appendJoinRecord.ps

class SemigroupJoinRecord rl rl2 row row' row''
  | rl -> row, rl2 -> row', rl rl2 -> row''
  where
    appendJoinRecordImpl :: RLProxy rl -> RLProxy rl2 -> Record row -> Record row' -> Record row''

instance appendJoinRecordCons ::
  ( IsSymbol name
  , Semigroup ty
  , RowCons name ty trash row
  , SemigroupJoinRecord tail other' row row' tailRow''
  , RowListRemove name other other'
  , ListToRow other' row'
  , RowLacks name tailRow''
  , RowCons name ty tailRow'' row''
  ) => SemigroupJoinRecord (Cons name ty tail) other row row' row'' where
  appendJoinRecordImpl _ _ a b =
      insert namep valC rest
    where
      namep = SProxy :: SProxy name
      valA = get namep a
      valB = get namep b
      valC = valA <> valB
      tailp = RLProxy :: RLProxy tail
      otherp' = RLProxy :: RLProxy other'
      rest = appendJoinRecordImpl tailp otherp' a b


instance appendJoinRecordANil ::
  SemigroupJoinRecord other Nil row row' row where
  appendJoinRecordImpl _ _ a _ = a
  
instance appendJoinRecordNilB ::
  SemigroupJoinRecord Nil other row row' row' where
  appendJoinRecordImpl _ _ _ b = b

appendJoinRecord :: forall row row' row'' rl rl2
   . RowToList row rl
  => RowToList row' rl2
  => SemigroupJoinRecord rl rl2 row row' row''
  => Record row
  -> Record row'
  -> Record row''
appendJoinRecord a b = appendJoinRecordImpl (RLProxy :: RLProxy rl) (RLProxy :: RLProxy rl2) a b