mergeParfor ExpA (VarE v) = lookupSubst VarA v ExpA (VarE <$> mergeParfor VarA v)
mergeParfor ExpA (VarE v) = lookupSubst VarA v ExpA (VarE <$> mergeParfor VarA v)
mergeParfor ExpA (VarE v) = lookupSubst VarA v ExpA (VarE <$> mergeParfor VarA v)