursiveRecordMergeLhsEmpty"); - // ti_success!(ti_success_unit_RecursiveRecordMergeRecursively, "unit/RecursiveRecordMergeRecursively"); - // ti_success!(ti_success_unit_RecursiveRecordMergeRecursivelyKinds, "unit/RecursiveRecordMergeRecursivelyKinds"); - // ti_success!(ti_success_unit_RecursiveRecordMergeRecursivelyTypes, "unit/RecursiveRecordMergeRecursivelyTypes"); - // ti_success!(ti_success_unit_RecursiveRecordMergeRhsEmpty, "unit/RecursiveRecordMergeRhsEmpty"); - // ti_success!(ti_success_unit_RecursiveRecordMergeTwo, "unit/RecursiveRecordMergeTwo"); - // ti_success!(ti_success_unit_RecursiveRecordMergeTwoKinds, "unit/RecursiveRecordMergeTwoKinds"); - // ti_success!(ti_success_unit_RecursiveRecordMergeTwoTypes, "unit/RecursiveRecordMergeTwoTypes"); + ti_success!(ti_success_unit_RecursiveRecordMergeLhsEmpty, "unit/RecursiveRecordMergeLhsEmpty"); + ti_success!(ti_success_unit_RecursiveRecordMergeRecursively, "unit/RecursiveRecordMergeRecursively"); + ti_success!(ti_success_unit_RecursiveRecordMergeRecursivelyKinds, "unit/RecursiveRecordMergeRecursivelyKinds"); + ti_success!(ti_success_unit_RecursiveRecordMergeRecursivelyTypes, "unit/RecursiveRecordMergeRecursivelyTypes"); + ti_success!(ti_success_unit_RecursiveRecordMergeRhsEmpty, "unit/RecursiveRecordMergeRhsEmpty"); + ti_success!(ti_success_unit_RecursiveRecordMergeTwo, "unit/RecursiveRecordMergeTwo"); + ti_success!(ti_success_unit_RecursiveRecordMergeTwoKinds, "unit/RecursiveRecordMergeTwoKinds"); + ti_success!(ti_success_unit_RecursiveRecordMergeTwoTypes, "unit/RecursiveRecordMergeTwoTypes"); // ti_success!(ti_success_unit_RecursiveRecordTypeMergeRecursively, "unit/RecursiveRecordTypeMergeRecursively"); // ti_success!(ti_success_unit_RecursiveRecordTypeMergeRecursivelyKinds, "unit/RecursiveRecordTypeMergeRecursivelyKinds"); // ti_success!(ti_success_unit_RecursiveRecordTypeMergeRecursivelyTypes, "unit/RecursiveRecordTypeMergeRecursivelyTypes"); |